Plants — Photosynthesis, Xylem vs Phloem and the Five Hormones

The Chapter That Feeds Every Other One

Plants are where the general-science section usually starts — and where a lot of candidates quietly lose marks. Not because the biology is hard, but because papers rarely ask "what is photosynthesis". They ask *which element sits at the centre of chlorophyll*, *which tissue is dead at maturity*, *which hormone is a gas*.

Three ideas carry almost every plant question:

1. 1.Photosynthesis — how a leaf turns light, water and carbon dioxide into food.
2. 2.Transport — how water climbs a thirty-metre tree, and how sugar travels back down.
3. 3.Hormones — the five chemicals that decide whether a plant grows, bends, ripens or sleeps.

Learn them as one connected story and the factual questions answer themselves. Learn them as three unrelated lists and you will swap xylem with phloem in the exam hall, as thousands do every year.

1. Which element sits at the centre of the chlorophyll molecule?

2. The dark reaction, or Calvin cycle, of photosynthesis takes place in the:

3. Which tissue carries water and dissolved minerals upward from the root to the leaf?

4. The loss of water as liquid droplets from the margins of leaves, usually at night, is called:

5. A shoot bends towards a window because of the uneven distribution of which hormone?

6. Which plant hormone is a gas at ordinary temperature?

7. Abscisic acid is called the stress hormone of plants because it:

8. Which of the following is a C₄ plant, and therefore shows almost no photorespiration?