Observation

 

Majority of the candidates attempted this question and their performance was average.
In part (a), majority of the candidates were able to state the uses of specimens D, E and F in fish culture. However, only few of them could draw and label specimen E.

In part (b), majority of the candidates could not state the advantages of using specimen F in fish culture.

The expected answers include:

(a) (i) Uses of specimen D (litmus paper), E (secchi disc) and F (feed pellet)
Specimen D (Litmus Paper)
- It is used to check water pH/acidity/alkalinity

Specimen E (Secchi disc)
- It is used to measure water transparency
- It is used to measure turbidity
- To measure the depth of water

Specimen F
- It is used to feed cultured fishes

(ii)An instrument in place of specimen D
- pH meter/pH scale
- pH probe/tester

(iii)Diagram of specimen E (secchi disc)


(iv)Steps involved in the use of specimen E
Secchi disc
- lower the disc into the water gradually
- note/record the depth at which the disc disappears
- allow the disc to sink to the bottom of the pond
- gradually pull up and note/record the depth at which disc just reappears
- take the average of the two readings

(b) (i)Nutrients in specimen F (feed pellets)
- carbohydrates
- protein
- fats / oil / lipids
- vitamins
- minerals/mineral salts
(ii)Advantages of using specimen F (feed pellets)
- it minimizes feed waste
- reduces water pollution
- reduces cost of feeding fish
- all nutrients are delivered/reduces nutrient loss
- the quantity of feed fed/needed is known