Inheritance

Inheritance MDCAT MCQs with answers

104 past paper MCQs from Biology unit 10, Inheritance, across 3 topics. They are arranged topic by topic; bigger topics show a sample here and link to their full set and to study notes. Tap “Show answer” for the correct option and a short solution.

Practise as a quiz

Mendel's Laws of Inheritance

1.A test cross is made to check the genotype of a trait. Which of the following crosses is a test cross? (MDCAT 2022)

  1. unknown $\times$ Tt
  2. unknown $\times$ tt
  3. unknown $\times$ AB
  4. unknown $\times$ TT
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Correct answer: (b) unknown $\times$ tt

The homozygous recessive parent contributes no dominant allele, so the offspring reveal what the unknown carried.

2.A test cross is made to check the genotype of a trait. Which of the following crosses is a test cross? (MDCAT 2023)

  1. unknown $\times$ Tt
  2. unknown $\times$ tt
  3. unknown $\times$ AB
  4. unknown $\times$ TT
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Correct answer: (b) unknown $\times$ tt

Crossing with the homozygous recessive lets the unknown's alleles show in the offspring.

3.According to Mendel's law of segregation, one individual out of four in the $F_2$ generation had a phenotype that failed to express in which generation? (MDCAT 2023)

  1. $F_1$
  2. $F_3$
  3. $F_2$
  4. $P_1$
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Correct answer: (a) $F_1$

The recessive phenotype is hidden in the $F_1$ and reappears in a quarter of the $F_2$.

All 48 Mendel's Laws of Inheritance MCQs → Mendel's Laws of Inheritance notes →

X-linked Inheritance

4.To study sex linkage in Drosophila, Morgan mated white eyed males with wild type red eyed females. What will be the phenotype of the offspring? (MDCAT 2022)

  1. all red eyed males and females
  2. red eyed females and white eyed males
  3. white eyed females and red eyed males
  4. all white eyed females and males
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Correct answer: (a) all red eyed males and females

Every daughter gets a red allele from her mother and every son gets his single X from her too, so the whole $F_1$ is red eyed.

5.The mode of inheritance in humans can be traced through: (MDCAT 2022)

  1. experimental mating
  2. chi square charts
  3. pedigree analysis
  4. probability analysis
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Correct answer: (c) pedigree analysis

Human families cannot be bred to order, so the record of a trait through the generations is what is studied.

6.Which one of the following is an X-linked dominant disorder? (MDCAT 2023)

  1. haemophilia
  2. colour blindness
  3. hypophosphataemic rickets
  4. hypertrichosis
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Correct answer: (c) hypophosphataemic rickets

Hypophosphataemic rickets is carried on the X chromosome and shows in the heterozygote; haemophilia and colour blindness are X-linked recessive.

All 30 X-linked Inheritance MCQs → X-linked Inheritance notes →

Gene Linkage and Crossing Over

7.The 9.3.3.1 ratio of law of Independent assortment can be affected by (UHS MDCAT 2025)

  1. Genetic drift
  2. Small population
  3. Gene linkage
  4. Gene duplication
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Correct answer: (c) Gene linkage

Genes on the same chromosome are inherited together, so linkage upsets the 9:3:3:1 ratio independent assortment predicts.

8.Best description of the process of crossing over during meiosis: (UHS MDCAT 2025)

  1. Duplication of chromosome
  2. Exchange of genes between non-sister chromatids
  3. Movement of chromosome to opposite poles
  4. Separation of sister chromatids
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Correct answer: (b) Exchange of genes between non-sister chromatids

Crossing over is the exchange of segments between non-sister chromatids of homologous chromosomes at prophase I.

9.Total number of linkage groups in a normal human is: (UHS MDCAT 2025)

  1. 02
  2. 23
  3. 46
  4. 92
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Correct answer: (b) 23

A linkage group is one chromosome of a haploid set, and the human haploid number is 23.

All 26 Gene Linkage and Crossing Over MCQs → Gene Linkage and Crossing Over notes →

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