Question 4
(a) In an incubator, 1,500 eggs were arranged on the trays for incubation. During candling, 25 eggs were discovered to be unfertilized. At hatching, 475 chicks were male and the remaining were female. Calculate the percentage of:
(i) unfertilized eggs;
(ii) fertilized eggs;
(iii) male chicks;
(iv) female chicks. [ 6 marks]
(b) State four signs that indicate the approach of parturition in a cow. [ 4 marks ]
(c) Mention four vegetative materials that could be used in propagating ornamental
plants. [ 4 marks ]
(d) State four advantages of grafting. [ 4 marks ]
Observation
This question was poorly attempted by the candidates. In 4(a-b), majority of the candidates were unable to use the information given to calculate the percentage of unfertilized eggs, fertilized eggs, male chicks and female chicks as required in 5(a)(i-iv). Also, most of them could neither state the signs that indicate the approach of parturition in a cow nor mention the vegetative materials that could be used in propagating ornamental plants as required in 5(b) and (c) respectively. Further to this, most of them were unable to state the advantages of grafting as required in 4(d).
The expected answers include:
4(a) (i) Percentage of unfertilized eggs
25 x 100
1500 1
= 1.67%
(ii) Percentage of fertilized eggs
No of fertilized eggs 1500 – 25
= 1475
Percentage of fertilized eggs
1475 x 100
1500 1
= 98.33%
(iii) Percentage of male chicks
475 x 100
1500 1
= 31.67%
(iv) Percentage of female chicks
No of female chicks = 1500 –25 – 475
= 1000 chicks
Percentage of female chicks
1000 x 100
1500 1
= 66.67%
(b) Signs that indicate the approach of parturition in a cow
- Widening of the cervix
- Loss of appetite
- Contraction of the uterine wall
- Restlessness
- Pains
- Enlargement of the mammary gland and secretion of milk
- Swelling of the vulva with discharge
- Frequent urination
- The animal isolates itself
(c ) Vegetative materials that could be used in propagating ornamental plants
-
- Leaves e.g. Bryophyllum
- Stems e.g. stem cuttings, runners, suckers, rhizomes, tubers, corms,
stolons, buds, bulbs
-
- Roots e.g. slips
(d) Advantages of grafting
- Used to rapidly increase the number of desirable cultivars- Used to change plant form
- Used to repair damaged plant parts
- Used to propagate plants whose cuttings are difficult to root
- It is used to provide disease resistance to a susceptible but desirable cultivar
- Virus indexing : A special technique used by plant pathologists to find out whether a plant is free from virus
- Propagate plants which cannot be propagated by seeds
- To shorten the period of fruiting