Practice paper 6 — Grade 11 Life Sciences (Easified, CAPS-aligned)
Notes
This paper lives in the app. Answer in sentences: what it is, how it works, and one worked case from the situation to the result. Draw the picture when the question is visual. Do not invent a formula.
150 min · 92 Marks · 28 questions
Learn the paper in the app: notes, a marks breakdown, the formula you need, and the board working. You do not need to download it.
Life Sciences Grade 11. Use this case. A leaf with a white edge. A variegated leaf is left in the dark for two days so stored starch is used up, then put in the light. Iodine later turns the green part blue-black and leaves the white edge brown. The white edge had no chlorophyll, so it made no starch even though it had the same light, the same air and the same leaf stalk. Light alone did not make the starch. Chlorophyll had to be there to catch it. In sentences, say what Photosynthesis is doing here, from the situation to the result.
Photosynthesis
Notes: A foil-and-iodine test on a leaf from the school garden is the worked case.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. A leaf with a white edge. A variegated leaf is left in the dark for two days so stored starch is used up, then put in the light. Iodine later turns the green part blue-black and leaves the white edge brown. The white edge had no chlorophyll, so it made no starch even though it had the same light, the same air and the same leaf stalk. Light alone did not make the starch. Chlorophyll had to be there to catch it. In sentences, say what Photosynthesis is doing here, from the situation to the result.
In other words — as if you have never seen this before
Photosynthesis. It happens in chloroplasts. Chlorophyll absorbs the light. In the light-dependent part, light splits water and oxygen is given off. In the light-independent part, carbon dioxide is built into glucose. The word equation is carbon dioxide + water, with light and chlorophyll, gives glucose + oxygen. A leaf is thin, broad and full of stomata so that light and carbon dioxide can reach the chloroplasts.
2. What do we already know?
A foil-and-iodine test on a leaf from the school garden is the worked case.
3. Which method — and why this one?
Photosynthesis. It happens in chloroplasts. Chlorophyll absorbs the light. In the light-dependent part, light splits water and oxygen is given off. In the light-independent part, carbon dioxide is built into glucose. The word equation is carbon dioxide + water, with light and chlorophyll, gives glucose + oxygen. A leaf is thin, broad and full of stomata so that light and carbon dioxide can reach the chloroplasts.
4. Step-by-step working
01 / 07
What it is
Photosynthesis is how green plants store light energy as glucose, using carbon dioxide and water, and releasing oxygen.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
It happens in chloroplasts. Chlorophyll absorbs the light. In the light-dependent part, light splits water and oxygen is given off. In the light-independent part, carbon dioxide is built into glucose. The word equation is carbon dioxide + water, with light and chlorophyll, gives glucose + oxygen. A leaf is thin, broad and full of stomata so that light and carbon dioxide can reach the chloroplasts.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A spinach leaf in sun on a Pretoria windowsill. Light hits the palisade cells. Water has come up the xylem. Carbon dioxide enters through open stomata. Glucose is made and can be stored as starch. At night the light is gone, so photosynthesis stops, even though the leaf is still alive. The same leaf will still respire at night. Cover the leaf with foil and test later with iodine: the covered part stays brown, the lit part goes blue-black. No light, no new starch.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Copy onto your answer sheet — in this order
Answer: Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say photosynthesis happens in mitochondria, or that plants do not respire.
2 · 4 Marks · Animal nutrition
Life Sciences Grade 11. Use this case. Pap and grilled chicken. The pap is starch. Amylase in the mouth starts it. The chicken is protein. Acid and protease in the stomach start it, and the small intestine finishes it. Fat on the chicken is not touched by the stomach acid. Bile from the liver breaks it into droplets, then lipase splits the droplets. Glucose and amino acids enter the blood at the villi. A classmate who says the stomach absorbs the meal has skipped the villi, which is where the food actually enters the body. In sentences, say what Animal nutrition is doing here, from the situation to the result.
Animal nutrition
Notes: A school lunch is enough of a worked meal: starch, protein and fat on one plate.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Pap and grilled chicken. The pap is starch. Amylase in the mouth starts it. The chicken is protein. Acid and protease in the stomach start it, and the small intestine finishes it. Fat on the chicken is not touched by the stomach acid. Bile from the liver breaks it into droplets, then lipase splits the droplets. Glucose and amino acids enter the blood at the villi. A classmate who says the stomach absorbs the meal has skipped the villi, which is where the food actually enters the body. In sentences, say what Animal nutrition is doing here, from the situation to the result.
In other words — as if you have never seen this before
Animal nutrition. The path is mouth, oesophagus, stomach, small intestine, large intestine, anus. Teeth and saliva start starch digestion. The stomach’s acid and protease start protein. The liver makes bile, which emulsifies fats. The pancreas adds enzymes for starch, protein and fat. The small intestine’s villi give a huge surface for absorption into the blood. The large intestine takes back water. Egestion is not excretion. Excretion removes metabolic waste such as urea.
2. What do we already know?
A school lunch is enough of a worked meal: starch, protein and fat on one plate.
3. Which method — and why this one?
Animal nutrition. The path is mouth, oesophagus, stomach, small intestine, large intestine, anus. Teeth and saliva start starch digestion. The stomach’s acid and protease start protein. The liver makes bile, which emulsifies fats. The pancreas adds enzymes for starch, protein and fat. The small intestine’s villi give a huge surface for absorption into the blood. The large intestine takes back water. Egestion is not excretion. Excretion removes metabolic waste such as urea.
4. Step-by-step working
01 / 07
What it is
Animal nutrition is how a human takes food in, breaks it down, absorbs the useful molecules, and egests what cannot be used.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
The path is mouth, oesophagus, stomach, small intestine, large intestine, anus. Teeth and saliva start starch digestion. The stomach’s acid and protease start protein. The liver makes bile, which emulsifies fats. The pancreas adds enzymes for starch, protein and fat. The small intestine’s villi give a huge surface for absorption into the blood. The large intestine takes back water. Egestion is not excretion. Excretion removes metabolic waste such as urea.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A cheese sandwich. Starch in the bread meets amylase in the mouth. Protein in the cheese is attacked in the stomach and finished in the small intestine. Fat in the cheese is emulsified by bile, then lipase splits it. Glucose and amino acids cross the villi into the blood. Fatty products enter the lymph. Fibre continues and is egested. If the villi were flattened, as in untreated coeliac disease, the food could be digested and still not absorbed. Digestion and absorption are two different events.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Copy onto your answer sheet — in this order
Answer: Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say bile digests fat the way lipase does, or that the stomach absorbs most of the food.
3 · 4 Marks · Cellular respiration
Life Sciences Grade 11. Use this case. Thirty-eight and two. A learner sitting and reading is using aerobic respiration. Glucose is broken down fully, in the mitochondria, and the school table gives that yield as about 38 ATP. The same learner in a hard sprint cannot supply oxygen fast enough. Muscles then use anaerobic respiration and the table gives 2 ATP, plus lactic acid. The glucose was available both times. The oxygen, and the mitochondria’s full path, were not. Yeast’s anaerobic product is ethanol. The runner’s is lactic acid. The small yield is the shared point. In sentences, say what Cellular respiration is doing here, from the situation to the result.
Cellular respiration
Notes: The burn in a 100 m on sports day, then the heavy breathing after, is anaerobic then aerobic.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Thirty-eight and two. A learner sitting and reading is using aerobic respiration. Glucose is broken down fully, in the mitochondria, and the school table gives that yield as about 38 ATP. The same learner in a hard sprint cannot supply oxygen fast enough. Muscles then use anaerobic respiration and the table gives 2 ATP, plus lactic acid. The glucose was available both times. The oxygen, and the mitochondria’s full path, were not. Yeast’s anaerobic product is ethanol. The runner’s is lactic acid. The small yield is the shared point. In sentences, say what Cellular respiration is doing here, from the situation to the result.
