Test cross involves :

(1) crossing between two geneotypes with recessive trait

(2) crossing between two F₁ hybrids

(3) crossing the F₁ hybrid with a double recessive genotype

(4) crossing between two genotypes with dominant trait

If a colourblind woman marries a normal visioned man, their sons wil be :

(1) all normal visioned

(2) one-half colourblind and one-half normal 

(3) three-fourths colourblind and one-fourth normal

(4) all colourblind

Cri-du-chat syndrome in humans is caused by the :

(1) fertilization of an XX egg by a normal Y-bearing sperm

(2) loss of half of the short arm of chromosome 5

(3) loss of half of the long arm of chromosome 5

(4) trisomy of 21st chromosome.

Sickle cell anaemia has not been eliminated from the African population because :

(1) it is controlled by recessive genes

(b) it is not a fatal disease

(3) it provides immunity against malaria

(4) it is controlled by a dominant genes

Which of the following shows linkage group in coupling phase?

(1)  $\underline{A B}$
$\overline{a b}$

(2)  $\underline{A b }$
$\overline{a B}$

(3)  $\underline{A b}$
$\overline{a b}$

(4)  $\underline{a B}$
$\overline{a b}$

Which pair is incorrect?

(1) Haemophilia - X linked recessive

(2) baldness - X- linked dominance

(3) colour blindness- X linked recessive

(4) antler in deer - sex limited.

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.

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