(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 chi...

Answer Details

Given: 1,500 eggs incubated; 25 unfertilized; at hatching 475 chicks were male, the rest female.

(a)(i) Percentage of unfertilized eggs

\[ \frac{25}{1500} \times 100 = 1.67\% \]

(a)(ii) Percentage of fertilized eggs

Fertilized eggs = 1500 - 25 = 1475.

\[ \frac{1475}{1500} \times 100 = 98.33\% \]

(a)(iii) Percentage of male chicks

Total chicks hatched = 1475. Male = 475.

\[ \frac{475}{1475} \times 100 = 32.2\% \]

(a)(iv) Percentage of female chicks

Female = 1475 - 475 = 1000.

\[ \frac{1000}{1475} \times 100 = 67.8\% \]

(Percentages of chicks are taken on the 1,475 eggs that hatched; if taken on all 1,500 eggs, male = 31.7% and female = 66.7%.)

(b) Four signs of approaching parturition in a cow

1. Swelling/enlargement of the udder and dropping of milk (waxing of teats).
2. Swelling and reddening of the vulva with mucous discharge.
3. Restlessness and the cow isolating itself from the herd.
4. Slackening/sinking of the pelvic (tail-head) ligaments and loss of appetite.

(c) Four vegetative materials for propagating ornamental plants

1. Stem cuttings.
2. Suckers.
3. Bulbs/corms.
4. Layers (also rhizomes, offsets).

(d) Four advantages of grafting

1. The offspring is true to type and retains the good qualities of the parent.
2. It brings early maturity/fruiting.
3. It allows a disease-resistant or hardy rootstock to be combined with a high-yielding scion.
4. It is used to propagate plants that do not produce viable seeds, and to repair damaged plants.