In other words — as if you have never seen this before
Cellular respiration. Aerobic respiration needs oxygen and happens mostly in mitochondria: glucose + oxygen gives carbon dioxide + water + a usable packet of energy, ATP. Anaerobic respiration in human muscle has no oxygen and ends in lactic acid, with far less ATP. Yeast’s anaerobic path makes ethanol and carbon dioxide. Breathing only brings the oxygen in and the carbon dioxide out. The energy release is inside the cell.
2. What do we already know?
The burn in a 100 m on sports day, then the heavy breathing after, is anaerobic then aerobic.
3. Which method — and why this one?
Cellular respiration. Aerobic respiration needs oxygen and happens mostly in mitochondria: glucose + oxygen gives carbon dioxide + water + a usable packet of energy, ATP. Anaerobic respiration in human muscle has no oxygen and ends in lactic acid, with far less ATP. Yeast’s anaerobic path makes ethanol and carbon dioxide. Breathing only brings the oxygen in and the carbon dioxide out. The energy release is inside the cell.
4. Step-by-step working
01 / 07
What it is
Cellular respiration is how cells release energy from glucose. It is not the same thing as breathing.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
Aerobic respiration needs oxygen and happens mostly in mitochondria: glucose + oxygen gives carbon dioxide + water + a usable packet of energy, ATP. Anaerobic respiration in human muscle has no oxygen and ends in lactic acid, with far less ATP. Yeast’s anaerobic path makes ethanol and carbon dioxide. Breathing only brings the oxygen in and the carbon dioxide out. The energy release is inside the cell.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A learner sprints, then walks. During the sprint the muscle mitochondria cannot get oxygen fast enough, so some glucose is broken down anaerobically and lactic acid builds. That is the burn. In the walk, oxygen catches up and the lactic acid is dealt with. The same learner’s cells were already doing aerobic respiration before the sprint. Plants do this too, in their mitochondria, including at night when they cannot photosynthesise. A breathing rate going up is the supply line, not the reaction itself.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Copy onto your answer sheet — in this order
Answer: Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to write photosynthesis in reverse and call that the whole of respiration, or to place respiration in chloroplasts.
4 · 4 Marks · Gaseous exchange
Life Sciences Grade 11. Use this case. Johannesburg and the coast. At sea level the air pressing into the alveoli is denser, so the oxygen gradient into the blood is steep. On the Highveld, about 1 700 m up, each breath brings less oxygen. Diffusion still happens, but the gradient is shallower, which is why a visitor from Durban is breathless on a flight of stairs in Johannesburg for a few days. The alveoli did not change. The air did. Fluid in those alveoli, as in pneumonia, flattens the gradient even at the coast, because the surface is no longer thin. In sentences, say what Gaseous exchange is doing here, from the situation to the result.
Gaseous exchange
Notes: A peak-flow test at a clinic is about ventilation. The exchange itself is the alveolus you draw in Life Sciences.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Johannesburg and the coast. At sea level the air pressing into the alveoli is denser, so the oxygen gradient into the blood is steep. On the Highveld, about 1 700 m up, each breath brings less oxygen. Diffusion still happens, but the gradient is shallower, which is why a visitor from Durban is breathless on a flight of stairs in Johannesburg for a few days. The alveoli did not change. The air did. Fluid in those alveoli, as in pneumonia, flattens the gradient even at the coast, because the surface is no longer thin. In sentences, say what Gaseous exchange is doing here, from the situation to the result.
In other words — as if you have never seen this before
Gaseous exchange. In humans that surface is the alveoli in the lungs. Each alveolus is one cell thick, wrapped in capillaries. Inhaled air is high in oxygen, so oxygen diffuses into the blood. Blood arriving from the body is high in carbon dioxide, so carbon dioxide diffuses into the air to be exhaled. Breathing moves the air. Gaseous exchange is the diffusion. The tubes of the lung do not do the exchange. The alveoli do.
2. What do we already know?
A peak-flow test at a clinic is about ventilation. The exchange itself is the alveolus you draw in Life Sciences.
3. Which method — and why this one?
Gaseous exchange. In humans that surface is the alveoli in the lungs. Each alveolus is one cell thick, wrapped in capillaries. Inhaled air is high in oxygen, so oxygen diffuses into the blood. Blood arriving from the body is high in carbon dioxide, so carbon dioxide diffuses into the air to be exhaled. Breathing moves the air. Gaseous exchange is the diffusion. The tubes of the lung do not do the exchange. The alveoli do.
4. Step-by-step working
01 / 07
What it is
Gaseous exchange is the diffusion of oxygen into the blood and carbon dioxide out of it, across a thin, moist, large surface.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
In humans that surface is the alveoli in the lungs. Each alveolus is one cell thick, wrapped in capillaries. Inhaled air is high in oxygen, so oxygen diffuses into the blood. Blood arriving from the body is high in carbon dioxide, so carbon dioxide diffuses into the air to be exhaled. Breathing moves the air. Gaseous exchange is the diffusion. The tubes of the lung do not do the exchange. The alveoli do.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. Air enters, the chest expands, alveoli fill. Oxygen crosses into a red blood cell and is carried away. Carbon dioxide crosses out. If the alveoli fill with fluid, or if smoke destroys their walls so the surface shrinks, diffusion fails even though the person is still trying to breathe. A fish uses gills for the same idea: thin, moist, large surface, close to blood. The organ changes. The principle does not. Holding your breath stops the fresh supply. It does not stop the cells needing oxygen.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Copy onto your answer sheet — in this order
Answer: Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say oxygen is pumped into the blood by the lungs, rather than diffusing, or to call breathing the same process as cellular respiration.
5 · 4 Marks · Excretion in humans
Life Sciences Grade 11. Use this case. A dialysis morning. When the nephrons have failed, a machine three times a week does the job of filtration: wastes cross into a fluid the body does not keep. The person’s own kidneys do not regrow between sessions. Skip a week and urea rises. Dialysis is a replacement, not a cure, and it does not put glucose back the way a healthy tubule does. A learner who says the machine is a new kidney has skipped what it cannot do. In sentences, say what Excretion in humans is doing here, from the situation to the result.
Excretion in humans
Notes: Dark urine after a hot taxi-rank afternoon, pale urine after drinking, is ADH in ordinary life.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. A dialysis morning. When the nephrons have failed, a machine three times a week does the job of filtration: wastes cross into a fluid the body does not keep. The person’s own kidneys do not regrow between sessions. Skip a week and urea rises. Dialysis is a replacement, not a cure, and it does not put glucose back the way a healthy tubule does. A learner who says the machine is a new kidney has skipped what it cannot do. In sentences, say what Excretion in humans is doing here, from the situation to the result.
In other words — as if you have never seen this before
Excretion in humans. Blood reaches the nephron under pressure. At the glomerulus, water, urea, glucose and salts are filtered. Large proteins and blood cells stay in the blood. Along the tubule, all the glucose and the salts and water the body still needs are reabsorbed. Urea stays in the fluid and becomes urine. ADH, from the pituitary, makes the collecting duct keep more water when the blood is too concentrated. Sweat and exhaled carbon dioxide are also excretion. Faeces are not. Faeces were never inside the body’s cells as metabolic waste.
2. What do we already know?
Dark urine after a hot taxi-rank afternoon, pale urine after drinking, is ADH in ordinary life.
3. Which method — and why this one?
Excretion in humans. Blood reaches the nephron under pressure. At the glomerulus, water, urea, glucose and salts are filtered. Large proteins and blood cells stay in the blood. Along the tubule, all the glucose and the salts and water the body still needs are reabsorbed. Urea stays in the fluid and becomes urine. ADH, from the pituitary, makes the collecting duct keep more water when the blood is too concentrated. Sweat and exhaled carbon dioxide are also excretion. Faeces are not. Faeces were never inside the body’s cells as metabolic waste.
