Principles of Inheritance and Variation

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

In a plant, red fruit (R) is dominant over yellow fruit (r) and tallness (T) is dominant over shortness (t). If a plant with RRTt genotype is crossed with a plant that is rrtt

1. 75% will be tall with red fruit
2. 25% will be tall with red fruit
3. 50% will be tall with red fruit
4. All the offspring will be tall with red fruit

A male human is heterozygous for autosomal genes A and B and is also hemizygous for hemophilic gene h. What proportion of his sperms will be abh?

1. 1/16
2. 1/32
3. 1/8
4. 1/4

Lack of independent assortment of two genes A and B in fruit fly Drosophila is due to

1. Linkage
2. Recombination
3. Repulsion
4. Crossing over

One of the parents of a cross has a mutation in its mitochondria. In that cross, that parent is taken as a male. During segregation of F2 progenies that mutation is found in -

1. 50% of the progenies
2. 1/3 of the progenies
3. None of the progenies
4. All the progenies

A normal woman, whose father was colour-blind is married to a normal man. The sons would be :-

1. All colour-blind
2. 75% colour-blind
3. All normal
4. 50% colour-blind

The recessive genes located on X-chromosomes in humans are always -

1. Expressed in females
2. Sub-lethal
3. Expressed in males
4. Lethal

After a mutation at a genetic locus the character of an organism changes due to the change in :-

1. Protein synthesis pattern
2. RNA transcription pattern
3. DNA replication
4. Protein structure

In a mutational event, when adenine is replaced by guanine, it is a case of -

1. Frameshift mutation
2. Transition
3. Transversion
4. Transcription

Which one of the following traits of garden pea studied by Mendel was a recessive feature?

1. Green seed colour
2. Green pod colour
3. Axial flower position
4. Round seed shape