Down's syndrome occurs as a result of

• trisomy

• tetrasomy

• autopolyploidy

• allopolyploidy

Which of the following represents Klinefelter's syndrome?

• XX

• XO

• XY

• XXY

9: 3: 3: 1 ratio is modified to 9 : 7 ratio due to

• complementary gene

• epistatic gene

• hypostatic gene

• supplementary gene

Indicate, the inheritance of which of the following is controlled by multiple alleles?

• Colourblindness

• Sickle cell anaemia

• Blood group

• Phenylketoneuria

The absence of which clotting factor leads to haemophilia-A?

• Factor VII

• Factor VIII

• Factor IX

• Factor X

One of the following is sex-influenced character

• Appearance of beard

• Baldness in male

• Docile behaviour of female

• Low BMR in female

The map distance between the genes A and B is 3 units, between B and C is 10 units and between C and A is 7 units. The order of the genes in a linkage map constructed on the above data would perhaps be

• A, B, C 

• A, C, B

• B, C, A

• B, A, C

Which of the following conditions is related to haemophilia?

• A responsible recessive gene present in the X-chromosome

• A responsible dominant gene presentin the X-chromosome

• A responsible dominant gene present in the Y-chromosome

• A responsible dominant gene present in the autosomal chromosome

A person with the sex chromosomes XXY suffers from :

• Down's syndrome

• Turner's syndrome

• Gynandromorphism

• Klinefelter's syndrome

Which one of the following conditions in chromosome number is called monosomy?

• 2n + 1

• 2n + 2

• 2n - 1

• 2n - 2