4. Step-by-step working
01 / 07
What it is
Excretion is the removal of metabolic waste. In humans the kidney is the organ that clears urea and balances water and salts.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
Blood reaches the nephron under pressure. At the glomerulus, water, urea, glucose and salts are filtered. Large proteins and blood cells stay in the blood. Along the tubule, all the glucose and the salts and water the body still needs are reabsorbed. Urea stays in the fluid and becomes urine. ADH, from the pituitary, makes the collecting duct keep more water when the blood is too concentrated. Sweat and exhaled carbon dioxide are also excretion. Faeces are not. Faeces were never inside the body’s cells as metabolic waste.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A learner who has played in the sun and not drunk. Blood is too concentrated. ADH rises. The collecting ducts reabsorb more water. Urine comes out small in volume and dark. After a litre of water, ADH falls, less water is reabsorbed, and urine is pale and plentiful. Glucose in the urine is not normal. It means the tubule could not reabsorb all of it, which is a sign to test for, not a usual step of the nephron. The kidney did not “make” urea. The liver made urea from excess amino acids. The kidney only removed it.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Copy onto your answer sheet — in this order
Answer: The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say the glomerulus chooses useful molecules, or that the kidney produces urea.
6 · 8 Marks · Population ecology
Life Sciences Grade 11. Use this case. A 20 hectare camp. A camp of 20 hectares of decent veld carries 15 cattle through a normal year. The herd grows to 40 because calves were not sold. By August the grass is gone, the cattle lose weight, and three die. The carrying capacity was 15, not 40. Rain the next year does not immediately restore it, because the roots were grazed out. A predator was never involved. Food was the limit. In sentences, say what Population ecology is doing here, from the situation to the result.
Population ecology
Notes: Quelea on grain, or goats on an overstocked village veld, is carrying capacity you can see.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. A 20 hectare camp. A camp of 20 hectares of decent veld carries 15 cattle through a normal year. The herd grows to 40 because calves were not sold. By August the grass is gone, the cattle lose weight, and three die. The carrying capacity was 15, not 40. Rain the next year does not immediately restore it, because the roots were grazed out. A predator was never involved. Food was the limit. In sentences, say what Population ecology is doing here, from the situation to the result.
In other words — as if you have never seen this before
Population ecology. Population size is how many. Density is how many in a given area. Growth often starts slow, becomes fast, then levels off at the carrying capacity, the number the place can support. Limiting factors include food, water, space, disease and predators. Predator and prey numbers rise and fall out of step: more prey, then more predators, then fewer prey, then fewer predators.
2. What do we already know?
Quelea on grain, or goats on an overstocked village veld, is carrying capacity you can see.
3. Which method — and why this one?
Population ecology. Population size is how many. Density is how many in a given area. Growth often starts slow, becomes fast, then levels off at the carrying capacity, the number the place can support. Limiting factors include food, water, space, disease and predators. Predator and prey numbers rise and fall out of step: more prey, then more predators, then fewer prey, then fewer predators.
4. Step-by-step working
01 / 07
What it is
Population ecology is how a group of one species changes in number, and what stops it growing forever.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
Population size is how many. Density is how many in a given area. Growth often starts slow, becomes fast, then levels off at the carrying capacity, the number the place can support. Limiting factors include food, water, space, disease and predators. Predator and prey numbers rise and fall out of step: more prey, then more predators, then fewer prey, then fewer predators.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. Quelea birds on a grain field. One season the grain is rich, so the flock grows quickly. The field cannot feed an endless flock. When grain runs out, deaths and departures rise and the flock stops growing. That levelling is carrying capacity, not a decision by the birds to be tidy. If a predator increases after the flock peaks, the prey curve falls next. A drought is a limiting factor even if no predator is involved. Counting birds in sample plots and scaling up is an estimate, not a photograph of every bird.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Copy onto your answer sheet — in this order
Answer: Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to think a population can grow exponentially forever in a real field, or to call all the species in the field one population.
7 · 4 Marks · Human impact on the environment
Life Sciences Grade 11. Use this case. Water hyacinth on the Vaal. Water hyacinth, brought in as an ornamental, covers a stretch of slow water. Light cannot reach the plants underneath. They die, bacteria use up the oxygen, and fish turn up dead. The hyacinth is not pollution from a pipe. It is a living thing in the wrong place, growing faster than anything that eats it here. Pulling one basket out does not finish the job if the fragments grow again. The impact is the lost oxygen, not the colour of the flowers. In sentences, say what Human impact on the environment is doing here, from the situation to the result.
Human impact on the environment
Notes: Wattles in a catchment, and a fish kill below a sewage leak, are the South African cases.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Water hyacinth on the Vaal. Water hyacinth, brought in as an ornamental, covers a stretch of slow water. Light cannot reach the plants underneath. They die, bacteria use up the oxygen, and fish turn up dead. The hyacinth is not pollution from a pipe. It is a living thing in the wrong place, growing faster than anything that eats it here. Pulling one basket out does not finish the job if the fragments grow again. The impact is the lost oxygen, not the colour of the flowers. In sentences, say what Human impact on the environment is doing here, from the situation to the result.
In other words — as if you have never seen this before
Human impact on the environment. The natural greenhouse effect keeps Earth warm enough for life. Burning fossil fuels and cutting forests add extra carbon dioxide, so more heat is trapped. That is the enhanced greenhouse effect. Alien plants outcompete local ones and drink scarce water. Sewage and fertiliser in a river feed algae, which then die and the decay uses up oxygen. Carbon footprint is the greenhouse gas a person or a process is responsible for. Conservation is not only “being nice”. It is keeping the processes, such as clean water and pollination, that people also need.
2. What do we already know?
Wattles in a catchment, and a fish kill below a sewage leak, are the South African cases.
3. Which method — and why this one?
Human impact on the environment. The natural greenhouse effect keeps Earth warm enough for life. Burning fossil fuels and cutting forests add extra carbon dioxide, so more heat is trapped. That is the enhanced greenhouse effect. Alien plants outcompete local ones and drink scarce water. Sewage and fertiliser in a river feed algae, which then die and the decay uses up oxygen. Carbon footprint is the greenhouse gas a person or a process is responsible for. Conservation is not only “being nice”. It is keeping the processes, such as clean water and pollination, that people also need.
4. Step-by-step working
01 / 07
What it is
Human impact is the set of ways people change air, water, soil and other species, and what can still be done about it.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
The natural greenhouse effect keeps Earth warm enough for life. Burning fossil fuels and cutting forests add extra carbon dioxide, so more heat is trapped. That is the enhanced greenhouse effect. Alien plants outcompete local ones and drink scarce water. Sewage and fertiliser in a river feed algae, which then die and the decay uses up oxygen. Carbon footprint is the greenhouse gas a person or a process is responsible for. Conservation is not only “being nice”. It is keeping the processes, such as clean water and pollination, that people also need.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A river below an informal settlement and a ploughed field. Pit latrines and fertiliser both add nutrients. Algae bloom. When they rot, oxygen falls and fish die. Upstream of the settlement the same river still holds fish. The difference is the input, not a change in the definition of a river. On the bank, invasive wattle shades out grassland and uses deep water. Clearing the wattle is a human impact in the other direction. Switching a school’s lights off does not fix a river, but it is the same idea at the scale of a carbon footprint: less waste, less damage.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Copy onto your answer sheet — in this order
Answer: Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to treat the greenhouse effect itself as pollution, or to call a local indigenous tree an alien invader.
