Biology - 生物の構造と機能・生殖と遺伝・生物の進化と環境
生物の構造と機能
Compare plant and animal cells: both have a nucleus, cytoplasm and cell membrane; plant cells also have a cell wall, chloroplasts and a large vacuole. In plants, roots absorb water and minerals, the stem conducts them, and leaves carry out photosynthesis (CO₂ + H₂O → glucose + O₂) through stomata, which also release water vapour in transpiration. In animals, learn digestion (amylase, pepsin, bile, lipase), absorption through villi, gas exchange in alveoli, circulation and kidney excretion. Classic trap: arteries carry blood away from the heart, so the pulmonary artery carries deoxygenated blood.
生殖と遺伝
Mitosis produces identical cells for growth; meiosis halves the chromosome number in gametes, and fertilisation restores it. Asexual reproduction gives clones; sexual reproduction gives variation. Genes sit on chromosomes, and dominant/recessive alleles explain Mendel's ratios.
生物の進化と環境
Evolution arises from variation plus natural selection over many generations; fossils, homologous structures and extinction patterns are evidence. In an ecosystem, producers, consumers and decomposers are linked in food chains; energy flows one way and shrinks at each level, while matter cycles.
Worked example. Cross two heterozygotes Aa × Aa with A dominant: the Punnett square gives 1 AA : 2 Aa : 1 aa, i.e. a 3 : 1 phenotype ratio. Write the gametes first, then fill the square.