Principles of Inheritance and Variation

NEET Biology · 167 questions · Page 10 of 17 · Click an option or "Show Solution" to reveal answer

Q91

Haemophilia is more commonly seen in human males because it is

A Recessive character carried by Y chromosome

B Dominant character carried by X

C Dominant trait carried by Y

D Recessive trait carried by X chromosome

Correct Answer

Option D

Solution

(d) Haemophilia is X-linked recessive; males with one X chromosome express the recessive gene.

Q92

Which of the following is not a hereditary disease?

A Cystic fibrosis

B Thalassemia

C Haemophilia

D Cretinism

Correct Answer

Option D

Solution

(d) Cretinism is caused by thyroid hormone deficiency — not a hereditary genetic disease.

Q93

Sickle cell anaemia has not been eliminated from African population because

A it is not a fatal disease

B it provides immunity against malaria

C it is controlled by dominant genes

D it is controlled by recessive genes

Correct Answer

Option B

Solution

(b) Sickle cell trait (heterozygous) provides protection against Plasmodium falciparum malaria.

Q94

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

A loss of half of the short arm of chromosome 5

B loss of half of the long arm of chromosome 5

C trisomy of 21st chromosome

D fertilization of XX egg by Y sperm

Correct Answer

Option A

Solution

(a) Cri-du-chat: partial deletion of short arm of chromosome 5.

Q95

If a colour blind woman marries a normal visioned man, their sons will be

A one-half color blind and one-half normal

B three-fourths color blind and one-fourth normal

C all color blind

D all normal visioned

Correct Answer

Option C

Solution

Q96

Haploids are more suitable for mutation studies than diploids because

A haploids are more reproductively stable

B mutagens penetrate haploids more effectively

C haploids are more abundant in nature

D all mutations whether dominant or recessive are expressed in haploids

Correct Answer

Option D

Solution

(d) In haploids, every mutation (dominant or recessive) is expressed as there is no masking allele.

Q97

Klinefelter syndrome condition: 44 autosomes + XXY

A 44 autosomes + XXY

B Colour blindness - Y-linked

C Erythroblastosis foetalis - X-linked

D Down syndrome - 44 autosomes + XO

Correct Answer

Option A

Solution

(a) Klinefelter syndrome: 47,XXY karyotype — 44 autosomes + XXY sex chromosomes.

Q98

Point mutation involves

A change in single base pair

B duplication

C deletion

D insertion

Correct Answer

Option A

Solution

(a) Point mutation = change in a single base pair of DNA.

Q99

Sickle cell anemia is caused by

A substitution of valine by glutamic acid in beta globin

B change in a single base pair of DNA

C elongated sickle-shaped RBCs without a nucleus

D autosomal dominant trait

Correct Answer

Option B

Solution

(b) Sickle cell anaemia: single base change (GAG→GTG) causing glutamic acid→valine substitution.

Q100

Mutations can be induced with

A infra red radiations

B IAA

C ethylene

D gamma radiations

Correct Answer

Option D

Solution

(d) Gamma radiations are ionizing mutagens that induce gene mutations.

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