8 · 4 Marks · Photosynthesis
Life Sciences Grade 11. Use this case. Pondweed bubbles. A sprig of pondweed under a funnel in bright light gives off a stream of bubbles, about 30 in five minutes. Move the lamp away and the count falls to about 8. Switch the lamp off and the count falls to almost none. The gas that relights a glowing splint is oxygen. The same sprig in the dark is still alive. It has just stopped photosynthesising. Add a pinch of bicarbonate, which supplies carbon dioxide, and the bubble count in the light rises again. In sentences, say what Photosynthesis is doing here, from the situation to the result.
Photosynthesis
Notes: A foil-and-iodine test on a leaf from the school garden is the worked case.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Pondweed bubbles. A sprig of pondweed under a funnel in bright light gives off a stream of bubbles, about 30 in five minutes. Move the lamp away and the count falls to about 8. Switch the lamp off and the count falls to almost none. The gas that relights a glowing splint is oxygen. The same sprig in the dark is still alive. It has just stopped photosynthesising. Add a pinch of bicarbonate, which supplies carbon dioxide, and the bubble count in the light rises again. In sentences, say what Photosynthesis is doing here, from the situation to the result.
In other words — as if you have never seen this before
Photosynthesis. It happens in chloroplasts. Chlorophyll absorbs the light. In the light-dependent part, light splits water and oxygen is given off. In the light-independent part, carbon dioxide is built into glucose. The word equation is carbon dioxide + water, with light and chlorophyll, gives glucose + oxygen. A leaf is thin, broad and full of stomata so that light and carbon dioxide can reach the chloroplasts.
2. What do we already know?
A foil-and-iodine test on a leaf from the school garden is the worked case.
3. Which method — and why this one?
Photosynthesis. It happens in chloroplasts. Chlorophyll absorbs the light. In the light-dependent part, light splits water and oxygen is given off. In the light-independent part, carbon dioxide is built into glucose. The word equation is carbon dioxide + water, with light and chlorophyll, gives glucose + oxygen. A leaf is thin, broad and full of stomata so that light and carbon dioxide can reach the chloroplasts.
4. Step-by-step working
01 / 07
What it is
Photosynthesis is how green plants store light energy as glucose, using carbon dioxide and water, and releasing oxygen.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
It happens in chloroplasts. Chlorophyll absorbs the light. In the light-dependent part, light splits water and oxygen is given off. In the light-independent part, carbon dioxide is built into glucose. The word equation is carbon dioxide + water, with light and chlorophyll, gives glucose + oxygen. A leaf is thin, broad and full of stomata so that light and carbon dioxide can reach the chloroplasts.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A spinach leaf in sun on a Pretoria windowsill. Light hits the palisade cells. Water has come up the xylem. Carbon dioxide enters through open stomata. Glucose is made and can be stored as starch. At night the light is gone, so photosynthesis stops, even though the leaf is still alive. The same leaf will still respire at night. Cover the leaf with foil and test later with iodine: the covered part stays brown, the lit part goes blue-black. No light, no new starch.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Copy onto your answer sheet — in this order
Answer: Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say photosynthesis happens in mitochondria, or that plants do not respire.
9 · 4 Marks · Animal nutrition
Life Sciences Grade 11. Use this case. A blocked bile duct. Bile, made in the liver and stored in the gall bladder, breaks fats into droplets. If the duct is blocked, fat in the meal is not emulsified. The stool becomes pale and fatty, and the fat-soluble vitamins are poorly absorbed. The stomach acid still worked. The protease still worked. The missing step was bile. A learner who treats every digestive problem as “the stomach” has skipped the organ that actually failed. In sentences, say what Animal nutrition is doing here, from the situation to the result.
Animal nutrition
Notes: A school lunch is enough of a worked meal: starch, protein and fat on one plate.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. A blocked bile duct. Bile, made in the liver and stored in the gall bladder, breaks fats into droplets. If the duct is blocked, fat in the meal is not emulsified. The stool becomes pale and fatty, and the fat-soluble vitamins are poorly absorbed. The stomach acid still worked. The protease still worked. The missing step was bile. A learner who treats every digestive problem as “the stomach” has skipped the organ that actually failed. In sentences, say what Animal nutrition is doing here, from the situation to the result.
In other words — as if you have never seen this before
Animal nutrition. The path is mouth, oesophagus, stomach, small intestine, large intestine, anus. Teeth and saliva start starch digestion. The stomach’s acid and protease start protein. The liver makes bile, which emulsifies fats. The pancreas adds enzymes for starch, protein and fat. The small intestine’s villi give a huge surface for absorption into the blood. The large intestine takes back water. Egestion is not excretion. Excretion removes metabolic waste such as urea.
2. What do we already know?
A school lunch is enough of a worked meal: starch, protein and fat on one plate.
3. Which method — and why this one?
Animal nutrition. The path is mouth, oesophagus, stomach, small intestine, large intestine, anus. Teeth and saliva start starch digestion. The stomach’s acid and protease start protein. The liver makes bile, which emulsifies fats. The pancreas adds enzymes for starch, protein and fat. The small intestine’s villi give a huge surface for absorption into the blood. The large intestine takes back water. Egestion is not excretion. Excretion removes metabolic waste such as urea.
4. Step-by-step working
01 / 07
What it is
Animal nutrition is how a human takes food in, breaks it down, absorbs the useful molecules, and egests what cannot be used.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
The path is mouth, oesophagus, stomach, small intestine, large intestine, anus. Teeth and saliva start starch digestion. The stomach’s acid and protease start protein. The liver makes bile, which emulsifies fats. The pancreas adds enzymes for starch, protein and fat. The small intestine’s villi give a huge surface for absorption into the blood. The large intestine takes back water. Egestion is not excretion. Excretion removes metabolic waste such as urea.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A cheese sandwich. Starch in the bread meets amylase in the mouth. Protein in the cheese is attacked in the stomach and finished in the small intestine. Fat in the cheese is emulsified by bile, then lipase splits it. Glucose and amino acids cross the villi into the blood. Fatty products enter the lymph. Fibre continues and is egested. If the villi were flattened, as in untreated coeliac disease, the food could be digested and still not absorbed. Digestion and absorption are two different events.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Copy onto your answer sheet — in this order
Answer: Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say bile digests fat the way lipase does, or that the stomach absorbs most of the food.
10 · 4 Marks · Cellular respiration
Life Sciences Grade 11. Use this case. Bread dough and a 100 m. Yeast in dough has little oxygen. It breaks glucose into ethanol and carbon dioxide, and the dough rises from the gas. That is anaerobic, and it pays the yeast very little ATP. A learner in a 100 m race does the human version: muscles make lactic acid, not ethanol, and the ATP is still a fraction of the aerobic yield. Ten minutes later, with oxygen, the same muscles are back to aerobic respiration in the mitochondria. The dough never grows mitochondria for that. The runner already had them. In sentences, say what Cellular respiration is doing here, from the situation to the result.
Cellular respiration
Notes: The burn in a 100 m on sports day, then the heavy breathing after, is anaerobic then aerobic.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Bread dough and a 100 m. Yeast in dough has little oxygen. It breaks glucose into ethanol and carbon dioxide, and the dough rises from the gas. That is anaerobic, and it pays the yeast very little ATP. A learner in a 100 m race does the human version: muscles make lactic acid, not ethanol, and the ATP is still a fraction of the aerobic yield. Ten minutes later, with oxygen, the same muscles are back to aerobic respiration in the mitochondria. The dough never grows mitochondria for that. The runner already had them. In sentences, say what Cellular respiration is doing here, from the situation to the result.
