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. In hemophilia, a female must inherit:

One defective autosome

Two defective X chromosomes

One defective Y

One defective X

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

50%

25%

0%

100%

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

Nucleotides

Traits

Alleles

Chromatids

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

Both males and females

Only females

Neither

Only males

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5. In which sex is hemophilia most commonly expressed?

Males

Females

Only children

Both equally

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6. What is gene mapping based on?

Location of traits

Shape of DNA

Frequency of crossing over

Physical size of chromosomes

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7. 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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8. A male inherits his X chromosome from:

Both parents

His father

Only from autosomes

His mother

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9. The units of inheritance are:

Genes

Proteins

Chromosomes

Ribosomes

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

Wrinkled seeds

Tall stem

Short stem

White flower

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11. What is the purpose of a Punnett square?

To determine the age of a gene

To study chromosomes under a microscope

To predict the probability of genetic traits

To identify dominant alleles

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

TtRr × TtRr

TT × tt

TT × Tt

Tt × tt

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

Diabetes

Cancer

Sickle-cell anemia

Hemophilia

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

Linked genes

Codominant genes

Alleles

Recessive genes

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15. Which process leads to genetic recombination?

Mitosis

Crossing over

Replication

Translation

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

Genotype

Allele

Phenotype

Karyotype

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

Dwarf

Medium height

Recessive

Tall

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

Codominance

Mutation

Crossing over

Gene linkage

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

9:3:3:1

1:1

3:1

1:2:1

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

100%

0%

50%

25%

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21. 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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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 does a test cross help determine?

The blood group

The number of chromosomes

The presence of recessive traits only

Whether an individual is heterozygous or homozygous dominant

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24. What process can separate linked genes?

Translation

Transcription

Crossing over

Replication

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25. Which of the following is a test cross?

TT × TT

Tt × Tt

TT × Tt

Tt × tt

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

Heterozygous

Hybrid

Homozygous

Diploid

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27. What is the significance of independent assortment?

It increases the number of cells

It ensures mutation

It maintains genetic stability

It increases genetic variation

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

Sons reject X chromosomes

Sons don’t have X chromosomes

Fathers only pass the Y chromosome to sons

Fathers don’t carry defective genes

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

XY

XʰX

XʰXʰ

XX

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30. A recessive allele is expressed only when:

It is dominant over another allele

It is present on both homologous chromosomes

It is present on a Y chromosome

It is on a heterozygous genotype

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

Carrier father

Normal mother

Affected father

Carrier mother

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32. Which of the following best defines crossing over?

Random mutation of DNA

Exchange of segments between non-sister chromatids of homologous chromosomes

Exchange of genetic material between sister chromatids

Segregation of alleles during mitosis

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

One

Two

Four

Three

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

3:1

9:3:3:1

1:2:1

1:1

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

8

2

1

4

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

25%

50%

100%

0%

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37. Hemophilia primarily affects:

Muscle strength

Blood clotting

Digestive system

Nerve function

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

100%

50%

75%

25%

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39. Which phase of meiosis does crossing over occur?

Anaphase II

Prophase I

Telophase I

Metaphase I

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

Has no effect

Prevents their expression

Ensures they always remain linked

May separate them, increasing variation

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

Alleles for a trait separate during gamete formation

Dominant traits are always expressed

Genes always blend in offspring

Traits are inherited in pairs

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

Greater genetic variation

Inherited traits appear together

Random recombination

Traits assort independently

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43. What does heterozygous mean?

Having two identical alleles

Having a dominant trait only

Having one allele

Having different alleles

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44. Gene linkage occurs when:

Genes code for the same protein

Genes are silenced

Genes are located on different chromosomes

Genes are located close together on the same chromosome

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

Height in pea plants

Blood type in humans

Height and seed shape in pea plants

Flower color in pea plants

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46. Sex-linked genes are mostly located on:

Mitochondrial DNA

Autosomes

X chromosome

Y chromosome

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

Lamarck

Mendel

Darwin

Watson

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48. What does the Law of Independent Assortment explain?

Mutations occur randomly

Alleles always segregate together

Each pair of alleles segregates independently during gamete formation

Dominant traits hide recessive ones

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