WAEC Biology 2012 Theory — Question 6

Model answer

(a)(i) Epigeal germination is a type of germination in which the cotyledons are carried above the soil. The hypocotyl elongates rapidly and arches upwards, moving the cotyledon above the soil. (ii) Differences — Hypogeal germination: the cotyledon remains under the soil; the epicotyl elongates faster; the cotyledon cannot photosynthesize. Epigeal germination: the cotyledon is carried above the soil; the hypocotyl elongates faster; the cotyledon photosynthesizes. (b)(i) Seed dormancy refers to the slowing down or seizure of the growth of a seed. (ii) Ways dormancy can be broken include addition of water, treatment with some enzymes, and exposure to alternating low and high temperature. (c) Advantages of using contraceptives in human populations: It prevents over-population. It controls birth rate. It prevents unwanted pregnancies. Some of them (barrier contraceptives) prevent sexually transmitted diseases. It promotes standard of living. It helps to control the size of a family.