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. Which of the following is a test cross?

Tt × Tt

TT × TT

TT × Tt

Tt × tt

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2. What does heterozygous mean?

Having one allele

Having different alleles

Having two identical alleles

Having a dominant trait only

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3. A recessive allele is expressed only when:

It is present on both homologous chromosomes

It is on a heterozygous genotype

It is present on a Y chromosome

It is dominant over another allele

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4. Gene linkage occurs when:

Genes code for the same protein

Genes are located close together on the same chromosome

Genes are silenced

Genes are located on different chromosomes

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5. What does the Law of Independent Assortment explain?

Alleles always segregate together

Dominant traits hide recessive ones

Mutations occur randomly

Each pair of alleles segregates independently during gamete formation

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

8

2

4

1

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

Fathers only pass the Y chromosome to sons

Sons don’t have X chromosomes

Fathers don’t carry defective genes

Sons reject X chromosomes

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

Lamarck

Watson

Mendel

Darwin

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

Blood type in humans

Height in pea plants

Flower color in pea plants

Height and seed shape in pea plants

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

Alleles

Codominant genes

Recessive genes

Linked genes

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

Neither

Only females

Only males

Both males and females

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

Alleles for a trait separate during gamete formation

Genes always blend in offspring

Dominant traits are always expressed

Traits are inherited in pairs

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14. Which process leads to genetic recombination?

Replication

Mitosis

Translation

Crossing over

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

50%

0%

100%

25%

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16. What does a test cross help determine?

The number of chromosomes

The presence of recessive traits only

The blood group

Whether an individual is heterozygous or homozygous dominant

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17. What is gene mapping based on?

Frequency of crossing over

Location of traits

Shape of DNA

Physical size of chromosomes

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18. In which sex is hemophilia most commonly expressed?

Both equally

Males

Females

Only children

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

Medium height

Recessive

Tall

Dwarf

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20. Sex-linked genes are mostly located on:

Y chromosome

X chromosome

Mitochondrial DNA

Autosomes

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

9:3:3:1

1:2:1

1:1

3:1

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

100%

25%

50%

0%

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23. Hemophilia primarily affects:

Blood clotting

Muscle strength

Digestive system

Nerve function

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24. In hemophilia, a female must inherit:

One defective autosome

Two defective X chromosomes

One defective Y

One defective X

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

All medium

All short

All tall

50% tall, 50% short

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

9:3:3:1

1:1

1:2:1

3:1

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27. What process can separate linked genes?

Transcription

Translation

Replication

Crossing over

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

Genotype

Phenotype

Karyotype

Allele

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

Random recombination

Traits assort independently

Inherited traits appear together

Greater genetic variation

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

50%

0%

25%

100%

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

Three

One

Four

Two

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

Heterozygous

Diploid

Hybrid

Homozygous

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

Sickle-cell anemia

Cancer

Hemophilia

Diabetes

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34. Which phase of meiosis does crossing over occur?

Metaphase I

Telophase I

Prophase I

Anaphase II

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

Gene linkage

Codominance

Mutation

Crossing over

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36. Which of the following best defines crossing over?

Segregation of alleles during mitosis

Random mutation of DNA

Exchange of genetic material between sister chromatids

Exchange of segments between non-sister chromatids of homologous chromosomes

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

Short stem

White flower

Tall stem

Wrinkled seeds

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

Carrier mother

Normal mother

Carrier father

Affected father

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

Traits

Chromatids

Nucleotides

Alleles

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40. What is the purpose of a Punnett square?

To identify dominant alleles

To determine the age of a gene

To predict the probability of genetic traits

To study chromosomes under a microscope

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41. A male inherits his X chromosome from:

His father

His mother

Both parents

Only from autosomes

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

XY

XʰX

XX

XʰXʰ

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

75%

50%

25%

100%

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

Males are more prone to mutations

Y chromosome protects them

Males have only one X chromosome

Males have two X chromosomes

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

Has no effect

Ensures they always remain linked

Prevents their expression

May separate them, increasing variation

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47. The units of inheritance are:

Proteins

Chromosomes

Ribosomes

Genes

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

25%

100%

0%

50%

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