Biology - Post-UTME Study Guide
Biology in the Post-UTME tests cell biology, nutrition, respiration, transport, ecology, genetics, reproduction and health. Questions often ask you to interpret a process or a ratio rather than simply recall a definition.
Core rules
- Cell: mitochondria release energy; ribosomes make protein; chloroplasts carry out photosynthesis; the nucleus controls activity.
- Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ in the presence of light and chlorophyll.
- Aerobic respiration releases more energy than anaerobic respiration; anaerobic in muscle produces lactic acid.
- Ecology: a food chain shows energy flow; decomposers return nutrients; energy is lost at each trophic level.
- Genetics: a monohybrid cross of two heterozygotes (Tt × Tt) gives 1 TT : 2 Tt : 1 tt, i.e. 3 dominant : 1 recessive phenotype.
Worked example
Cross two heterozygous tall pea plants, Tt × Tt. The gametes are T and t from each parent. A Punnett square gives TT, Tt, Tt, tt. Three offspring show the dominant tall trait and one shows the recessive short trait, so the phenotypic ratio is 3:1. The genotypic ratio is 1:2:1.
Traps
Do not say all arteries carry oxygenated blood: the pulmonary artery carries deoxygenated blood to the lungs. Do not confuse mitosis (growth, identical cells) with meiosis (gametes, halving of chromosome number). Dominant does not mean most common in a population. Photosynthesis is not simply the reverse of respiration in every detail.