This was the most popular question. A large number of candidates that attempted it did well though some could not express themselves properly.
The expected answers are:
7 (a) (i) Courtship behaviour in Animals
- It consists of instinctive behaviors;
- in response to certain stimuli;
- from opposite sexes of same species;
- it is carried out as a series of fixed actions;
- alternatively performed by male and female;
- leading to mating
(ii) Benefits of Courtship behaviour
- It advertises the presence of sexually receptive individuals;
- it brings the male and female together;
- thereby making the female partner more responsive to the male;
- the territory acquired during courtship ensures adequate supply of food/nesting materials/safety;
- ensures that the female chooses the right male partner;
- it indicates sexual interest and not aggression; stimulates egg laying and sperm release in the partner;
- ensures fertilization as it coincides with ovulation in the female;
- it makes intraspecific mating more certain in case of closely related species.
(b) Courtship behavior in Agama Lizard
- A sexually active male lizard is large, brightly coloured/with an orange/blue head;
- female lizard is smaller and less colourful/brown with green markings;
- dominant male lizard defends its territory;
- by driving away/fighting off/lashing other males with its tail;
- male displays its full colours in front of female;
- female responds by arching her back and lifting her tail vertically;
- male tries to catch her;
- female usually runs away;
- when caught mating may take place.
(c) The mammalian placenta
- This is a mass of vascularized tissue;
- formed partly by embryonic tissue and tissues of the uterine lining/endometrium;
- it is linked to the foetus by the umbilical cord;
- which carries the umbilical artery and vein;
- it has villi which grow/project into the maternal blood spaces/haemocoels in the uterine lining;
- this brings the foetal and maternal blood supplies into very close contact without mixing.
