ZIMSEC · Form 4 · Syllabus 4025
Biology
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- Transport in plants and animals Plants Xylem: dead, hollow, lignified vessels carrying water and minerals up from roots.Phloem: living cells carrying sucrose and…
- Respiration and gas exchange Respiration releases energy from glucose in all living cells. Energy is used for movement, active transport, growth, keeping warm and building molecules.
- Excretion and homeostasis Removing waste products of metabolism: carbon dioxide (lungs), urea (kidneys), and excess water and salts.
- Coordination and response Stimulus → receptor → sensory neurone → relay neurone (in the CNS) → motor neurone → effector (muscle or gland) → response.
- Reproduction Pollination is the transfer of pollen from anther to stigma. Insect-pollinated flowers are large, scented and colourful with nectar; wind-pollinated flowers (maize, grasses) have long feathery stigmas and light, smooth pollen. After fertilisation the ovule becomes the seed and the ovary the fruit. Seeds are dispersed by animals, wind, water or explosion.
- Inheritance and genetics Females are XX, males XY. Each child has a 50% chance of being a boy.