Observation

This question was not popular among candidates but those that attempted it fared well only in the transmittable characters and evidence of organic evolution.

The expected answers are:

(a) (i) Sickle cell anaemia

Is an inheritable disease; caused by an abnormality in the red blood cells/haemoglobin molecules; the red blood cell of the sufferer is sickle shaped/SS genotype; while the carrier is AS genotype; causing blocking/clogging of capillaries thereby reducing the amount of oxygen it carries; causing crisis in the sufferer.

Skin colour; eye colour; blood group; height; nose shape; hair colour; albinism; haemophilism; sickle cell disease; hairy earlobe; tongue rolling; intelligence; any correctly named character.

(b) Ways by which animals survive unfavourable conditions Hibernation; aestivation; migration; basking; encystment/encapsulation.

(c)Evolutionary theories proposed by Jean Baptiste Lamarck

- Theory of use and disuse of body parts; a body part that is constantly used enlarges/becomes efficient; the one that is not becomes weak and small/atrophied; e.g. Giraffes developed long neck overtime because they fed on the crown of trees; penguins’ wings became smaller because they are not used; development of thick muscles through constant exercise.

- Inheritance of acquired traits; new species evolved after several generations by acquiring new traits and losing old ones; e.g. in Giraffes, the longer necks traits were passed to the next generation.

Evidences of organic evolution Evidence from

- comparative anatomy;

- vestigial organs;

- physiology;

- fossil records/palaeontology;

- embryology;

- cytology;

- geographical distribution;

- serology;

- comparative biochemistry;

- adaptive radiation;

- molecular records.