Free Inheritance MCQs with Answers

• A. Homozygous recessive alleles
• B. Homozygous dominant alleles
• C. Heterozygous dominant alleles
• D. Heterozygous recessive alleles

Explanation: Dwarf plants appear only when both alleles are recessive (tt), i.e homozygous recessive.

• A. 1:3
• B. 3:9
• C. 3:1
• D. 9:3

Explanation: The phenotypic ratio in a monohybrid cross is 3 dominant : 1 recessive, so recessive to dominant = 1:3.

• A. Monohybrid cross
• B. Test cross
• C. Dihybrid cross
• D. None of these

Explanation: A test cross involves crossing with a homozygous recessive to reveal the unknown genotype of another plant.

• A. 3:1
• B. 1:3
• C. 1:2:1
• D. 4:0

Explanation: Crossing Tt × Tt yields genotypes TT, Tt, Tt, tt, giving a ratio of 1:2:1.

• A. 3/16 tall, round: 3/16 dwarf, wrinkled
• B. 9/16 tall, round : 1/16 dwarf, round
• C. 9/16 tall, wrinkled: 3/16 dwarf, round
• D. 3/16 tall, wrinkled; 3/16 round dwarf

Explanation: In a dihybrid cross, the phenotypic ratio is 9:3:3:1, which includes 3/16 tall wrinkled and 3/16 round dwarf.

• A. Synapse
• B. Crossing over
• C. Independent assortment
• D. Both b and c

Explanation: Mendel studied traits on different chromosomes, where crossing over and independent assortment prevented linkage.

• A. Round and yellow seeds
• B. Wrinkled and yellow seeds
• C. Round and green seeds
• D. Wrinkled and green seeds

Explanation: All F₁ plants are RrYy, expressing the dominant traits → round and yellow seeds..

• A. 1/16
• B. 3/16
• C. 2/16
• D. 4/16

Explanation: In a dihybrid cross, only 1/16 offspring are double recessive (rryy), giving wrinkled green seeds.

• A. 2
• B. 1
• C. 3
• D. 4

Explanation: Only RRyy plants are homozygous round with green seeds, appearing in 1/16 of progeny.

• A. 50% purple , 50% white
• B. All white
• C. 30% white , 70% purple
• D. All purple

Explanation: Purple is dominant over white, so F₁ offspring (Pp) all show purple flowers.

• A. Different alleles expressed in heterozygous condition
• B. Complete dominance of one allele
• C. Phenotype of heterozygote is intermediate
• D. Gene mutation produces alleles

Explanation: In incomplete dominance, heterozygotes show a blended phenotype (intermediate between homozygotes).

• A. Genetic drift
• B. Natural selection
• C. Mutation
• D. Non-random mating

Explanation: Mutations in DNA create new alleles, introducing genetic variation in populations.

• A. Multiple allelism
• B. Co-dominance
• C. Complete dominance
• D. Gene linkage

Explanation: ABO blood group is controlled by three alleles (IA, IB , i) is an example of multiple allelism.

• A. Have one allele
• B. Have no alleles
• C. Have two of them
• D. None of these

Explanation: Diploid organisms inherit two alleles for each gene (one from each parent), even if more alleles exist in the population.

• A. Complete dominance
• B. Mutation
• C. Sex linkage
• D. Gene linkage

Explanation: The ABO system arose from mutations in the "I" gene, producing IA , IB , and i alleles.

• A. Option A
• B. Option A and B
• C. Option C
• D. Option D

Explanation: Blood group A can be IᴬIᴬ (homozygous) or Iᴬi (heterozygous), since A is dominant over O.

• A. Blood group A
• B. Blood group AB
• C. Blood group B
• D. Blood group O

Explanation: Presence of B antigen on RBCs with anti-A antibodies in plasma defines group B.

• A. A and B groups only
• B. A and O groups only
• C. AB only
• D. All four groups

Explanation: Mother A can be IᴬIᴬ ,or Iᴬi; father is O can be ii. Offspring genotypes are Iᴬi (type A) or ii (type O).

• A. Six
• B. Four
• C. Three
• D. Five

Explanation: IA , IB and i give six genotypes but phenotypes collapse to A, B, AB, O - so 4 observable blood types (IA and IB are codominant; i is…

• A. AB
• B. B
• C. A
• D. O

Explanation: Father O = ii can only pass i. AB requires one IA and one IB allele that is impossible if one parent contributes only i.