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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- A. maize
- B. the garden pea
- C. Drosophila
- D. the snapdragon
Explanation: Pisum sativum was an ideal choice because it has clearly contrasting characters, is normally self pollinating so pure lines are easy to…
Correct answer: the garden pea- A. independent assortment
- B. dominance
- C. segregation
- D. linkage
Explanation: The law of segregation follows from the separation of homologous chromosomes in anaphase I of meiosis, so a heterozygote produces two…
Correct answer: segregation- A. 1:1
- B. 9:3:3:1
- C. 1:2:1
- D. 3:1
Explanation: Crossing two heterozygotes gives one homozygous dominant, two heterozygotes and one homozygous recessive, and since the first three all…
Correct answer: 3:1- A. 9:3:3:1
- B. 3:1
- C. 1:1:1:1
- D. 12:3:1
Explanation: Each gene independently gives a three to one ratio, so combining two of them multiplies out to nine both dominant, three of each single…
Correct answer: 9:3:3:1- A. another tall plant of unknown genotype
- B. a dwarf plant
- C. a known heterozygous tall plant
- D. itself only
Explanation: A test cross uses the homozygous recessive parent, here the dwarf, because such a parent contributes only recessive alleles and so the…
Correct answer: a dwarf plant- A. 1:2:1
- B. 3:1
- C. 9:3:3:1
- D. 1:1
Explanation: Of four F2 offspring one is homozygous dominant, two are heterozygous and one is homozygous recessive.
Correct answer: 1:2:1- A. codominance
- B. incomplete dominance
- C. epistasis
- D. multiple alleles
Explanation: In incomplete dominance the heterozygote shows a blend, because one dose of the functional allele makes too little pigment for full…
Correct answer: incomplete dominance- A. incomplete dominance
- B. sex linkage
- C. codominance
- D. epistasis
Explanation: A person of group AB makes both the A antigen and the B antigen on the red cell surface, so neither allele is diluted or masked and both…
Correct answer: codominance- A. a single pair of alleles at one locus
- B. two separate genes on two chromosomes
- C. sex linked inheritance
- D. multiple alleles, three of which exist at one locus
Explanation: The gene has three alleles in the population, I A, I B and i, though any one individual carries only two of them, and this is the…
Correct answer: multiple alleles, three of which exist at one locus- A. close together on the same chromosome
- B. on different chromosomes or far apart on the same one
- C. both recessive
- D. both on the X chromosome
Explanation: Independent assortment comes from the random orientation of different homologous pairs at metaphase I, so it requires the genes to be on…
Correct answer: on different chromosomes or far apart on the same one- A. allelic
- B. linked
- C. homologous
- D. codominant
Explanation: All the genes on one chromosome form a linkage group, and the number of linkage groups in a species equals its haploid chromosome number.
Correct answer: linked- A. metaphase I
- B. anaphase I
- C. prophase I
- D. telophase II
Explanation: During the pachytene stage of prophase I the homologues are paired as bivalents, and non sister chromatids exchange equal segments at…
Correct answer: prophase I- A. 10 map units
- B. 1 map unit
- C. 90 map units
- D. 100 map units
Explanation: One map unit, or centimorgan, is defined as a recombination frequency of one per cent, so ten per cent recombinants means ten map units…
Correct answer: 10 map units- A. keeps linkage groups permanently intact
- B. halves the chromosome number of the gametes
- C. ensures that all gametes are genetically identical
- D. produces new combinations of alleles on the same chromosome
Explanation: Exchange between non sister chromatids creates chromosomes carrying combinations of alleles that neither parent had, and this…
Correct answer: produces new combinations of alleles on the same chromosome- A. a man has only one X chromosome, so a single recessive allele is expressed
- B. the gene lies on the Y chromosome
- C. the allele is dominant in men and recessive in women
- D. women lose the allele during meiosis
Explanation: The gene is on the X chromosome and a man is hemizygous, so there is no second copy that could mask a defective allele.
Correct answer: a man has only one X chromosome, so a single recessive allele is expressed- A. 0
- B. one in four
- C. one in two
- D. certain
Explanation: A son takes his single X from his mother, and half of her X chromosomes carry the defective allele, so half the sons are colour blind.
Correct answer: one in two- A. clotting factor VIII
- B. vitamin K
- C. platelets
- D. haemoglobin
Explanation: The X linked recessive gene codes for antihaemophilic factor VIII, and without it the clotting cascade stalls, so even a small injury…
Correct answer: clotting factor VIII- A. her mother alone is colour blind
- B. her father alone is colour blind
- C. her father is colour blind and her mother is at least a carrier
- D. neither parent carries the allele
Explanation: A girl has two X chromosomes and needs the recessive allele on both, one from each parent.
Correct answer: her father is colour blind and her mother is at least a carrier- A. the ovum, which may carry either an X or a Y chromosome
- B. the hormones of the mother during pregnancy
- C. the total number of chromosomes in the zygote
- D. the sperm, which carries either an X or a Y chromosome
Explanation: The mother is XX and so every ovum carries an X, while the father is XY and produces X bearing and Y bearing sperm in equal numbers, so it…
Correct answer: the sperm, which carries either an X or a Y chromosome20. In X linked recessive inheritance, the criss cross pattern means that a trait typically passes from
- A. father to son directly
- B. mother to daughter only
- C. father to every one of his sons
- D. an affected man to his grandsons through his carrier daughters
Explanation: An affected father gives his X, and therefore the allele, to all of his daughters, who become carriers, and half of their sons then…
Correct answer: an affected man to his grandsons through his carrier daughtersInheritance MCQs: common questions
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