A cross between a homozygous tall plant (TT) and homozygous dwarf plant (tt) produces F1 generation. When F1 is self-pollinated, the ratio of tall to dwarf plants in F2 will be:
Answer: A
F1 (Tt) self-pollination gives 3 tall (TT, Tt, Tt) : 1 dwarf (tt) ratio following Mendelian monohybrid cross pattern.
Q.22Medium
In Drosophila, white eye color (w) is X-linked recessive. A white-eyed female (XwXw) is crossed with a red-eyed male (XW Y). What percentage of offspring will have white eyes?
Answer: B
Female XwXw × Male XWY produces: XWXw (red female), XwXw (white female), XWY (red male), XwY (white male). 50% of total offspring are white-eyed.
Q.23Medium
Which of the following represents a point mutation that does NOT change the amino acid sequence of a protein?
Answer: C
Silent mutations occur in the third position of codons (wobble base), changing the DNA sequence but not the amino acid due to codon degeneracy.
Q.24Easy
A man with blood group AB marries a woman with blood group O. Their children will have blood groups:
Answer: A
Man (IAIB) × Woman (ii) produces IAi (Group A) and IBi (Group B) offspring only. O group requires ii genotype.
Q.25Medium
According to Hardy-Weinberg equilibrium, if the frequency of allele 'A' is 0.6 and allele 'a' is 0.4 in a population, what will be the frequency of heterozygotes (Aa)?
Answer: C
Frequency of Aa = 2pq where p = 0.6 and q = 0.4; 2(0.6)(0.4) = 0.48
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Q.26Easy
Which of the following evolutionary evidences is based on the study of vestigial structures like human tailbone and wisdom teeth?
Answer: B
Vestigial structures are anatomical remnants that indicate common ancestry with other organisms, supporting comparative morphology evidence.
Q.27Easy
In pea plants, yellow seed (Y) is dominant over green (y). If a cross produces 75% yellow and 25% green seeds, what was the genotype of the parents?
Answer: B
3:1 ratio (75% yellow : 25% green) is characteristic of monohybrid cross between two heterozygotes (Yy × Yy).
Q.28Medium
A homozygous round seed pea plant (RR) is crossed with homozygous wrinkled seed plant (rr). The F1 seeds are planted and self-pollinated. In the F2 generation, what fraction of round seed plants will be homozygous?
Answer: A
F1 is Rr (all round). F2: 1 RR : 2 Rr : 1 rr. Among round seeds (3 total), only 1 is homozygous RR, so 31.
Q.29Medium
Which mechanism of evolution is responsible for random changes in allele frequencies in small populations?
Answer: C
Genetic drift causes random, unpredictable changes in allele frequencies, particularly significant in small isolated populations.
Q.30Easy
A couple plans to have children. The man is a carrier for cystic fibrosis (Aa) and the woman is homozygous normal (AA). What is the probability their child will have cystic fibrosis?
Answer: A
Cross AA × Aa produces AA and Aa offspring only. Cystic fibrosis requires aa genotype, so probability is 0%.
Q.31Medium
The peppered moth experiment by Kettlewell during industrial revolution demonstrated which evolutionary concept?
Answer: B
Dark moths increased in polluted areas not by developing dark color, but because pre-existing dark variants had survival advantage.
Q.32Hard
Which of the following mutations would most likely be lethal?
Answer: C
Loss of an entire chromosome causes imbalance in gene dosage affecting multiple essential genes, making it almost always lethal.
Q.33Medium
A red-eyed Drosophila female (XW) is crossed with a white-eyed male (XwY). What will be the phenotypes of F1 offspring?
The concept of 'survival of the fittest' in evolution primarily refers to:
Answer: B
'Fitness' in evolutionary context means reproductive success—leaving maximum viable offspring, not physical strength.
Q.35Medium
A testcross of a tall plant with unknown genotype produces 50% tall and 50% dwarf offspring. The tall parent's genotype must be:
Answer: B
1:1 ratio indicates heterozygous tall plant (Tt) crossed with homozygous recessive dwarf (tt).
Q.36Easy
Homologous structures in different species indicate:
Answer: B
Homologous structures are similar due to common ancestry with modification over time—classical evidence for divergent evolution.
Q.37Medium
In ABO blood group genetics, if both parents have AB blood group, what blood groups are IMPOSSIBLE in their children?
Answer: A
AB parents (IAIB × IAIB) produce IAIA, IAIB, and IBIB only. O group (ii) requires two recessive alleles, which neither parent possesses.
Q.38Hard
Which of the following best explains why antibiotic-resistant bacteria increase in a population after antibiotic exposure?
Answer: C
Pre-existing resistant bacteria survive antibiotic exposure while susceptible ones die, increasing resistant population frequency—natural selection.
Q.39Hard
If a woman with normal vision (but carrier for color blindness) has children with a color-blind man, what percentage of their daughters are expected to have normal vision?
Answer: B
Carrier mother (XBXb) × Color-blind father (XbY) produces: XBXb (carrier daughter), XbXb (color-blind daughter), XBY (normal son), XbY (color-blind son). 50% of daughters (1 out of 2) have normal vision.
Q.40Easy
In Drosophila, the gene for white eyes (w) is X-linked recessive. A white-eyed female is crossed with a red-eyed male. What will be the phenotype of F1 females?
Answer: A
White-eyed female (XwXw) × red-eyed male (XWY). F1 females receive Xw from mother and XW from father, making them XWXw (red-eyed carriers).