In other words — as if you have never seen this before
Cellular respiration. Aerobic respiration needs oxygen and happens mostly in mitochondria: glucose + oxygen gives carbon dioxide + water + a usable packet of energy, ATP. Anaerobic respiration in human muscle has no oxygen and ends in lactic acid, with far less ATP. Yeast’s anaerobic path makes ethanol and carbon dioxide. Breathing only brings the oxygen in and the carbon dioxide out. The energy release is inside the cell.
2. What do we already know?
The burn in a 100 m on sports day, then the heavy breathing after, is anaerobic then aerobic.
3. Which method — and why this one?
Cellular respiration. Aerobic respiration needs oxygen and happens mostly in mitochondria: glucose + oxygen gives carbon dioxide + water + a usable packet of energy, ATP. Anaerobic respiration in human muscle has no oxygen and ends in lactic acid, with far less ATP. Yeast’s anaerobic path makes ethanol and carbon dioxide. Breathing only brings the oxygen in and the carbon dioxide out. The energy release is inside the cell.
4. Step-by-step working
01 / 07
What it is
Cellular respiration is how cells release energy from glucose. It is not the same thing as breathing.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
Aerobic respiration needs oxygen and happens mostly in mitochondria: glucose + oxygen gives carbon dioxide + water + a usable packet of energy, ATP. Anaerobic respiration in human muscle has no oxygen and ends in lactic acid, with far less ATP. Yeast’s anaerobic path makes ethanol and carbon dioxide. Breathing only brings the oxygen in and the carbon dioxide out. The energy release is inside the cell.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A learner sprints, then walks. During the sprint the muscle mitochondria cannot get oxygen fast enough, so some glucose is broken down anaerobically and lactic acid builds. That is the burn. In the walk, oxygen catches up and the lactic acid is dealt with. The same learner’s cells were already doing aerobic respiration before the sprint. Plants do this too, in their mitochondria, including at night when they cannot photosynthesise. A breathing rate going up is the supply line, not the reaction itself.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Copy onto your answer sheet — in this order
Answer: Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to write photosynthesis in reverse and call that the whole of respiration, or to place respiration in chloroplasts.
11 · 4 Marks · Gaseous exchange
Life Sciences Grade 11. Use this case. Fewer air sacs. Healthy lungs have an enormous alveolar surface, thin and wet, so oxygen crosses quickly. Smoking destroys walls between alveoli, so many small sacs become fewer large ones. The surface shrinks. The person is breathless on a flight of stairs even at sea level, because less oxygen crosses each breath. The air outside did not change. The surface inside did. An inhaler that opens the bronchi does not rebuild those walls. In sentences, say what Gaseous exchange is doing here, from the situation to the result.
Gaseous exchange
Notes: A peak-flow test at a clinic is about ventilation. The exchange itself is the alveolus you draw in Life Sciences.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Fewer air sacs. Healthy lungs have an enormous alveolar surface, thin and wet, so oxygen crosses quickly. Smoking destroys walls between alveoli, so many small sacs become fewer large ones. The surface shrinks. The person is breathless on a flight of stairs even at sea level, because less oxygen crosses each breath. The air outside did not change. The surface inside did. An inhaler that opens the bronchi does not rebuild those walls. In sentences, say what Gaseous exchange is doing here, from the situation to the result.
In other words — as if you have never seen this before
Gaseous exchange. In humans that surface is the alveoli in the lungs. Each alveolus is one cell thick, wrapped in capillaries. Inhaled air is high in oxygen, so oxygen diffuses into the blood. Blood arriving from the body is high in carbon dioxide, so carbon dioxide diffuses into the air to be exhaled. Breathing moves the air. Gaseous exchange is the diffusion. The tubes of the lung do not do the exchange. The alveoli do.
2. What do we already know?
A peak-flow test at a clinic is about ventilation. The exchange itself is the alveolus you draw in Life Sciences.
3. Which method — and why this one?
Gaseous exchange. In humans that surface is the alveoli in the lungs. Each alveolus is one cell thick, wrapped in capillaries. Inhaled air is high in oxygen, so oxygen diffuses into the blood. Blood arriving from the body is high in carbon dioxide, so carbon dioxide diffuses into the air to be exhaled. Breathing moves the air. Gaseous exchange is the diffusion. The tubes of the lung do not do the exchange. The alveoli do.
4. Step-by-step working
01 / 07
What it is
Gaseous exchange is the diffusion of oxygen into the blood and carbon dioxide out of it, across a thin, moist, large surface.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
In humans that surface is the alveoli in the lungs. Each alveolus is one cell thick, wrapped in capillaries. Inhaled air is high in oxygen, so oxygen diffuses into the blood. Blood arriving from the body is high in carbon dioxide, so carbon dioxide diffuses into the air to be exhaled. Breathing moves the air. Gaseous exchange is the diffusion. The tubes of the lung do not do the exchange. The alveoli do.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. Air enters, the chest expands, alveoli fill. Oxygen crosses into a red blood cell and is carried away. Carbon dioxide crosses out. If the alveoli fill with fluid, or if smoke destroys their walls so the surface shrinks, diffusion fails even though the person is still trying to breathe. A fish uses gills for the same idea: thin, moist, large surface, close to blood. The organ changes. The principle does not. Holding your breath stops the fresh supply. It does not stop the cells needing oxygen.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Copy onto your answer sheet — in this order
Answer: Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say oxygen is pumped into the blood by the lungs, rather than diffusing, or to call breathing the same process as cellular respiration.
12 · 8 Marks · Excretion in humans
Life Sciences Grade 11. Use this case. Two litres of water, then a match. After two litres of water, ADH falls. The collecting ducts let water go. In the next hour the urine is pale and there is a lot of it. The same person, after a football match with no drink, has high ADH. The collecting ducts keep water. Urine is a small dark volume. Glucose in that urine would be a third case: the filter let it through, as it always does, and the tubule failed to take it all back. Healthy nephrons return all the glucose. In sentences, say what Excretion in humans is doing here, from the situation to the result.
Excretion in humans
Notes: Dark urine after a hot taxi-rank afternoon, pale urine after drinking, is ADH in ordinary life.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Two litres of water, then a match. After two litres of water, ADH falls. The collecting ducts let water go. In the next hour the urine is pale and there is a lot of it. The same person, after a football match with no drink, has high ADH. The collecting ducts keep water. Urine is a small dark volume. Glucose in that urine would be a third case: the filter let it through, as it always does, and the tubule failed to take it all back. Healthy nephrons return all the glucose. In sentences, say what Excretion in humans is doing here, from the situation to the result.
In other words — as if you have never seen this before
Excretion in humans. Blood reaches the nephron under pressure. At the glomerulus, water, urea, glucose and salts are filtered. Large proteins and blood cells stay in the blood. Along the tubule, all the glucose and the salts and water the body still needs are reabsorbed. Urea stays in the fluid and becomes urine. ADH, from the pituitary, makes the collecting duct keep more water when the blood is too concentrated. Sweat and exhaled carbon dioxide are also excretion. Faeces are not. Faeces were never inside the body’s cells as metabolic waste.
2. What do we already know?
Dark urine after a hot taxi-rank afternoon, pale urine after drinking, is ADH in ordinary life.
3. Which method — and why this one?
Excretion in humans. Blood reaches the nephron under pressure. At the glomerulus, water, urea, glucose and salts are filtered. Large proteins and blood cells stay in the blood. Along the tubule, all the glucose and the salts and water the body still needs are reabsorbed. Urea stays in the fluid and becomes urine. ADH, from the pituitary, makes the collecting duct keep more water when the blood is too concentrated. Sweat and exhaled carbon dioxide are also excretion. Faeces are not. Faeces were never inside the body’s cells as metabolic waste.
