(a) Given below are certain situations. Analyse each and describe its possible impact: (i) A population of bacteria living in temperate waters whose temperature increased by global warming. (ii) The sperm encounters the egg when it reaches the oviduct in human females. (iii) Self pollination does not occur in a flower that contains only pistil. (iv) Egg does not get fertilised in a human female. (v) When the seed is placed under appropriate condition of water and air in the soil? OR (b) Given below are certain situations. Analyse and describe what would happen when: (i) Spores are liberated from blob-like structures of the bread mould? (ii) Leaves of bryophyllum fall on wet soil? (iii) A pollen from different species land on the stigma of totally unrelated species? (iv) Copper-T is placed in the uterus of a human female? (v) Spirogyra breaks into smaller fragments upon maturation?

This question tests application of concepts from across the chapter — variation and survival (7.1.1), sexual reproduction and fertilisation in humans (7.3.3), pollination in flowers (7.3.2), menstruation (7.3.3(c)), seed germination (7.3.2), spore formation (7.2.6), vegetative propagation (7.2.5), incompatible pollination, contraception (7.3.3(d)), and fragmentation (7.2.2). Every response must be traced to the exact mechanism described in the NCERT text rather than generic biology knowledge, e.g. citing that variation is 'useful for the survival of species over time,' that fertilisation happens because 'they travel upwards and reach the oviduct where they may encounter the egg,' that a pistil-only flower cannot self-pollinate because it lacks stamens, that menstruation occurs because the unused thickened lining 'breaks and comes out through the vagina as blood and mucous,' and that germination follows once the embryo in the seed develops into a seedling 'under appropriate conditions' (water being explicit in the text; air/oxygen is added as standard supporting reasoning for respiration during germination, consistent with but not verbatim from the chapter). For part (b), spore release, vegetative propagation via Bryophyllum's leaf-margin buds, incompatible cross-species pollination failing at the pollen tube stage, Copper-T's uterine-irritation mechanism, and Spirogyra fragmentation are each drawn directly from Sections 7.2.5, 7.2.6, 7.3.2 and 7.3.3(d) of the chapter.