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Plants

Plant studies

Plant studies in agriculture is the crop as a machine for food: roots, stems, leaves and flowers, and what it needs from the soil.

CAPS

Grade 10 · Agricultural Sciences · Plants

Agricultural Sciences splits animals from plants, soil and management.

  • The papers

    Paper 1 is animal nutrition, animal production, reproduction and protection. Paper 2 is soil science, plant studies, and agricultural management. Each paper is 150 marks.

  • How to write it

    Use the farming term, then the reason: a deficient mineral, a symptom, a management practice, and why it changes the yield or the health of the animal. A list with no cause does not explain.

  • How a marker reads it

    A common mix-up is to pour on any fertiliser, or to blame pests for a yellowing that is really hunger.

Data-response questions want you to read the table first. A general paragraph about farming that ignores the numbers scores as if you did not see them.

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Diagram

Worked theory

Worked theory. Two rows of spinach. One is pale yellow and stunted, on sand that has grown spinach for years with no manure. That pattern is nitrogen leaving with every harvest. A side dressing of a nitrogen source greens the new leaves. The old yellow leaves do not turn green again. They already grew short of it. If the newest leaves are fine and the old ones yellow, the nutrient can move. If the new leaves fail first, it cannot. Reading which leaves fail is the diagnosis, not a guess from the bag of fertiliser you happen to own.

More worked examples

  • Three spinach beds

    Bed 1 gets no nitrogen. Old leaves yellow, new leaves stay small. Bed 2 gets no phosphorus. The plants are stunted and the undersides look purple. Bed 3 gets no potassium. Leaf edges scorch while the middle stays green. A handful of a complete fertiliser on bed 1 greens the next leaves, not the ones already yellow. The symptom says which element. The bag you happened to buy may be the wrong one.

  • A wilted seedling at noon

    A seedling droops at noon and stands up after watering. Water entered the root hairs by osmosis, because the cell sap was more concentrated than the soil water, and turgor returned. A seedling in waterlogged soil also droops, but watering it more does not help, because the roots have no oxygen. The first wilt was a shortage. The second is a surplus. The leaves look similar. The soil in the hand tells them apart.

In ordinary words

Roots anchor and absorb. Stems carry water up and sugars down. Leaves photosynthesise. Flowers make the seed. Nitrogen makes leaves. Phosphorus helps roots and flowers. Potassium helps the plant resist disease and use water. A shortage shows in the leaf: yellowing for nitrogen, purple tints for phosphorus, scorched edges for potassium. The plant cannot tell you. The leaf does.

In South Africa

A yellow spinach row next to a green one is the school-garden version of a deficiency trial.

Part 1 / 4

What it is

Plant studies in agriculture is the crop as a machine for food: roots, stems, leaves and flowers, and what it needs from the soil.

Diagram
Diagram

More worked examples

Board walkthroughs on this topic. Open one, copy the working, then try the next.

Example 1 / 20

A seed test: 100 seeds are planted and 85 germinate. Calculate the germination percentage.

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: A seed test: 100 seeds are planted and 85 germinate. Calculate the germination percentage.

Before any working — hunt first

Given

Numbers and units already in the sentence: 100 seeds · 85 germinate. Copy each one into a column. A name without a number is not given.

Missing

After you copy the given, the letter that still has no number is missing. The paper is pointing at: the germination percentage. Circle that word — that is the missing variable.

Find

We are required to find: the germination percentage. Write that as a symbol on the left, with a question mark, before you touch a formula.

Calculate

What we need to calculate: % = germinatedtotal × 100. Then substitute the given, one line at a time, to get the germination percentage.

In other words — as if you have never seen this before

If you have never seen this before: % = germinatedtotal × 100. We will name a method in words, write the formula with no numbers, then substitute one line at a time.

2. What do we already know?

85 of 100.

3. Which method — and why this one?

%=germinatedtotal×100.

4. Step-by-step working

  1. 01 / 08

    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.

  2. 02 / 08

    Step A2 — Hunt: Given, Missing, Find, Calculate

    Given: Numbers and units already in the sentence: 100 seeds · 85 germinate. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: the germination percentage. Circle that word — that is the missing variable. Find: We are required to find: the germination percentage. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: % = germinatedtotal × 100. Then substitute the given, one line at a time, to get the germination percentage.

    Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).

  3. 03 / 08

    Step B — Write the given in a column

    85 of 100.

    Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.

  4. 04 / 08

    Step C — Name the method in words

    %=germinatedtotal×100.

    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.

  5. 05 / 08

    Divide

    85100×100=85%.

    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.

  6. 06 / 08

    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.

  7. 07 / 08

    Step F — Box the answer with its unit

    85%.

    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.

  8. 08 / 08

    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

85%.

Copy onto your answer sheet — in this order

Answer: 85%.

6. Check it like a marker

Buy seed with a known germination %.

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…”

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