Plants: Structures, Growth and Reproduction
This domain tests plant structure and function, photosynthesis, water transport and how flowering plants reproduce and scatter seeds.
Leaves, roots and transport
Root hair cells have a large surface area to absorb water and mineral salts. Xylem vessels carry water and minerals upwards from the root; phloem tubes carry dissolved sugar away from the leaves. In the leaf, palisade cells packed with chloroplasts carry out photosynthesis, and stomata allow carbon dioxide in and oxygen and water vapour out. Guard cells open and close each stoma.
Photosynthesis: carbon dioxide + water → glucose + oxygen, using light energy trapped by chlorophyll. Glucose is used for growth or stored as starch.
Flowers, fruits and seeds
Sepals protect the bud and petals attract insects. The stamen has an anther (makes pollen) and filament; the carpel has a stigma, style and ovary containing ovules. Pollination is the transfer of pollen to a stigma. Fertilisation joins the pollen nucleus with an ovule nucleus; the ovary then becomes the fruit and ovules become seeds. Seeds are dispersed by wind, water, animals or explosive pods.
Worked example
A bean plant kept in a dark cupboard with water goes pale and stops growing taller. Reason: without light, chlorophyll is not made and photosynthesis cannot supply glucose, so growth slows; the plant still respires and uses stored food.
Traps that cost marks
Do not say plants 'eat' soil - they absorb mineral salts, not food. Transpiration is water loss, not sugar transport. Seeds germinate with water, warmth and oxygen; light is needed only after the shoot appears.