Question 4
- Draw and label specimen L. [8 marks]
- State four observable differences between specimens L and M. [4 marks]
Observation
In part (a), majority of the candidates could not draw and label specimen L.
In part (b), few candidates were able to state four observable differences between specimens L and M.
In part (c), majority of the candidates were able to state three characteristics of specimen M which make it culturable.
The expected answers include:
(a) Drawing of specimen L (catfish)
(b) Observable differences between specimen L (Catfish) and specimen M (Tilapia)
Cat fish |
Tilapia |
Has barbels |
Does not have barbels |
Does not have scales |
Has scales |
Has big head compared to body size |
Has small head compared to body size |
Has two pairs of nostrils |
Has one pair of nostrils |
Dorsal fin is rayed |
Dorsal fin is spiny |
Has continuous/one lateral line |
Has discontinuous /broken/two lateral lines |
Cylindrical /narrow/long body |
Laterally compress/oval/deep body |
Flattened bony head |
Head tapers upwards/forms V-shape towards the upper part |
(c) Characteristics of specimen M (tilapia) which makes it culturable
- ability to breed in captivity
- hardiness/tolerates poor water quality(but not low dissolved oxygen)
- accept artificial feed
- matures early/fast maturity
- acceptable to consumers
- highly prolific/breeds easily/breeds rapidly
- utilizes natural food well/high conversion of feed.