Agricultural Science
What you must understand
This domain covers the biology underpinning farming. Know plant parts and functions - root, stem, leaf, flower, fruit, seed - and processes: photosynthesis (light + carbon dioxide + water → sugar + oxygen), respiration, transpiration, translocation and osmosis. Understand seed structure and germination requirements (water, oxygen, suitable temperature, sometimes light). Know plant nutrients: macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium, sulphur) and micronutrients, and their deficiency symptoms - nitrogen gives pale older leaves, phosphorus poor roots and purple tints, potassium scorched leaf edges. Learn animal biology basics: digestion in ruminants versus monogastrics, the role of the rumen, and the meaning of heredity and selection in breeding. Understand ecological concepts: food chains, pollination, and the role of beneficial insects.
Traps in questions
- Confusing photosynthesis (makes food) with respiration (releases energy, day and night).
- Thinking plants take nitrogen from the air directly; legumes fix nitrogen via bacteria in root nodules.
- Mixing up macro- and micronutrients by quantity needed, not importance.
- Assuming all animals chew cud; only ruminants do.
- Forgetting that seeds need oxygen; waterlogged seed beds rot.
Worked example
A leaf shows yellowing between veins on older leaves while veins stay green. Older leaves move mobile nutrients such as nitrogen and magnesium to young growth, so the symptom points to a mobile-nutrient deficiency, commonly magnesium in this pattern. Rule of thumb: symptoms on old leaves = mobile nutrient (N, P, K, Mg); symptoms on new leaves = immobile nutrient (calcium, iron, boron).