Question 4
- A child belongs to blood group O and the mother belongs to group B. With the aid of a genetic cross, state the possible blood groups of the father. [16 marks]
- (i) Name two forms of adaptive communication in animals. [2 marks]
(ii) State two reasons why organisms communicate with one another. [2 marks]
Observation
This was a popular question among candidates. Some of the candidates that lost some marks in this question lost them to spelling errors.
In (a), many candidates could (b), some candidates interchanged the substrates the enzymes act on.
In (c), some candidates were able to state one way in which chlorophyll is important to plants and name two macroelements that are required for the formation of chlorophyll in plants. Some candidates were also able to state the deficiency symptom of each macroelement named.
In (d), some candidates could not outline the procedure for testing for starch sequentially. Candidates could not describe the technicalities involved in the process. Majority of candidates also wrote that the leaf should be boiled for several minutes instead of few seconds. Candidates also wrote ‘boiled’ alcohol instead of ‘warm’ alcohol
The expected answers are:
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Genetic Cross
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(i) Forms of adaptive communication
Sound/auditory/acoustic; visual; smell/chemical/pheromones; tactile; electrical signal; display.(ii) Reasons why organisms communicate
- For food;
- Mating/reproduction;
- Territorial defence;
- Danger/threats/predator;
- Tracking routes.