NEET Botany — MCQ Practice Questions & Answers

Question 1

In a dihybrid cross (AaBb × AaBb), what is the expected phenotypic ratio in F2?

Accepted Answer

Correct answer: B. 9:3:3:1 — The classical dihybrid cross ratio is 9:3:3:1, following Mendel's Law of Independent Assortment for two independently assorting genes.

Answer

A. 3:1

Answer

C. 1:2:2:4

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D. 1:1:1:1

Question 2

What is the term for genes located on the X chromosome?

Accepted Answer

Correct answer: B. Sex-linked genes — Sex-linked genes are located on sex chromosomes, particularly the X chromosome. X-linked traits show different inheritance patterns in males and females.

Answer

A. Autosomal genes

Answer

C. Cytoplasmic genes

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D. Lethal genes

Question 3

Color blindness in humans is an X-linked recessive trait. If a carrier female (XᶜX) marries a normal male (XᶜY), what percentage of their sons will be color blind?

Accepted Answer

Correct answer: C. 50% — Cross: XᶜX × XᶜY produces: XᶜXᶜ (normal daughter), XᶜX (carrier daughter), XᶜY (color blind son), XᶜY (normal son). 50% of sons are color blind.

Answer

A. 0%

Answer

B. 25%

Answer

D. 100%

Question 4

Which of the following is an example of incomplete dominance?

Accepted Answer

Correct answer: B. Red and white flowers producing pink flowers — Incomplete dominance occurs when the heterozygote shows an intermediate phenotype. Red × white flowers → pink flowers is a classic example.

Answer

A. ABO blood groups

Answer

C. Tall and short pea plants

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D. Black and white coat color in dogs

Question 5

What is codominance?

Accepted Answer

Correct answer: B. Both alleles are expressed equally in the heterozygote — In codominance, both alleles contribute equally to the phenotype. Example: AB blood group where both A and B antigens are expressed.

Answer

A. One allele completely masks the other

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C. The recessive allele is expressed

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D. Neither allele is expressed

Question 6

ABO blood group system in humans shows which type of inheritance?

Accepted Answer

Correct answer: C. Codominance — ABO blood groups show codominance. Alleles Iᴬ and Iᴮ are dominant over i but are codominant to each other, producing four blood types.

Answer

A. Simple dominance

Answer

B. Incomplete dominance

Answer

D. Sex-linked inheritance

Question 7

Which of the following best describes a mutation?

Accepted Answer

Correct answer: B. A sudden heritable change in DNA sequence — A mutation is any sudden, spontaneous change in the DNA sequence that can be inherited. It provides genetic variation for natural selection.

Answer

A. Segregation of alleles during meiosis

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C. Exchange of genetic material between homologous chromosomes

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D. Random distribution of chromosomes during cell division

Question 8

Linkage is the phenomenon where genes are inherited together because they are located on the same ______.

Accepted Answer

Correct answer: C. Chromosome — Linked genes are located close together on the same chromosome and tend to be inherited together, violating the Law of Independent Assortment.

Answer

A. Allele

Answer

B. Locus

Answer

D. Centromere

NEET Botany - MCQ Practice Questions