NEET Zoology — MCQ Practice Questions & Answers

Question 1

In pea plants, round seeds (R) are dominant over wrinkled seeds (r). If a plant with round seeds is crossed with a wrinkled seed plant and produces 50% round and 50% wrinkled seeds, the genotype of the round seed plant is:

Accepted Answer

Correct answer: B. Rr — The 1:1 ratio indicates a testcross result (Rr × rr). The round seed parent must be heterozygous (Rr) to produce wrinkled (rr) offspring.

Answer

A. RR

Answer

C. rr

Answer

D. Cannot be determined

Question 2

Which of the following represents the correct order of organization in genetic material?

Accepted Answer

Correct answer: C. Nucleotide → DNA → Gene → Chromosome — The correct hierarchical order is: Nucleotide (basic unit) → DNA (polymer of nucleotides) → Gene (segment of DNA) → Chromosome (condensed DNA with proteins).

Answer

A. Nucleotide → Gene → Chromosome → DNA

Answer

B. DNA → Nucleotide → Gene → Chromosome

Answer

D. Gene → DNA → Nucleotide → Chromosome

Question 3

According to the Hardy-Weinberg equation (p² + 2pq + q² = 1), what do p and q represent?

Accepted Answer

Correct answer: B. Allele frequencies — In Hardy-Weinberg equation, p and q represent frequencies of two alleles in a population. p² and q² are homozygous frequencies; 2pq is heterozygous frequency.

Answer

A. Genotype frequencies

Answer

C. Phenotype ratios

Answer

D. Mutation rates

Question 4

A population of 1000 individuals has 640 individuals with dominant phenotype and 360 with recessive phenotype. The frequency of recessive allele (q) is:

Accepted Answer

Correct answer: B. 0.60 — Recessive phenotype = 360/1000 = 0.36 = q². Therefore q = √0.36 = 0.60. This represents the frequency of recessive allele.

Answer

A. 0.36

Answer

C. 0.64

Answer

D. 0.40

Question 5

X-linked recessive inheritance patterns typically show:

Accepted Answer

Correct answer: A. More affected males than females — X-linked recessive traits show more affected males (XᵃY) than females because males need only one copy of recessive allele on their single X chromosome.

Answer

B. More affected females than males

Answer

C. Equal distribution between sexes

Answer

D. No sex-linked pattern

Question 6

Haemophilia A is inherited as:

Accepted Answer

Correct answer: C. X-linked recessive — Haemophilia A (clotting factor VIII deficiency) is X-linked recessive. Affected males (XᵃY) pass the allele to all daughters but no sons.

Answer

A. Autosomal dominant

Answer

B. Autosomal recessive

Answer

D. Y-linked

Question 7

A woman who is a carrier for color blindness (XᴮXᵇ) marries a normal man (XᴮY). What percentage of their sons will be color blind?

Accepted Answer

Correct answer: C. 50% — Color blindness is an X-linked recessive trait. To find the percentage of color-blind sons, we need to perform a cross between a carrier mother and a normal father, then analyze the male offspring. **Step 1: Identify the genotypes** Mother (carrier): X^B X^b — has one normal allele ( X^B ) and one color-blind allele ( X^b ) Father (normal): X^B Y — has the normal allele on his X chromosome **Step 2: Set up the Punnett square** Cross all maternal alleles with all paternal alleles: \begin{array}{c|cc} & X^B & Y \ \hline X^B & X^B X^B & X^B Y \ X^b & X^B X^b & X^b Y \ \end{array} **Step 3: Identify offspring genotypes and phenotypes** The four possible offspring are: - X^B X^B (daughter, normal) - X^B Y (son, normal) - X^B X^b (daughter, carrier) - X^b Y (son, color blind) **Step 4: Calculate percentage of color-blind sons** Among all sons (male offspring only): - X^B Y (normal): 1 out of 2 sons - X^b Y (color blind): 1 out of 2 sons 	ext{Percentage of color-blind sons} = \frac{1}{2} 	imes 100\% = 50\% **Answer: 50% of their sons will be color blind** **(Op

Answer

A. 0%

Answer

B. 25%

Answer

D. 75%

Question 8

Which type of mutation has no effect on the protein produced?

Accepted Answer

Correct answer: C. Silent mutation — Silent mutation occurs in the third position of a codon and does not change the amino acid due to degeneracy of genetic code. No phenotypic effect.

Answer

A. Missense mutation

Answer

B. Nonsense mutation

Answer

D. Frameshift mutation

NEET Zoology - MCQ Practice Questions