Free Inheritance MCQs with Answers
1,238 Inheritance MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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181. The condition in which both alleles of a gene are expressed equally in heterozygotes is called:
- A. Incomplete dominance
- B. Codominance
- C. Epistasis
- D. Polygenic inheritance
Explanation: In codominance, both alleles express fully and simultaneously Example: AB blood group (I I where both A and B antigens appear).
Correct answer: Codominance- A. ABO blood group
- B. Snapdragon flower color
- C. Human height
- D. Sickle cell anemia
Explanation: In snapdragon, red × white → pink F1. Here heterozygotes show intermediate phenotype, a hallmark of incomplete dominance.
Correct answer: Snapdragon flower color- A. Only sons
- B. Only daughters
- C. Both sons and daughters
- D. Neither sons nor daughters
Explanation: Carrier female (XHXh) can pass Xh to sons (XhY = hemophiliac) or daughters (XHXH = carrier). Thus, both can inherit the allele.
Correct answer: Both sons and daughters- A. Multiple alleles
- B. Linked genes
- C. Independent genes
- D. Recessive alleles
Explanation: Genes on the same chromosome that are inherited together (not assorted independently) are linked genes.
Correct answer: Linked genes- A. They are tightly linked
- B. They are on different chromosomes
- C. They are very close on the same chromosome
- D. Crossing over never occurs
Explanation: A recombination frequency of 50% indicates genes assort independently, i.e, they behave as if on different chromosomes.
Correct answer: They are on different chromosomes- A. Down syndrome
- B. Klinefelter's syndrome
- C. Turner's syndrome
- D. Super male syndrome
Explanation: XYY males (47 chromosomes) are taller, may have mild learning difficulties, but usually fertile.
Correct answer: Super male syndrome- A. Animals
- B. Plants
- C. Both equally
- D. Viruses
Explanation: Polyploidy (extra sets of chromosomes) is rare in animals but common in plants, where it often leads to larger size and hybrid vigor (e.g…
Correct answer: Plants- A. 25%
- B. 50%
- C. 75%
- D. 100%
Explanation: The ability to taste the substance is dominant (T) and the inability to taste is recessive (t).
Correct answer: 25%- A. Tongue rolling
- B. Baldness
- C. Haemophilia
- D. Skin color
Explanation: Hemophilia is X-linked recessive, affecting mostly males. Tongue rolling and skin color are autosomal traits, while baldness is…
Correct answer: Haemophilia- A. 1 Tall : 1 Dwarf
- B. 3 Tall : 1 Dwarf
- C. All Tall
- D. All Dwarf
Explanation: Cross: Tt × tt → Tt (tall), tt (dwarf). Ratio = 1:1.
Correct answer: 1 Tall : 1 Dwarf- A. Genotype
- B. Phenotype
- C. Allele
- D. Genomic imprinting
Explanation: Phenotype is the observable physical or physiological traits of an organism, determined by its genes and environment.
Correct answer: Phenotype- A. Particulate inheritance
- B. Dominance
- C. Segregation
- D. Independent assortment
Explanation: The law of segregation states that each individual that is a diploid has a pair of alleles (copy) for a particular trait.
Correct answer: Segregation- A. Homozygous, heterozygous
- B. Homozygous, recessive
- C. Dominant, recessive
- D. Dominant, incomplete
Explanation: The masked allele is called recessive and the allele that expresses itself is called the dominant
Correct answer: Dominant, recessive- A. 1 tall: 1 dwarf
- B. 3 tall: 1 dwarf
- C. 1 tall : 2 medium : 1 dwarf
- D. All tall
Explanation: If a parent is heterozygous dominant then the genotype will be Tt and Tt.
Correct answer: 3 tall: 1 dwarf- A. 0%
- B. 25%
- C. 75%
- D. 100%
Explanation: The probability that their next child will be albino is 25% (B). This is because both parents are carriers of the albinism gene, so there…
Correct answer: 25%- A. 1/2x 1/2 = 1/4
- B. 1/3 x 1/2 = 1/6
- C. 2/3 x 1/4 = 1/6
- D. 2/3 x 1/2 = 1/3
Explanation: Cystic fibrosis is an autosomal recessive disorder. If Kathy is a carrier, there is a 50% chance she will pass on the CF allele to her…
Correct answer: 2/3 x 1/2 = 1/3- A. An autosomal dominant
- B. An autosomal recessive
- C. Either dominant or recessive
- D. Sex-linked
Explanation: Dominant mutations are expressed when only one copy of that mutation is present.
Correct answer: An autosomal dominant- A. 1:1:1:1 ratio
- B. 9:3:3:1 ratio
- C. All dominant for both traits
- D. All recessive for both traits
Explanation: Both the product rule and the Punnett Square approaches showed that a 9:3:3:1 phenotypic ratio is expected among the progeny of a dihybrid…
Correct answer: 9:3:3:1 ratio- A. Particulate inheritance
- B. Dominance
- C. Segregation
- D. Independent assortment
Explanation: The Principle of Independent Assortment describes how different genes independently separate from one another when reproductive cells…
Correct answer: Independent assortment200. Which of the following incorrectly identifies the mode of inheritance for the given genetic disease?
- A. Distal symphalangism-dominant
- B. Cystic fibrosis-recessive
- C. Albinism-recessive
- D. Sickle cell-dominant
Explanation: Sickle cell disease is a hereditary disease seen most often among people of African ancestry.
Correct answer: Sickle cell-dominant