Principles of Inheritance and Variation — Page 12 | NEET Biology

Q111

Thalassemia is due to

A Both are due to quantitative defect in globin chain synthesis

B less synthesis of globin molecules

C Sickle cell anaemia is due to quantitative problem

D Both are due to qualitative defect

Correct Answer

Option B

Solution

(b) Thalassemia is a quantitative defect (less globin synthesized); sickle cell anaemia is a qualitative defect (abnormal globin).

Q112

In which genetic condition does each cell in the affected person have three sex chromosomes XXY?

A Turner syndrome

B Thalassemia

C Klinefelter syndrome

D Phenylketonuria

Correct Answer

Option C

Solution

(c) Klinefelter syndrome (47,XXY) affects males — small testes, gynecomastia, infertility.

Q113

Select the correct match

A Phenylketonuria - Autosomal dominant trait

B Sickle cell anaemia - Autosomal recessive trait, chromosome-11

C Thalassemia - X linked

D Haemophilia - Y linked

Correct Answer

Option B

Solution

(b) Sickle cell anaemia is autosomal recessive, caused by mutation in beta-globin gene on chromosome 11.

Q114

A child of O-group has B-group father. The genotype of father will be

A I^O I^O

B I^B I^B

C I^A I^B

D I^B I^O

Correct Answer

Option D

Solution

(d) O-group child has genotype I^O I^O; must have received I^O from father; father must be I^B I^O.

Q115

An allele is dominant if it is expressed in

A both homozygous and heterozygous states

B second generation

C heterozygous combination only

D homozygous combination only

Correct Answer

Option A

Solution

(a) A dominant allele expresses itself in both homozygous and heterozygous conditions.

Q116

A gene pair hides the effect of another. The phenomenon is

A epistasis

B dominance

C mutation

D none of the above

Correct Answer

Option A

Solution

(a) Epistasis: one gene pair suppresses the expression of a non-allelic gene pair.

Q117

How many different types of genetically different gametes will be produced by a heterozygous plant with genotype AABbCc?

A Two

B Four

C Six

D Nine

Correct Answer

Option B

Solution

(b) AABbCc: A is fixed; Bb gives B or b; Cc gives C or c → 2×2 = 4 gamete types.

Q118

How many genome types are present in a typical green plant cell?

A Two

B Three

C More than five

D More than ten

Correct Answer

Option B

Solution

(b) Three genomes: nuclear, mitochondrial, and chloroplast.

Q119

Crossing over in diploid organism is responsible for

A segregation of alleles

B dominance of genes

C linkage between genes

D recombination of linked alleles

Correct Answer

Option D

Solution

(d) Crossing over between non-sister chromatids of homologs causes recombination of linked alleles.

Q120

A woman has an X-linked condition on one of her X chromosomes. This chromosome can be inherited by

A Only daughters

B Only sons

C Both sons and daughters

D Only grandchildren

Correct Answer

Option C

Solution

(c) A woman passes one X chromosome to all children — both sons and daughters can inherit it.