4. Step-by-step working
01 / 07
What it is
Excretion is the removal of metabolic waste. In humans the kidney is the organ that clears urea and balances water and salts.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
Blood reaches the nephron under pressure. At the glomerulus, water, urea, glucose and salts are filtered. Large proteins and blood cells stay in the blood. Along the tubule, all the glucose and the salts and water the body still needs are reabsorbed. Urea stays in the fluid and becomes urine. ADH, from the pituitary, makes the collecting duct keep more water when the blood is too concentrated. Sweat and exhaled carbon dioxide are also excretion. Faeces are not. Faeces were never inside the body’s cells as metabolic waste.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A learner who has played in the sun and not drunk. Blood is too concentrated. ADH rises. The collecting ducts reabsorb more water. Urine comes out small in volume and dark. After a litre of water, ADH falls, less water is reabsorbed, and urine is pale and plentiful. Glucose in the urine is not normal. It means the tubule could not reabsorb all of it, which is a sign to test for, not a usual step of the nephron. The kidney did not “make” urea. The liver made urea from excess amino acids. The kidney only removed it.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Copy onto your answer sheet — in this order
Answer: The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to say the glomerulus chooses useful molecules, or that the kidney produces urea.
13 · 4 Marks · Population ecology
Life Sciences Grade 11. Use this case. Ducks on a park pond. A few ducks on a new pond breed, and for a while the number climbs fast. Then nesting sites and food run out. The number levels off. That level is the carrying capacity of this pond, not of ducks in general. Add bread from visitors and the level can rise for a season, then fall when the bread stops. A predator is not required. The pond’s own limits are enough. In sentences, say what Population ecology is doing here, from the situation to the result.
Population ecology
Notes: Quelea on grain, or goats on an overstocked village veld, is carrying capacity you can see.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Ducks on a park pond. A few ducks on a new pond breed, and for a while the number climbs fast. Then nesting sites and food run out. The number levels off. That level is the carrying capacity of this pond, not of ducks in general. Add bread from visitors and the level can rise for a season, then fall when the bread stops. A predator is not required. The pond’s own limits are enough. In sentences, say what Population ecology is doing here, from the situation to the result.
In other words — as if you have never seen this before
Population ecology. Population size is how many. Density is how many in a given area. Growth often starts slow, becomes fast, then levels off at the carrying capacity, the number the place can support. Limiting factors include food, water, space, disease and predators. Predator and prey numbers rise and fall out of step: more prey, then more predators, then fewer prey, then fewer predators.
2. What do we already know?
Quelea on grain, or goats on an overstocked village veld, is carrying capacity you can see.
3. Which method — and why this one?
Population ecology. Population size is how many. Density is how many in a given area. Growth often starts slow, becomes fast, then levels off at the carrying capacity, the number the place can support. Limiting factors include food, water, space, disease and predators. Predator and prey numbers rise and fall out of step: more prey, then more predators, then fewer prey, then fewer predators.
4. Step-by-step working
01 / 07
What it is
Population ecology is how a group of one species changes in number, and what stops it growing forever.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
Population size is how many. Density is how many in a given area. Growth often starts slow, becomes fast, then levels off at the carrying capacity, the number the place can support. Limiting factors include food, water, space, disease and predators. Predator and prey numbers rise and fall out of step: more prey, then more predators, then fewer prey, then fewer predators.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. Quelea birds on a grain field. One season the grain is rich, so the flock grows quickly. The field cannot feed an endless flock. When grain runs out, deaths and departures rise and the flock stops growing. That levelling is carrying capacity, not a decision by the birds to be tidy. If a predator increases after the flock peaks, the prey curve falls next. A drought is a limiting factor even if no predator is involved. Counting birds in sample plots and scaling up is an estimate, not a photograph of every bird.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Copy onto your answer sheet — in this order
Answer: Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to think a population can grow exponentially forever in a real field, or to call all the species in the field one population.
14 · 4 Marks · Human impact on the environment
Life Sciences Grade 11. Use this case. Day Zero and a mine dump. Cape Town’s Day Zero scare was a city using water faster than the catchment refilled. The rain cycle had not stopped. The dams had. On the Witwatersrand, water running off old mine dumps is acidic and carries metals into streams. Fish die downstream of the dump and not above it. Both are human impact. One is volume. One is poison. Neither is the natural greenhouse effect, which would be there with no city and no mine. In sentences, say what Human impact on the environment is doing here, from the situation to the result.
Human impact on the environment
Notes: Wattles in a catchment, and a fish kill below a sewage leak, are the South African cases.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Life Sciences Grade 11. Use this case. Day Zero and a mine dump. Cape Town’s Day Zero scare was a city using water faster than the catchment refilled. The rain cycle had not stopped. The dams had. On the Witwatersrand, water running off old mine dumps is acidic and carries metals into streams. Fish die downstream of the dump and not above it. Both are human impact. One is volume. One is poison. Neither is the natural greenhouse effect, which would be there with no city and no mine. In sentences, say what Human impact on the environment is doing here, from the situation to the result.
In other words — as if you have never seen this before
Human impact on the environment. The natural greenhouse effect keeps Earth warm enough for life. Burning fossil fuels and cutting forests add extra carbon dioxide, so more heat is trapped. That is the enhanced greenhouse effect. Alien plants outcompete local ones and drink scarce water. Sewage and fertiliser in a river feed algae, which then die and the decay uses up oxygen. Carbon footprint is the greenhouse gas a person or a process is responsible for. Conservation is not only “being nice”. It is keeping the processes, such as clean water and pollination, that people also need.
2. What do we already know?
Wattles in a catchment, and a fish kill below a sewage leak, are the South African cases.
3. Which method — and why this one?
Human impact on the environment. The natural greenhouse effect keeps Earth warm enough for life. Burning fossil fuels and cutting forests add extra carbon dioxide, so more heat is trapped. That is the enhanced greenhouse effect. Alien plants outcompete local ones and drink scarce water. Sewage and fertiliser in a river feed algae, which then die and the decay uses up oxygen. Carbon footprint is the greenhouse gas a person or a process is responsible for. Conservation is not only “being nice”. It is keeping the processes, such as clean water and pollination, that people also need.
4. Step-by-step working
01 / 07
What it is
Human impact is the set of ways people change air, water, soil and other species, and what can still be done about it.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 07
How it works
The natural greenhouse effect keeps Earth warm enough for life. Burning fossil fuels and cutting forests add extra carbon dioxide, so more heat is trapped. That is the enhanced greenhouse effect. Alien plants outcompete local ones and drink scarce water. Sewage and fertiliser in a river feed algae, which then die and the decay uses up oxygen. Carbon footprint is the greenhouse gas a person or a process is responsible for. Conservation is not only “being nice”. It is keeping the processes, such as clean water and pollination, that people also need.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 07
Worked theory
Worked theory. A river below an informal settlement and a ploughed field. Pit latrines and fertiliser both add nutrients. Algae bloom. When they rot, oxygen falls and fish die. Upstream of the settlement the same river still holds fish. The difference is the input, not a change in the definition of a river. On the bank, invasive wattle shades out grassland and uses deep water. Clearing the wattle is a human impact in the other direction. Switching a school’s lights off does not fix a river, but it is the same idea at the scale of a carbon footprint: less waste, less damage.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 07
Say it back
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Copy onto your answer sheet — in this order
Answer: Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
6. Check it like a marker
The answer names the situation, what changed, and the result. It does not stop at a heading.
7. A trap first-timers fall into
A common mix-up is to treat the greenhouse effect itself as pollution, or to call a local indigenous tree an alien invader.
15 · 2 Marks · Cellular respiration
Worked theory. A learner sprints, then walks. During the sprint the muscle mitochondria cannot get oxygen fast enough, so some glucose is broken down anaerobically and lactic acid builds. That is the burn. In the walk, oxygen catches up and the lactic acid is dealt with. The same learner’s cells were already doing aerobic respiration before the sprint. Plants do this too, in their mitochondria, including at night when they cannot photosynthesise. A breathing rate going up is the supply line, not the reaction itself. What does this case show about Cellular respiration?
