Principles of Inheritance and Variation — Page 13 | NEET Biology

Q121

How many base pairs are found in one genome of man?

A 7×10^4

B 2.8×10^7

C 3×10^9

D 4×10^9

Correct Answer

Option C

Solution

(c) The human haploid genome contains approximately 3×10^9 base pairs.

Q122

In hybridisation Tt x tt gives rise to progeny ratio

A 1:1

B 1:2

C 2:1

D 1:2:1

Correct Answer

Option A

Solution

(a) Tt x tt gives 1 Tt : 1 tt = 1:1.

Q123

Which character studied by Mendel in garden pea was dominant

A Wrinkled seed shape

B Pod colour (green pods)

C Green seed colour

D Terminal flower position

Correct Answer

Option B

Solution

(b) Green pod colour is dominant over yellow; round seed is dominant over wrinkled; yellow seed is dominant over green; axial is dominant over terminal.

Q124

Which one pair of the following parents is most likely to get a child with hemolytic disease of newborn?

A Rh-negative mother and Rh-positive father

B Rh-positive mother and Rh-negative father

C Rh-negative mother and Rh-negative father

D Rh-positive mother and Rh-positive father

Correct Answer

Option A

Solution

(a) Rh- mother carrying Rh+ fetus develops anti-Rh antibodies causing hemolytic disease of newborn.

Q125

Probability of four sons to a couple is

A 1/4

B 1/8

C 1/16

D 1/32

Correct Answer

Option C

Solution

(c) P(son)=1/2; P(four sons)=(1/2)^4=1/16.

Q126

Two non-allelic genes produce new phenotype when present together but fail to do so independently. They are called

A Epistasis

B Polygene

C Non-complementary genes

D Complementary genes

Correct Answer

Option D

Solution

(d) Complementary genes require both to be present (dominant) to produce the new phenotype.

Q127

Independent assortment of genes does not take place when

A genes are located on homologous chromosomes

B genes are linked and located on same chromosomes

C genes are located on nonhomologous chromosomes

D all the above

Correct Answer

Option B

Solution

(b) Linked genes on the same chromosome do not show independent assortment.

Q128

A gene is said to be dominant if

A it expresses its effect only in homozygous state

B it expresses its effect only in heterozygous condition

C it expresses its effect both in homozygous and heterozygous condition

D it never expresses its effect

Correct Answer

Option C

Solution

(c) A dominant allele expresses its phenotype in both homozygous and heterozygous conditions.

Q129

Albinism is autosomal recessive. First child of normally pigmented couple is an albino. Probability that second child will also be an albino is

A 25%

B 50%

C 75%

D 100%

Correct Answer

Option A

Solution

(a) Both parents are Aa; P(albino) = 1/4 = 25% for each subsequent child independently.

Q130

A woman with two genes for haemophilia and a gene for colour blindness on one X chromosome marries a normal man. How will the progeny be?

A haemophilic and colour-blind daughters

B 50% haemophilic colour-blind sons and 50% haemophilic sons

C 50% haemophilic daughters and 50% colour-blind daughters

D All sons and daughters haemophilic and colour-blind

Correct Answer

Option B

Solution

(b) Woman is X^hc X^h × XY: sons get either X^hc (haemophilic+colour blind) or X^h (haemophilic only).