Which of the following chromosomal disorders is the commonest in the new borns?

(1) Edward's syndrome

(2) Patau's syndrome

(3) Down's syndrome

(4) None of these. 

An inherited character and its detectable variant is termed as

(1) unit factor

(2) trait

(3) genetic profile

(4) genotypic charcter

A diagramatic representation of karyotype of a species is referred to as its

(1) idiogram

(2) hologram

(3) karyogram

(4) Both 1 and 3

Which of the following is not an autosomal genetic disorder ?

(1) Sickle-cell anaemia

(2) Cystic fibrosis

(3) Haemophilia

(4) Huntington's disease

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.