Principles of Inheritance and Variation — Page 6 | NEET Biology

Q51

Which one of the following cannot be explained on the basis of Mendel's Law of Dominance?

A The discrete unit controlling a particular character is called a factor

B Out of one pair of factors one is dominant and the other recessive

C Alleles do not show any blending and both characters recover in F2

D Factors occur in pairs

Correct Answer

Option C

Solution

(c) Recovery of parental types in F2 is explained by Law of Segregation, not Dominance.

Q52

Which one of the following conditions of the zygotic cell would lead to the birth of a normal human female child?

A Two X chromosomes

B Only one Y chromosome

C Only one X chromosome

D One X and one Y chromosome

Correct Answer

Option A

Solution

(a) XX = normal human female; XY = normal male.

Q53

Test cross in plants or Drosophila involves crossing

A between two genotypes with recessive trait

B between two F1 hybrids

C the F1 hybrid with a double recessive genotype

D between two genotypes with dominant trait

Correct Answer

Option C

Solution

(c) Test cross = F1 hybrid x homozygous recessive (aabb).

Q54

A person with unknown blood group needs emergency blood transfusion. The donor friend offers blood immediately. The donor's blood group was

A Type B

B Type AB

C Type O

D Type A

Correct Answer

Option C

Solution

(c) Type O is the universal donor blood group.

Q55

When two unrelated individuals are crossed, the F1 hybrid is often superior to both parents. This phenomenon is called

A heterosis

B transformation

C splicing

D metamorphosis

Correct Answer

Option A

Solution

(a) Heterosis (hybrid vigor): F1 hybrid outperforms both parents.

Q56

F2 generation in a Mendelian cross showed both genotypic and phenotypic ratios are same as 1:2:1. It represents

A Co-dominance

B Dihybrid cross

C Monohybrid cross with complete dominance

D Monohybrid cross with incomplete dominance

Correct Answer

Option D

Solution

(d) Incomplete dominance shows F2 genotypic = phenotypic ratio of 1:2:1.

Q57

A test cross is carried out to

A determine the genotype of a plant at F2

B predict whether two traits are linked

C assess the number of alleles of a gene

D determine whether two species will breed successfully

Correct Answer

Option A

Solution

(a) Test cross determines whether a dominant phenotype individual is homozygous or heterozygous.

Q58

A certain road accident patient needs immediate blood transfusion. His doctor friend offers blood immediately. What was the blood group of the donor?

A Blood group B

B Blood group AB

C Blood group O

D Blood group A

Correct Answer

Option C

Solution

(c) Blood group O is the universal donor.

Q59

Genetic variation in a population arises due to

A Mutations only

B Recombination only

C Mutations as well as recombination

D Reproductive isolation and selection

Correct Answer

Option C

Solution

(c) Both mutations and recombination contribute to genetic variation.

Q60

The production of gametes, formation of zygotes, F1 and F2 plants can be understood using

A Wenn diagram

B Pie diagram

C A pyramid diagram

D Punnett square

Correct Answer

Option D

Solution

(d) Punnett square (devised by Reginald Punnett) is used to predict genotype frequencies.