NEET Biology Principles of Inheritance MCQs Set 01

Answer: (a) garden pea

Explanation:
1. Mendel used the garden pea, Pisum sativum, because it has clear contrasting traits, a short life cycle and is self-pollinating.
2. So the correct choice is option (a).

Teacher's Note:
1. Pisum sativum.
2. Seven pairs of contrasting traits.

Answer: (c) emasculation

Explanation:
1. Emasculation removes anthers before they shed pollen so that self-pollination is prevented and a controlled cross can be made.
2. So the correct choice is option (c).

Teacher's Note:
1. Emasculate the female parent.
2. Bagging follows emasculation.

Answer: (b) monohybrid cross

Explanation:
1. The 3:1 ratio of a monohybrid cross showed that the two factors of a pair separate and enter different gametes.
2. So the correct choice is option (b).

Teacher's Note:
1. Segregation: monohybrid.
2. Independent assortment: dihybrid.

Answer: (a) 1 AaBB : 1 aaBB

Explanation:
1. Aa x aa gives Aa and aa in equal numbers, and BB x BB gives only BB, so the ratio is 1 AaBB : 1 aaBB.
2. So the correct choice is option (a).

Teacher's Note:
1. Treat each gene separately.
2. Multiply the results.

Answer: (a) 1:1

Explanation:
1. Aa x aa gives 1 Aa : 1 aa, so both genotypes and phenotypes are 1:1.
2. So the correct choice is option (a).

Teacher's Note:
1. Test cross uses the recessive parent.
2. It reveals the genotype of the dominant individual.

Answer: (d) independent assortment

Explanation:
1. The 9:3:3:1 ratio shows that the two pairs of factors assort independently.
2. So the correct choice is option (d).

Teacher's Note:
1. Two genes on different chromosomes.
2. Four phenotypes in F2.

Answer: (d) 4 types in the ratio 1:1:1:1

Explanation:
1. AaBb forms AB, Ab, aB and ab in equal numbers.
2. So the correct choice is option (d).

Teacher's Note:
1. 9:3:3:1 is a phenotypic ratio.
2. Gametes: 2 to the power n types.

Answer: (c) 8

Explanation:
1. Each heterozygous gene gives two choices, so 2 x 2 x 2 = 8 kinds of gametes.
2. So the correct choice is option (c).

Teacher's Note:
1. 2 raised to number of heterozygous genes.
2. AaBbCc: 8.

Answer: (c) TtRr

Explanation:
1. A dihybrid is heterozygous for both genes, so TtRr.
2. So the correct choice is option (c).

Teacher's Note:
1. Dihybrid = two heterozygous gene pairs.
2. TTRr is a monohybrid.

Answer: (c) 1:2:2:1

Explanation:
1. In F2 of AaBb x AaBb, AABB is 1/16, AABb 2/16, aaBb 2/16 and aabb 1/16.
2. So the correct choice is option (c).

Teacher's Note:
1. Count the boxes in the 16-box Punnett square.
2. 1 : 2 : 2 : 1.

Answer: (a) 4

Explanation:
1. AA is fixed, and Bb and Cc each give two kinds: 2 x 2 = 4 types.
2. So the correct choice is option (a).

Teacher's Note:
1. Only heterozygous genes count.
2. AA gives one kind.

Answer: (d) 4/16

Explanation:
1. Aa is 1/2 and Bb is 1/2 in F2, so AaBb is 1/4 = 4/16.
2. So the correct choice is option (d).

Teacher's Note:
1. Multiply separate probabilities.
2. Aa = 1/2 in F2.

Answer: (d) all red

Explanation:
1. Red is dominant, so every F1 plant (all Rr) is red.
2. So the correct choice is option (d).

Teacher's Note:
1. F1 shows only the dominant trait.
2. No white in F1.

Answer: (d) homozygote

Explanation:
1. Identical alleles, such as TT or tt, make a homozygote.
2. So the correct choice is option (d).

Teacher's Note:
1. Homo = same.
2. Hetero = different.

Answer: (b) two homologous chromosomes

Explanation:
1. Alleles occupy the same locus on the two homologous chromosomes.
2. So the correct choice is option (b).

Teacher's Note:
1. Same locus, homologous chromosomes.
2. Different genes lie at different loci.

Answer: (b) 25

Explanation:
1. AaBb makes four kinds of gametes in equal numbers, so each, including ab, is 25 percent.
2. So the correct choice is option (b).

Teacher's Note:
1. Four equal types.
2. 100 / 4 = 25.

Answer: (a) gamete formation

Explanation:
1. The two alleles of a pair separate when gametes are formed, so each gamete gets only one.
2. So the correct choice is option (a).

Teacher's Note:
1. Segregation happens in meiosis.
2. Gametes are pure.

Answer: (b) 1:1:1:1

Explanation:
1. Tt x tt gives 1 Tt : 1 tt and rr x Rr gives 1 Rr : 1 rr, so the combined ratio is 1:1:1:1.
2. So the correct choice is option (b).

Teacher's Note:
1. Take each gene separately.
2. Multiply 1:1 by 1:1.

Answer: (d) recessive

Explanation:
1. A recessive allele is masked in heterozygotes by the dominant allele.
2. So the correct choice is option (d).

Teacher's Note:
1. Recessive shows only in homozygous state.
2. Dominant masks it.

Answer: (d) emasculation and bagging

Explanation:
1. He removed anthers (emasculation) and covered the flowers (bagging) to prevent unwanted pollination.
2. So the correct choice is option (d).

Teacher's Note:
1. Protoplast fusion is a modern technique.
2. Dusting pollen follows.

Answer: (c) 4

Explanation:
1. AaBb occurs as 1/2 x 1/2 = 1/4, i.e. 4 of 16 plants.
2. So the correct choice is option (c).

Teacher's Note:
1. 4 out of 16.
2. The 1:2:2:4 pattern for genotypes.

Answer: (c) heterozygous

Explanation:
1. Having two different alleles (Tt) makes a heterozygous plant.
2. So the correct choice is option (c).

Teacher's Note:
1. Dioecious and monoecious refer to sexes of flowers.
2. Hetero means different.

Answer: (a) 50%

Explanation:
1. Tt x tt gives 1 Tt : 1 tt, so half are dwarf.
2. So the correct choice is option (a).

Teacher's Note:
1. Test cross ratio 1:1.
2. Half tall, half dwarf.

Answer: (c) all plants are tall after self-pollination

Explanation:
1. A pure tall plant breeds true, so its selfed progeny are all tall. A hybrid gives dwarf plants too.
2. So the correct choice is option (c).

Teacher's Note:
1. Height alone cannot show genotype.
2. Test cross also works.