ABO blood grouping is controlled by gene I which has three alleles and shows co-dominance. There are six genotypes. How many phenotypes in all are possible?

1.	three	2.	four
3.	five	4.	six

The fruit fly Drosophila melanogaster was found to be very suitable for experimental verification of the chromosomal theory of inheritance by Morgan and his colleagues because:

Which one of the following conditions of the zygotic cell would lead to the birth of a normal human female child?

1. one X and one Y chromosome
2. two X chromosomes
3. only one Y chromosome
4. only one X chromosome

Test cross in plants or in Drosophila involves crossing:
1. between two genotypes with dominant trait
2. between two genotypes with recessive trait
3. between two F₁ hybrids
4. the F₁ hybrid with a double recessive genotype

A cross in which an organism showing a dominant phenotype in crossed with the recessive parent in order to know its genotype is called:

1. Back cross

2. Test cross

3. Dihybrid cross

4. Monohybrid cross

In antirrhinum, two plants with pink flowers were hybridized. The F₁ plants produced red, pink, and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridization? Red flower colour is determined by RR, and White by rr genes.

A test cross is carried out to:

In order to find out the different types of gametes produced by a pea plant having the genotype AaBb, it should be crossed to a plant with the genotype:

1. AaBb

2. aabb

3. AABB

4. aaBB

Which of the following is not a hereditary disease:

1. Haemophilia

2. Cretinism

3. Cystic fibrosis

4. Thalasasemia 

Haemophilia is more commonly seen in human males than in human females because: