NCERT Class 12 Biology: Chapter –5 Principle of Inheritance and Variation Part 2

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Question 10:

Which of the following will not result in variations among siblings?

a. Independent assortment of genes

b. Crossing over

c. Linkage

d. Mutation

Answer: (c)

Question 11:

Mendel’s Law of independent assortment holds good for genes situated on the:

a. non-homologous chromosomes

b. homologous chromosomes

c. extra nuclear genetic element

d. same chromosome

Answer: (a)

Question 12:

Occasionally, a single gene may express more than one effect. The phenomenon is called:

a. Multiple allelism

b. Mosaicism

c. Pleiotropy

d. Polygeny

Answer: (c)

Question 13:

In a certain taxon of insects some have 17 chromosomes and the others have 18 chromosomes. The 17 and 18 chromosome-bearing organisms are:

a. males and females, respectively

b. females and males, respectively

c. all males

d. all females

Answer: (a)

Question 14:

The inheritance pattern of a gene over generations among humans is studied by the pedigree analysis. Character studied in the pedigree analysis is equivalent to:

a. Quantitative trait

b. Mendelian trait

c. Polygenic trait

d. Maternal trait

Answer: (b)

Question 15:

It is said that Mendel proposed that the factor controlling any character is discrete and independent. This proposition was based on the:

a. Results of generation of a cross.

b. Observations that the offspring of a cross made between the plants having two contrasting characters shows only one character without any blending.

c. Self-pollination of offspring’s

d. Cross pollination of parental generations

Answer: (b)

Question 16:

Two genes ‘A’ and ‘B’ are linked. In a dihybrid cross involving these two genes, the heterozygote is crossed with homozygous recessive parental type . What would be the ratio of offspring in the next generation?





Answer: (a)

Question 17:

In the generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are:

a. Phenotypes - 4; genotypes - 16

b. Phenotypes - 9; genotypes - 4

c. Phenotypes - 4; genotypes - 8

d. Phenotypes - 4; genotypes - 9

Answer: (d)

Question 18:

Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood group respectively. What would be the genotype of both mother and father?

a. Mother is homozygous for ‘A’ blood group and father is heterozygous for ‘B’

b. Mother is heterozygous for ‘A’ blood group and father is homozygous for ‘B’

c. Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively

d. Both mother and father are homozygous for ‘A’ and ‘B’ blood group, respectively

Answer: (c)