(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.
Explanation
(a) Pollination and Fertilization; (i) Whereas pollination is the transfer of pollen grains from the anther of a flower to the stigma of a flower; fertilization is the fusion of the male gamete/nucleus, with that of the female gamete/nucleus; to form a zygote (ii) Pollination precedes fertilization (b) Features that ensure cross pollination and Examples; (i) Dioecious plants/male and female flowers occur on separate plants e.g. pawpaw/ any correct example. (ii) Dichogamy/Male and female parts mature at different times (iii) Phragmanthera/ mistletoe; is protogynous/protandry/carpels mature before Stamens (thus separating. the reproductive structure in time) sun flower/cotton is protandrous/ stamen, mature before carpel. Crotolaria examples of ptologynous plant. Male and female parts are of different lengths/heterostyly/long style and short stamen e.g. Morinda. Moneocious plants/Male and female flowers occur on the same plant in different position e.g. Maize/Luffa/Oil palm/coconut etc (male flower at the apex matures first whereas the female flower in the axil of leaves matures later) the feathery stigma hang loosely and can catch airborne pollen grains but not from the same flower. Structure: Most flowers are so structured as to prevent self pollination since only a particular insect/animal can effect pollination; e.g. Crotalaria/CentrocemaNigna/pea/groundnut- stamens mature first shedding pollen into a sac-like tube formed by the keel honey guides on the standard which direct the bee to the sectaries and the stigma points towards entrance of keel and can only receive pollen brought in by a visiting bee. Self-incompatibility/self-sterility (certain chemicals on the surface of the stigma prevent growth in pollen tubes; of pollen grains from the same flower) e.g. Clover. Possession of brightly coloured petals attract insects e.g. Delonix, Hibiscus. Sweet smell for attraction of insects e.g. Rose flower. (c)(i) Agents of pollination are as follows (a) Insect/bat/animal/any named animal (b) Wind/Air (c) Water (ii) Features of wind dispersed fruits/ seeds (a) Seeds are almost always with floss thereby aiding its ability to be flown or be airborne. (b) Winged seeds/fruits (c) Light-weight seeds/fruits (d) Parachute/hairs.
