Principles of Inheritance and Variation

Phenotype of an organism is the result of-

1. Environmental changes and sexual dimorphism
2. Cytoplasmic effects and nutrition
3. Genotype and environment interactions
4. Mutations and linkages

Which one of the following is an example of polygenic inheritance?

1. Skin colour in humans
2. Pod shape in garden pea
3. Production of male honey bee
4. Flower colour in Mirabilis jalapa

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

G-6-P dehydrogenase deficiency is associated with haemolysis of -

1. RBCs
2. Lymphocytes
3. Platelets
4. Leucocytes

A man and a woman, who do not show any apparent signs of a certain inherited disease, have seven children (2 daughters and 5 sons). Three of the sons suffer from the given disease but none of the daughters are affected. Which of the following mode of inheritance do you suggest for this disease?

1. Autosomal dominant
2. Sex-linked recessive
3. Sex-linked dominant
4. Sex-limited recessive

A woman with 47 chromosomes due to three copies of chromosome 21 is characterized by -

1. Superfemaleness
2. Turner's syndrome
3. Triploidy
4. Down's syndrome

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

1. This disease is due to an X-linked dominant mutation
2. This disease is due to a Y-linked recessive mutation
3. This disease is due to an X-linked recessive mutation
4. A greater proportion of girls die in infancy

Which of the following is not a hereditary disease?

1. Cretinism
2. Cystic fibrosis
3. Haemophilia
4. Thalassemia

A woman with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. This boy -

1. May be colour blind or may have normal vision
2. Must have normal colour vision
3. Must be colour blind
4. Will be partially colour blind since he is heterozygous for the colour blind mutant allele.

A woman with 47 chromosomes due to three copies of chromosome 21 is characterized by

1. triploidy
2. Down’s syndrome
3. superfemaleness
4. Turner’s syndrome