This question was another popular question in this section and most candidates that answered it
performed fairly well. Most candidates who answered the question omitted to say that sexual
reproduction was between organisms of the same species. Some candidates wrote it involved fission of
gametes rather than fusion of gametes and so lost the score.
In stating organs that produce sex hormones in mammals most candidates could only name two namely
testis and ovary and many candidates lost the score for testis because it was wrongly spelt. Most
candidates could not state the hormones produced.
Expected answers include:
Testes, ovary, adrenal glands, pituitary gland, placenta
Testes - Testosterone/Androgens;
Ovary - oestrogen/progesterone
Placenta - progesterone
Adrenal glands - Androgens
Pituitary gland -
Hormone/intersticial cell stimulating
Most candidates could correctly state the differences between reproduction in birds and lizard and
tabulated their answers. In answering question 2( c) most candidates could correctly state most of the
features of identical twins but could not state how they were formed. Some candidates said they were
formed from two fertilized eggs.
Formation ofIdentical twins
- One egg is released from the ovary into the oviduct; and fertilized by a sperm to form a
- The zygote divides into two embryos; which develop into two identical individuals.