A pure breeding pea plant with the dominant phenotype of character A and recessive phenotype of character B was crossed with another pure breeding plant with the recessive phenotype of character A and dominant phenotype character B. Offspring of this cross was crossed with a homozygous recessive for both the characters A and B. The following results were obtained. 

22 were phenotypically dominant of A and recessive of B

22 were phenotypically recessive for both A and B

22 were phenotypically recessive for A and dominant for B

22 were phenotypically dominant for both A and B 

The results show that 

(1) genes A and B are linked

(2) independent segregation of genes A and B

(3) Mendelian dihybrid inheritance

(4) polygenic inheritance.

Which of the following is not a X-linked recessive disease?

(1) Haemophilia 

(2) Colour blindness

(3) β thalassemia

(4) Glucose-6-phosphate dehydrogenase deficiency.

A pure tall red plant is crossed with a pure dwarf white plant. The progenies thus produced in F₁ generations are selfed. The different types of gametes that will be produed in F₂ generaion will be

(1) 2

(2) 4

(3) 8

(4) 16

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