1. Who is known as the Father of Genetics?

A. Charles Darwin B. Hugo de Vries C. Gregor Johann Mendel D. Thomas Hunt Morgan

✅ Correct Answer: C

📘 Explanation: Gregor Johann Mendel conducted systematic experiments on pea plants and discovered the fundamental laws governing inheritance of traits. His work laid the foundation of genetics, earning him the title Father of Genetics.

2. Mendel performed his experiments on which plant?

A. Wheat B. Maize C. Pea plant D. Rice

✅ Correct Answer: C

📘 Explanation: Mendel chose pea plants (Pisum sativum) because they have clear contrasting traits, a short life cycle, natural self-pollination, and can be cross-pollinated easily.

3. Which of the following characters of pea plant is dominant?

A. Wrinkled seed B. Green seed C. Dwarf plant D. Round seed

✅ Correct Answer: D

📘 Explanation: Round seed shape is dominant over wrinkled seed shape. A dominant trait expresses itself even when present in only one copy.

4. The alternative forms of a gene are called

A. Genotype B. Phenotype C. Alleles D. Chromosomes

✅ Correct Answer: C

📘 Explanation: Alleles are different forms of the same gene occupying the same position (locus) on homologous chromosomes.

5. Which law states that one allele can mask the expression of another?

A. