ZIMSEC · O Level · Syllabus 4025
Biology
12 topics12 with notes
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Form 3 7 topics
- Cell structure and organisation The cell is the basic unit of life. Organisms are made of one cell (unicellular, e.g. Amoeba) or many cells (multicellular).
- Movement in and out of cells Substances move into and out of cells by diffusion, osmosis and active transport.
- Enzymes and biological molecules Food tests: iodine (starch, blue-black), Benedict's (reducing sugar, brick-red on heating), biuret (protein, purple), ethanol emulsion (fat, cloudy white).
- Plant nutrition Plants are autotrophs: they make their own food by photosynthesis.
- Animal nutrition and human digestion Ingestion → digestion → absorption → assimilation → egestion.
- 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.
Form 4 4 topicsExam year
- 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.