Which of the following is the basic unit of heredity?
Answer: A
A gene is the fundamental unit of heredity that carries information for a specific trait. It consists of a segment of DNA coding for a protein or RNA.
Q.2Easy
What is the chromosome number in a normal human somatic cell?
Answer: B
Humans have 46 chromosomes (23 pairs) in somatic cells - 22 pairs of autosomes and 1 pair of sex chromosomes (XX or XY).
Q.3Easy
Which law states that traits are inherited through discrete units?
Answer: A
Mendel's Law of Segregation states that hereditary traits are controlled by discrete units (genes) that separate during gamete formation.
Q.4Easy
In a monohybrid cross between two heterozygous individuals (Aa × Aa), what is the probability of homozygous recessive offspring?
Answer: A
Monohybrid cross Aa × Aa produces genotypic ratio 1 AA : 2 Aa : 1 aa. Probability of aa (homozygous recessive) = 41 or 25%.
Q.5Easy
Which of the following best describes alleles?
Answer: A
Alleles are alternative forms of a gene that occupy the same locus on homologous chromosomes and control different variations of the same trait.
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Q.6Easy
A cross between a homozygous dominant (AA) and homozygous recessive (aa) individual produces offspring that are all:
Answer: B
AA × aa produces all Aa offspring (test cross principle). All offspring are heterozygous with dominant phenotype.
Q.7Easy
Gene mutation is defined as:
Answer: B
Mutation is a permanent change in the DNA sequence that can occur spontaneously or be induced. It is the source of genetic variation.
Q.8Easy
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.9Easy
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.10Easy
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.11Easy
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.12Easy
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.13Easy
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.14Easy
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).
Q.15Easy
Which of the following statements about mutations is INCORRECT?
Answer: B
Most mutations are either neutral or harmful; only rarely are they beneficial. This is a key principle in evolutionary biology.
Q.16Easy
A cross between two pea plants produces offspring in the ratio 1:2:1 for a particular trait. This ratio suggests:
Answer: A
1:2:1 ratio indicates Aa × Aa, where offspring are 1 AA : 2 Aa : 1 aa. This is the typical F2 ratio for a monohybrid cross.
Q.17Easy
In human genetics, the ABO blood group is determined by multiple alleles. A person with blood type AB has which genotype?
Answer: C
Type AB blood group is codominant, expressed as IAIB, where both IA and IB alleles are expressed equally.
Q.18Easy
Which evolutionary evidence involves structural similarities between embryos of different species during early development?
Answer: C
Embryological similarities, such as gill slits in vertebrate embryos, demonstrate common evolutionary ancestry among different species.
Q.19Easy
Which of the following best describes the Hardy-Weinberg equilibrium principle?
Answer: A
Hardy-Weinberg equilibrium states that allele frequencies remain constant when no evolutionary forces (mutation, selection, migration, genetic drift) act on a population.
Q.20Easy
In a dihybrid cross between AaBb × AaBb, what is the probability of obtaining aabb genotype?
Answer: A
For AaBb × AaBb, probability of aa = 41 and bb = 41. Combined probability = 41 × 41 = 161.
