Theory question 101
Plant Responses and HormonesSection A
A gardener that cultivates ornamental plants observed a delay in the flowering of the plants on the garden and then introduced bees to encourage a biological interaction between the bees and the plants, and also stimulate flowering.
Use the information to answer questions 1(a) to 1(c).
(a)(i) Name the biological process resulting from the interaction that led to the flowering of the plants. (ii) Explain briefly the process named in 1(a)(i).
(b) Mention two features each in the bees and the plants that encouraged the interaction. (i) Bees (ii) Plants
(c) Give one advantage of the plants to the bees.
(d) Mention two. (i) essential parts of a hibiscus flower; (ii) non-essential parts of a hibiscus flower.
(e) Explain briefly double fertilization in flowering plants.
(f) Give two features of the fruit of pride of Barbados that promotes its dispersal.
(g) Complete the table below.
Table columns: Fruit | Type of placentation
Rows: Cowpea; Okra; Pawpaw
Show the model answer
(a)(i) Pollination (insect pollination).
(ii) Pollination is the transfer of pollen grains from the anther to the stigma of a flower of the same species; bees visiting flowers for nectar carry pollen on their hairy bodies from flower to flower.
(b)(i) Bees, any two: hairy body to which pollen sticks; pollen baskets on the hind legs; long proboscis for sucking nectar; good colour vision/sense of smell.
(ii) Plants, any two: large, brightly coloured petals; scent; nectar and nectar guides; sticky or rough pollen; sticky stigma inside the flower.
(c) Any one: nectar as food (energy); pollen as protein food for larvae; resins/wax materials for the hive.
(d)(i) Stamens (androecium) and pistil/carpels (gynoecium).
(ii) Sepals (calyx), petals (corolla), epicalyx.
(e) The pollen tube carries two male nuclei into the embryo sac. One fuses with the egg cell to form the zygote (which becomes the embryo); the other fuses with the two polar nuclei (or definitive nucleus) to form the triploid endosperm nucleus. Two fusions occur, hence double fertilisation.
(f) Any two: the pod is dry and dehiscent; the pod walls dry unevenly and split along two lines (sutures), twisting and throwing the seeds out (explosive mechanism); seeds are small and smooth.
(g) Cowpea - marginal; Okra - axile; Pawpaw - parietal.
Name the essential parts in (d) as the reproductive organs.