Study the pedigree chart of a family showing the inheritance of myotonic dystrophy.

 

The trait under study is 

1. dominant X-linked

2. recessive X-linked

3. autosomal dominant

4. recessive Y-linked.

The ratio in a dihybrid test cross between two individuals is given by

(1) 2:1

(2) 1:2:1

(3) 3:1

(4) 1:1:1:1

A point mutation comprising the substitution of a purine by pyrimidine is called

(1) transition

(2) translocation

(3) deletion

(4) transversion

Pure line breed refers to

(1) heterozygosity only

(2) heterogyzosity and linkage

(3) homozygosity only

(4) homozygosity and self assortment.

One of the genes present exclusively on the X-chromosome in humans is concerned with

1. baldness

2. red-green colour blindness

3. facial hair/moustaches in males

4. night blindness

Given below is a pedigree chart of a family with five children. It shows the inheritance of attached ear-lobes as opposed to the free ones. The squares represent the male individuals and circles the females individuals. Which one of the foloowing conclusions drawn is correct?

(1) The parents are homozygous recessive.

(2) The trait is Y-linked.

(3) The parents are homozygous dominant.

(4) The parents are heterozygous.

How many different types of gametes can be formed by F₁ progeny, resulting from the following cross:

AA BB CC X aa bb cc

(1) 3

(2) 8

(3) 27

(4) 64

Given below is a pedigree chart showing the inheritance of a certain sex-liniked trait in humans. 

The Trait traced in the above pedigree chart is 

(1) dominant X-linked 

(2) recessive X-linked

(3) dominant Y-linked

(4) recessive Y-linked

The "cri-du-chat" syndrome is caused by change in chromosome structure invloving

(1) deletion

(2) duplication

(3) inversion

(4) translocation

Grain colour in wheat is determined by three pairs of polygenes. Following the cross AABBCC (dark colour) X aabbcc (light colour), in F₂ generation what proportion of the progeny is likely to resemble either parent?

(1) None

(2) Less than 5 percent

(3) One third

(4) Half