MDCAT Biology Inheritance Test Online MCQs

MDCAT Biology Inheritance Test

MDCAT Biology preparation with this focused online MCQ test on Inheritance. Covering topics like Mendel’s laws, gene linkage, crossing over, and sex-linked traits, this quiz is based on the updated MDCAT 2025 syllabus to help you master the principles of heredity.

MDCAT 2025 Inheritance Online Test

Inheritance MCQS Online Question with Answer

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1. What is the expected genotypic ratio of a monohybrid cross between two heterozygotes?

9:3:3:1

1:1

1:2:1

3:1

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2. What is gene mapping based on?

Frequency of crossing over

Physical size of chromosomes

Shape of DNA

Location of traits

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3. Which process leads to genetic recombination?

Mitosis

Replication

Crossing over

Translation

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4. In hemophilia, a female must inherit:

One defective X

One defective Y

One defective autosome

Two defective X chromosomes

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5. A recessive allele is expressed only when:

It is present on both homologous chromosomes

It is present on a Y chromosome

It is dominant over another allele

It is on a heterozygous genotype

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6. Gene linkage occurs when:

Genes are located close together on the same chromosome

Genes code for the same protein

Genes are silenced

Genes are located on different chromosomes

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7. In a Punnett square of an XʰX × XY cross, what is the chance of a daughter being a carrier?

25%

50%

100%

0%

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8. What is the result of crossing TT (tall) with tt (short) pea plants?

50% tall, 50% short

All short

All medium

All tall

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9. A hemophilic male and a carrier female have how many chances of passing on the disease?

50%

75%

25%

100%

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10. In X-linked inheritance, who can be carriers of the trait?

Only females

Neither

Only males

Both males and females

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11. What does the Law of Independent Assortment explain?

Dominant traits hide recessive ones

Each pair of alleles segregates independently during gamete formation

Mutations occur randomly

Alleles always segregate together

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12. What does heterozygous mean?

Having two identical alleles

Having one allele

Having different alleles

Having a dominant trait only

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13. A female with normal genes for clotting marries a hemophilic man. What is the chance their son will have hemophilia?

100%

0%

50%

25%

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14. In Mendel’s experiments, which trait was dominant?

White flower

Short stem

Wrinkled seeds

Tall stem

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15. What is the significance of independent assortment?

It ensures mutation

It maintains genetic stability

It increases genetic variation

It increases the number of cells

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16. Which scientist is known as the father of genetics?

Mendel

Watson

Darwin

Lamarck

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17. What process can separate linked genes?

Crossing over

Translation

Replication

Transcription

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18. Which phase of meiosis does crossing over occur?

Prophase I

Metaphase I

Telophase I

Anaphase II

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19. Which of the following terms best describes the physical appearance of an organism?

Genotype

Allele

Phenotype

Karyotype

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20. Which term refers to different forms of a gene?

Alleles

Traits

Nucleotides

Chromatids

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21. Which of the following would have a 100% chance of passing on an X-linked recessive trait to daughters?

Carrier mother

Carrier father

Affected father

Normal mother

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22. Why are X-linked recessive traits more common in males?

Males have only one X chromosome

Y chromosome protects them

Males have two X chromosomes

Males are more prone to mutations

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23. What is the effect of crossing over on linked genes?

Has no effect

May separate them, increasing variation

Ensures they always remain linked

Prevents their expression

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24. Why can’t fathers pass X-linked traits to sons?

Sons don’t have X chromosomes

Fathers don’t carry defective genes

Sons reject X chromosomes

Fathers only pass the Y chromosome to sons

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25. Which term describes genes located on the same chromosome and inherited together?

Codominant genes

Alleles

Recessive genes

Linked genes

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26. What is the probability that a carrier mother and a normal father will have a son with hemophilia?

100%

50%

0%

25%

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27. Which of the following best describes Mendel's Law of Segregation?

Traits are inherited in pairs

Alleles for a trait separate during gamete formation

Genes always blend in offspring

Dominant traits are always expressed

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28. How many alleles does a diploid organism have for each gene?

One

Three

Two

Four

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29. How many types of gametes can be produced by a heterozygous dihybrid individual (TtRr)?

8

2

4

1

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30. The units of inheritance are:

Genes

Chromosomes

Ribosomes

Proteins

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31. In which sex is hemophilia most commonly expressed?

Both equally

Females

Only children

Males

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32. A male inherits his X chromosome from:

His mother

His father

Both parents

Only from autosomes

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33. If two carriers of a recessive disorder marry, what is the chance their child will be affected?

100%

50%

25%

0%

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34. Which of the following crosses would show Mendel’s Law of Independent Assortment?

Tt × tt

TT × Tt

TtRr × TtRr

TT × tt

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35. Hemophilia primarily affects:

Blood clotting

Digestive system

Nerve function

Muscle strength

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36. A carrier female for hemophilia would have the genotype:

XY

XʰX

XʰXʰ

XX

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37. Which of the following diseases is caused by an X-linked recessive gene?

Cancer

Sickle-cell anemia

Hemophilia

Diabetes

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38. Which of the following is a result of gene linkage?

Inherited traits appear together

Random recombination

Traits assort independently

Greater genetic variation

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39. Sex-linked genes are mostly located on:

Autosomes

Mitochondrial DNA

Y chromosome

X chromosome

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40. What is the condition in which an individual has two identical alleles for a trait?

Hybrid

Homozygous

Heterozygous

Diploid

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41. Which of the following is an example of a dihybrid trait?

Blood type in humans

Height and seed shape in pea plants

Height in pea plants

Flower color in pea plants

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42. Which of the following violates the law of independent assortment?

Codominance

Crossing over

Gene linkage

Mutation

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43. Which of the following is a test cross?

Tt × tt

TT × Tt

Tt × Tt

TT × TT

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44. If T is dominant for tall and t for dwarf, what is the phenotype of Tt?

Tall

Dwarf

Medium height

Recessive

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45. What does a test cross help determine?

The presence of recessive traits only

The blood group

The number of chromosomes

Whether an individual is heterozygous or homozygous dominant

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46. What is the purpose of a Punnett square?

To study chromosomes under a microscope

To determine the age of a gene

To predict the probability of genetic traits

To identify dominant alleles

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47. In Mendel's dihybrid cross, what phenotypic ratio is expected in the F2 generation?

1:1

3:1

9:3:3:1

1:2:1

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48. Which of the following best defines crossing over?

Exchange of genetic material between sister chromatids

Exchange of segments between non-sister chromatids of homologous chromosomes

Random mutation of DNA

Segregation of alleles during mitosis

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