Principles of Inheritance and Variation — Page 7 | NEET Biology

Q61

Which of the following statements is not true of two genes that show 50% recombination frequency?

A The genes are tightly linked

B The genes show independent assortment

C If on same chromosome, they undergo more than one crossover per meiosis

D The genes may be on different chromosomes

Correct Answer

Option A

Solution

(a) 50% recombination indicates independent assortment, not tight linkage.

Q62

Which Mendelian idea is depicted by a cross in which the F1 generation resembles both parents?

A Law of dominance

B Inheritance of one gene

C Co-dominance

D Incomplete dominance

Correct Answer

Option C

Solution

(c) Co-dominance: F1 shows characteristics of both parents simultaneously.

Q63

A gene showing codominance has

A alleles tightly linked on the same chromosome

B alleles that are recessive to each other

C both alleles independently expressed in the heterozygote

D one allele dominant on the other

Correct Answer

Option C

Solution

(c) Codominance: both alleles are fully expressed in the heterozygote.

Q64

Multiple alleles are present

A at different loci on the same chromosome

B at the same locus of the chromosome

C on non-sister chromatids

D on different chromosomes

Correct Answer

Option B

Solution

(b) All alleles of a gene occupy the same locus on homologous chromosomes.

Q65

A man with blood group A marries a woman with blood group B. What are all the possible blood groups of their offspring?

A A,B and AB only

B A, B, AB and O

C O only

D A and B only

Correct Answer

Option B

Solution

(b) If man is IA i and woman is IB i, children can have A, B, AB, or O blood groups.

Q66

In his classic experiments on Pea plants, Mendel did not use

A Pod length

B Seed shape

C Flower position

D Seed colour

Correct Answer

Option A

Solution

(a) Pod length was not among Mendel's seven studied characters.

Q67

Alleles are

A true breeding homozygotes

B different molecular forms of a gene

C heterozygotes

D different phenotypes

Correct Answer

Option B

Solution

(b) Alleles are alternative molecular forms of the same gene at the same locus.

Q68

Which is the most common mechanism of genetic variation in sexually reproducing organisms?

A Chromosomal aberrations

B Genetic drift

C Recombination

D Transduction

Correct Answer

Option C

Solution

(c) Recombination (crossing over) is the most common source of genetic variation.

Q69

How many pairs of contrasting characters in pea plants were studied by Mendel?

A Six

B Eight

C Seven

D Five

Correct Answer

Option C

Solution

(c) Mendel studied seven pairs of contrasting characters in Pisum sativum.

Q70

In a test cross involving F1 dihybrid flies, more parental type offspring were produced than recombinant type. This indicates

A the two genes are on two different chromosomes

B chromosomes failed to separate during meiosis

C the two genes are linked on the same chromosome

D both characters are controlled by more than one gene

Correct Answer

Option C

Solution

(c) Excess parental types over recombinants indicates linkage.