Cellular respiration
Notes: Cellular respiration is how cells release energy from glucose. It is not the same thing as breathing.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Worked theory. A learner sprints, then walks. During the sprint the muscle mitochondria cannot get oxygen fast enough, so some glucose is broken down anaerobically and lactic acid builds. That is the burn. In the walk, oxygen catches up and the lactic acid is dealt with. The same learner’s cells were already doing aerobic respiration before the sprint. Plants do this too, in their mitochondria, including at night when they cannot photosynthesise. A breathing rate going up is the supply line, not the reaction itself. What does this case show about Cellular respiration?
In other words — as if you have never seen this before
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
2. What do we already know?
Cellular respiration is how cells release energy from glucose. It is not the same thing as breathing.
3. Which method — and why this one?
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Cellular respiration is how cells release energy from glucose. It is not the same thing as breathing.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Aerobic respiration needs oxygen and happens mostly in mitochondria: glucose + oxygen gives carbon dioxide + water + a usable packet of energy, ATP. Anaerobic respiration in human muscle has no oxygen and ends in lactic acid, with far less ATP. Yeast’s anaerobic path makes ethanol and carbon dioxide. Breathing only brings the oxygen in and the carbon dioxide out. The energy release is inside the cell.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Copy onto your answer sheet — in this order
Answer: Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
16 · 2 Marks · Human impact on the environment
Worked theory. A river below an informal settlement and a ploughed field. Pit latrines and fertiliser both add nutrients. Algae bloom. When they rot, oxygen falls and fish die. Upstream of the settlement the same river still holds fish. The difference is the input, not a change in the definition of a river. On the bank, invasive wattle shades out grassland and uses deep water. Clearing the wattle is a human impact in the other direction. Switching a school’s lights off does not fix a river, but it is the same idea at the scale of a carbon footprint: less waste, less damage. What does this case show about Human impact on the environment?
Human impact on the environment
Notes: Human impact is the set of ways people change air, water, soil and other species, and what can still be done about it.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Worked theory. A river below an informal settlement and a ploughed field. Pit latrines and fertiliser both add nutrients. Algae bloom. When they rot, oxygen falls and fish die. Upstream of the settlement the same river still holds fish. The difference is the input, not a change in the definition of a river. On the bank, invasive wattle shades out grassland and uses deep water. Clearing the wattle is a human impact in the other direction. Switching a school’s lights off does not fix a river, but it is the same idea at the scale of a carbon footprint: less waste, less damage. What does this case show about Human impact on the environment?
In other words — as if you have never seen this before
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
2. What do we already know?
Human impact is the set of ways people change air, water, soil and other species, and what can still be done about it.
3. Which method — and why this one?
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Human impact is the set of ways people change air, water, soil and other species, and what can still be done about it.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
The natural greenhouse effect keeps Earth warm enough for life. Burning fossil fuels and cutting forests add extra carbon dioxide, so more heat is trapped. That is the enhanced greenhouse effect. Alien plants outcompete local ones and drink scarce water. Sewage and fertiliser in a river feed algae, which then die and the decay uses up oxygen. Carbon footprint is the greenhouse gas a person or a process is responsible for. Conservation is not only “being nice”. It is keeping the processes, such as clean water and pollination, that people also need.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Copy onto your answer sheet — in this order
Answer: Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
17 · 2 Marks · Photosynthesis
What is the answer to keep for Photosynthesis?
Photosynthesis
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: What is the answer to keep for Photosynthesis?
In other words — as if you have never seen this before
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Copy onto your answer sheet — in this order
Answer: Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
18 · 2 Marks · Population ecology
What is the answer to keep for Population ecology?
Population ecology
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: What is the answer to keep for Population ecology?
In other words — as if you have never seen this before
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Copy onto your answer sheet — in this order
Answer: Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
19 · 2 Marks · Excretion in humans
What is the answer to keep for Excretion in humans?
Excretion in humans
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: What is the answer to keep for Excretion in humans?
In other words — as if you have never seen this before
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Copy onto your answer sheet — in this order
Answer: The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
20 · 2 Marks · Gaseous exchange
What is the answer to keep for Gaseous exchange?
Gaseous exchange
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: What is the answer to keep for Gaseous exchange?
In other words — as if you have never seen this before
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Copy onto your answer sheet — in this order
Answer: Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
21 · 2 Marks · Human impact on the environment
What is the answer to keep for Human impact on the environment?
Human impact on the environment
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: What is the answer to keep for Human impact on the environment?
In other words — as if you have never seen this before
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
Copy onto your answer sheet — in this order
Answer: Enhanced greenhouse effect, invasive species, and polluted water are human impacts. The natural greenhouse effect is not the problem. The extra is.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
22 · 2 Marks · Gaseous exchange
Worked theory. Air enters, the chest expands, alveoli fill. Oxygen crosses into a red blood cell and is carried away. Carbon dioxide crosses out. If the alveoli fill with fluid, or if smoke destroys their walls so the surface shrinks, diffusion fails even though the person is still trying to breathe. A fish uses gills for the same idea: thin, moist, large surface, close to blood. The organ changes. The principle does not. Holding your breath stops the fresh supply. It does not stop the cells needing oxygen. What does this case show about Gaseous exchange?
Gaseous exchange
Notes: Gaseous exchange is the diffusion of oxygen into the blood and carbon dioxide out of it, across a thin, moist, large surface.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Worked theory. Air enters, the chest expands, alveoli fill. Oxygen crosses into a red blood cell and is carried away. Carbon dioxide crosses out. If the alveoli fill with fluid, or if smoke destroys their walls so the surface shrinks, diffusion fails even though the person is still trying to breathe. A fish uses gills for the same idea: thin, moist, large surface, close to blood. The organ changes. The principle does not. Holding your breath stops the fresh supply. It does not stop the cells needing oxygen. What does this case show about Gaseous exchange?
In other words — as if you have never seen this before
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
2. What do we already know?
Gaseous exchange is the diffusion of oxygen into the blood and carbon dioxide out of it, across a thin, moist, large surface.
3. Which method — and why this one?
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Gaseous exchange is the diffusion of oxygen into the blood and carbon dioxide out of it, across a thin, moist, large surface.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
In humans that surface is the alveoli in the lungs. Each alveolus is one cell thick, wrapped in capillaries. Inhaled air is high in oxygen, so oxygen diffuses into the blood. Blood arriving from the body is high in carbon dioxide, so carbon dioxide diffuses into the air to be exhaled. Breathing moves the air. Gaseous exchange is the diffusion. The tubes of the lung do not do the exchange. The alveoli do.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
Copy onto your answer sheet — in this order
Answer: Gaseous exchange is diffusion at the alveoli. Breathing is the ventilation that keeps the air fresh. The surface must stay thin, moist and large.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
23 · 2 Marks · Animal nutrition
What is the answer to keep for Animal nutrition?
Animal nutrition
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: What is the answer to keep for Animal nutrition?
In other words — as if you have never seen this before
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Copy onto your answer sheet — in this order
Answer: Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
24 · 2 Marks · Excretion in humans
Worked theory. A learner who has played in the sun and not drunk. Blood is too concentrated. ADH rises. The collecting ducts reabsorb more water. Urine comes out small in volume and dark. After a litre of water, ADH falls, less water is reabsorbed, and urine is pale and plentiful. Glucose in the urine is not normal. It means the tubule could not reabsorb all of it, which is a sign to test for, not a usual step of the nephron. The kidney did not “make” urea. The liver made urea from excess amino acids. The kidney only removed it. What does this case show about Excretion in humans?
