(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 ]
Explanation
(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
