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.

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.