Excretion in humans
Notes: Excretion is the removal of metabolic waste. In humans the kidney is the organ that clears urea and balances water and salts.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Worked theory. A learner who has played in the sun and not drunk. Blood is too concentrated. ADH rises. The collecting ducts reabsorb more water. Urine comes out small in volume and dark. After a litre of water, ADH falls, less water is reabsorbed, and urine is pale and plentiful. Glucose in the urine is not normal. It means the tubule could not reabsorb all of it, which is a sign to test for, not a usual step of the nephron. The kidney did not “make” urea. The liver made urea from excess amino acids. The kidney only removed it. What does this case show about Excretion in humans?
In other words — as if you have never seen this before
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
2. What do we already know?
Excretion is the removal of metabolic waste. In humans the kidney is the organ that clears urea and balances water and salts.
3. Which method — and why this one?
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Excretion is the removal of metabolic waste. In humans the kidney is the organ that clears urea and balances water and salts.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Blood reaches the nephron under pressure. At the glomerulus, water, urea, glucose and salts are filtered. Large proteins and blood cells stay in the blood. Along the tubule, all the glucose and the salts and water the body still needs are reabsorbed. Urea stays in the fluid and becomes urine. ADH, from the pituitary, makes the collecting duct keep more water when the blood is too concentrated. Sweat and exhaled carbon dioxide are also excretion. Faeces are not. Faeces were never inside the body’s cells as metabolic waste.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
Copy onto your answer sheet — in this order
Answer: The nephron filters, then reabsorbs what the body keeps, and lets urea leave. ADH saves water. Faeces are egestion, not excretion.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
25 · 2 Marks · Cellular respiration
What is the answer to keep for Cellular respiration?
Cellular respiration
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: What is the answer to keep for Cellular respiration?
In other words — as if you have never seen this before
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
Copy onto your answer sheet — in this order
Answer: Aerobic respiration in mitochondria uses glucose and oxygen and pays out ATP. Anaerobic respiration is the short, costly backup. Breathing is only the gas supply.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
26 · 2 Marks · Population ecology
Worked theory. Quelea birds on a grain field. One season the grain is rich, so the flock grows quickly. The field cannot feed an endless flock. When grain runs out, deaths and departures rise and the flock stops growing. That levelling is carrying capacity, not a decision by the birds to be tidy. If a predator increases after the flock peaks, the prey curve falls next. A drought is a limiting factor even if no predator is involved. Counting birds in sample plots and scaling up is an estimate, not a photograph of every bird. What does this case show about Population ecology?
Population ecology
Notes: Population ecology is how a group of one species changes in number, and what stops it growing forever.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Worked theory. Quelea birds on a grain field. One season the grain is rich, so the flock grows quickly. The field cannot feed an endless flock. When grain runs out, deaths and departures rise and the flock stops growing. That levelling is carrying capacity, not a decision by the birds to be tidy. If a predator increases after the flock peaks, the prey curve falls next. A drought is a limiting factor even if no predator is involved. Counting birds in sample plots and scaling up is an estimate, not a photograph of every bird. What does this case show about Population ecology?
In other words — as if you have never seen this before
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
2. What do we already know?
Population ecology is how a group of one species changes in number, and what stops it growing forever.
3. Which method — and why this one?
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Population ecology is how a group of one species changes in number, and what stops it growing forever.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Population size is how many. Density is how many in a given area. Growth often starts slow, becomes fast, then levels off at the carrying capacity, the number the place can support. Limiting factors include food, water, space, disease and predators. Predator and prey numbers rise and fall out of step: more prey, then more predators, then fewer prey, then fewer predators.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
Copy onto your answer sheet — in this order
Answer: Populations grow, then level at carrying capacity. Food, space, disease and predators limit them. Predator and prey numbers chase each other.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
27 · 2 Marks · Photosynthesis
Worked theory. A spinach leaf in sun on a Pretoria windowsill. Light hits the palisade cells. Water has come up the xylem. Carbon dioxide enters through open stomata. Glucose is made and can be stored as starch. At night the light is gone, so photosynthesis stops, even though the leaf is still alive. The same leaf will still respire at night. Cover the leaf with foil and test later with iodine: the covered part stays brown, the lit part goes blue-black. No light, no new starch. What does this case show about Photosynthesis?
Photosynthesis
Notes: Photosynthesis is how green plants store light energy as glucose, using carbon dioxide and water, and releasing oxygen.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Worked theory. A spinach leaf in sun on a Pretoria windowsill. Light hits the palisade cells. Water has come up the xylem. Carbon dioxide enters through open stomata. Glucose is made and can be stored as starch. At night the light is gone, so photosynthesis stops, even though the leaf is still alive. The same leaf will still respire at night. Cover the leaf with foil and test later with iodine: the covered part stays brown, the lit part goes blue-black. No light, no new starch. What does this case show about Photosynthesis?
In other words — as if you have never seen this before
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
2. What do we already know?
Photosynthesis is how green plants store light energy as glucose, using carbon dioxide and water, and releasing oxygen.
3. Which method — and why this one?
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Photosynthesis is how green plants store light energy as glucose, using carbon dioxide and water, and releasing oxygen.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
It happens in chloroplasts. Chlorophyll absorbs the light. In the light-dependent part, light splits water and oxygen is given off. In the light-independent part, carbon dioxide is built into glucose. The word equation is carbon dioxide + water, with light and chlorophyll, gives glucose + oxygen. A leaf is thin, broad and full of stomata so that light and carbon dioxide can reach the chloroplasts.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
Copy onto your answer sheet — in this order
Answer: Photosynthesis, in chloroplasts, uses light, water and carbon dioxide to make glucose and oxygen. No light means it stops.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
28 · 2 Marks · Animal nutrition
Worked theory. A cheese sandwich. Starch in the bread meets amylase in the mouth. Protein in the cheese is attacked in the stomach and finished in the small intestine. Fat in the cheese is emulsified by bile, then lipase splits it. Glucose and amino acids cross the villi into the blood. Fatty products enter the lymph. Fibre continues and is egested. If the villi were flattened, as in untreated coeliac disease, the food could be digested and still not absorbed. Digestion and absorption are two different events. What does this case show about Animal nutrition?
Animal nutrition
Notes: Animal nutrition is how a human takes food in, breaks it down, absorbs the useful molecules, and egests what cannot be used.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Worked theory. A cheese sandwich. Starch in the bread meets amylase in the mouth. Protein in the cheese is attacked in the stomach and finished in the small intestine. Fat in the cheese is emulsified by bile, then lipase splits it. Glucose and amino acids cross the villi into the blood. Fatty products enter the lymph. Fibre continues and is egested. If the villi were flattened, as in untreated coeliac disease, the food could be digested and still not absorbed. Digestion and absorption are two different events. What does this case show about Animal nutrition?
In other words — as if you have never seen this before
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
2. What do we already know?
Animal nutrition is how a human takes food in, breaks it down, absorbs the useful molecules, and egests what cannot be used.
3. Which method — and why this one?
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Animal nutrition is how a human takes food in, breaks it down, absorbs the useful molecules, and egests what cannot be used.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
The path is mouth, oesophagus, stomach, small intestine, large intestine, anus. Teeth and saliva start starch digestion. The stomach’s acid and protease start protein. The liver makes bile, which emulsifies fats. The pancreas adds enzymes for starch, protein and fat. The small intestine’s villi give a huge surface for absorption into the blood. The large intestine takes back water. Egestion is not excretion. Excretion removes metabolic waste such as urea.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
Copy onto your answer sheet — in this order
Answer: Ingestion, digestion, absorption, assimilation, egestion. Villi absorb. Bile is not an enzyme. Egestion is not excretion.
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”