ZIMSEC O-Level Biology (4025)

Plant Nutrition and Transport: notes

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Photosynthesis: carbon dioxide + water, using light energy absorbed by chlorophyll, makes glucose and oxygen.
Leaf: a thin, flat blade with chloroplasts in palisade cells and stomata for gas exchange.
Limiting factors: light intensity, carbon dioxide concentration and temperature.
Minerals: nitrate is needed for protein; magnesium for chlorophyll. Lack of nitrate gives yellow leaves.
Xylem: carries water and mineral ions up from roots. Phloem: carries sugars to where they are used or stored.
Transpiration: loss of water vapour from leaves through stomata. It rises in heat, wind and dry air.
Starch test: boil the leaf, then add iodine; blue-black means starch.