Biology Inheritance Test Online MCQs

Mustansar KhanLast Updated: October 14, 2025

Important Biology Inheritance Question and Answer

Total Questions:	48
Time Allowed:	25 Minutes
Total Marks:	48
How to Attempt Test:	Please choose the right Option in MCQ-type question.
Test Helpful For:	Biology Test MDCAT Test FPSC/PPSC/SPSC/KPPSC/BPSC/AJKPSC/NTS Biology Interview Question Answer Universities Entrance Test

Biology Inheritance Practice Test Online With Explanation

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1. Gene linkage occurs when:

Genes are located close together on the same chromosome

Genes are silenced

Genes are located on different chromosomes

Genes code for the same protein

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

TT × Tt

TT × tt

Tt × tt

TtRr × TtRr

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

100%

25%

50%

4. Which of the following is a test cross?

TT × Tt

Tt × tt

Tt × Tt

TT × TT

5. Sex-linked genes are mostly located on:

X chromosome

Y chromosome

Mitochondrial DNA

Autosomes

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

Gene linkage

Mutation

Codominance

Crossing over

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

50%

100%

25%

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

9. Which phase of meiosis does crossing over occur?

Telophase I

Anaphase II

Metaphase I

Prophase I

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

25%

50%

100%

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

1:1

1:2:1

3:1

9:3:3:1

12. What does the Law of Independent Assortment explain?

Mutations occur randomly

Each pair of alleles segregates independently during gamete formation

Dominant traits hide recessive ones

Alleles always segregate together

13. What does a test cross help determine?

The blood group

The presence of recessive traits only

Whether an individual is heterozygous or homozygous dominant

The number of chromosomes

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

Only females

Both males and females

Neither

Only males

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

1:1

3:1

1:2:1

9:3:3:1

16. 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

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

Heterozygous

Hybrid

Diploid

Homozygous

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

25%

100%

50%

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

Sons don’t have X chromosomes

Fathers don’t carry defective genes

Fathers only pass the Y chromosome to sons

Sons reject X chromosomes

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

Random recombination

Inherited traits appear together

Greater genetic variation

Traits assort independently

21. What is the purpose of a Punnett square?

To study chromosomes under a microscope

To determine the age of a gene

To identify dominant alleles

To predict the probability of genetic traits

22. In which sex is hemophilia most commonly expressed?

Males

Only children

Females

Both equally

23. What process can separate linked genes?

Crossing over

Transcription

Replication

Translation

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

XʰX

XʰXʰ

25. A recessive allele is expressed only when:

It is dominant over another allele

It is present on a Y chromosome

It is present on both homologous chromosomes

It is on a heterozygous genotype

Page 2 of 2

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

Height and seed shape in pea plants

Blood type in humans

Height in pea plants

Flower color in pea plants

27. Which process leads to genetic recombination?

Crossing over

Replication

Mitosis

Translation

28. In hemophilia, a female must inherit:

One defective Y

One defective X

One defective autosome

Two defective X chromosomes

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

Nucleotides

Traits

Alleles

Chromatids

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

May separate them, increasing variation

Prevents their expression

Has no effect

Ensures they always remain linked

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

Four

One

Two

Three

32. 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

33. What is gene mapping based on?

Physical size of chromosomes

Frequency of crossing over

Shape of DNA

Location of traits

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

Tall

Dwarf

Recessive

Medium height

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

Genotype

Phenotype

Allele

Karyotype

36. What is the significance of independent assortment?

It increases the number of cells

It increases genetic variation

It ensures mutation

It maintains genetic stability

37. Hemophilia primarily affects:

Digestive system

Muscle strength

Nerve function

Blood clotting

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

Tall stem

Wrinkled seeds

White flower

Short stem

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

Diabetes

Sickle-cell anemia

Cancer

Hemophilia

40. The units of inheritance are:

Proteins

Chromosomes

Ribosomes

Genes

41. Which of the following best defines crossing over?

Segregation of alleles during mitosis

Random mutation of DNA

Exchange of segments between non-sister chromatids of homologous chromosomes

Exchange of genetic material between sister chromatids

42. A male inherits his X chromosome from:

Both parents

His father

His mother

Only from autosomes

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

Linked genes

Codominant genes

Recessive genes

Alleles

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

All short

All medium

All tall

50% tall, 50% short

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

50%

25%

75%

100%

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

Darwin

Lamarck

Watson

Mendel

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

Y chromosome protects them

Males have two X chromosomes

Males are more prone to mutations

Males have only one X chromosome

48. What does heterozygous mean?

Having a dominant trait only

Having different alleles

Having two identical alleles

Having one allele

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Mustansar KhanLast Updated: October 14, 2025

Important Biology Inheritance Question and Answer

Biology Inheritance Practice Test Online With Explanation

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