Theory question 103
Reproduction in Plants(a) Distinguish between pollination and fertilization in plants.
(b) (i) State five features which ensure cross pollination in plants. (ii) Name one plant example for each feature.
(c) (i) Name three agents of pollination (ii) State three features of wind-dispersed fruits/seeds.
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(a) Pollination is the transfer of pollen grains from the anther to the stigma; fertilization is the fusion of a male nucleus (gamete) from the pollen tube with the egg cell in the ovule to form a zygote. Pollination comes first; fertilization takes place inside the ovary.
(b) Any five with examples: dioecism – male and female flowers on separate plants (pawpaw); protandry – anthers ripen before the stigma (Hibiscus, sunflower); protogyny – stigma ripens before the anthers (Bryophyllum, grasses such as maize); self-sterility/self-incompatibility – pollen cannot fertilise the same flower (tobacco, Crotalaria); monoecism – separate male and female flowers on the same plant (maize); heterostyly – styles and stamens of different lengths (primrose); flower structure that keeps anthers and stigma apart (Hibiscus with stigma above anthers).
(c)(i) Insects; wind; water; birds; bats/other animals; man (any three).
(ii) Any three: light in weight; small in size; have wing-like outgrowths (e.g. Terminalia, Combretum); have hairs or parachutes (e.g. Tridax, cotton); produced in large numbers; dry fruits that may split open (capsules).
In (b) give the feature and a matching example for each.