When Morgan hybridised yellow-bodied, white-eyed females to brown-bodied, red-eyed males and intercrossed their F₁ progeny, the F₂ ratio deviated very significantly from the 9:3:3:1 ratio. this can be attributed to the fact that:

(1) The genes are located on X and Y chromosomes

(2) Fruit fly has abnormal chromosomes

(3) The genes are located on the X chromosome

(4) The genes exhibit incomplete dominance

The two alleles of a gene pair are located on:

1. Homologous sites on homologous chromosomes

2. Heterologous sites on homologous chromosomes

3. Homologous sites on heterologous chromosomes

4. Heterologous sites on heretologous chromosomes

Which one of the following is the most suitable, medium for culture of Drosophila melanogaster ?

(1) Moist bread

(2) Agar agar

(3) Ripe banana

(4) Cow dung

When the two genes in a dihybrid cross are situated on the same chromosome:
1. The proportion of parental gene combinations was much higher than the non-parental type.
2. The proportion of parental gene combinations was much lesser than the non-parental type.
3. The proportion of parental gene combinations was equal to the non-parental type.
4. Only recombinants are formed.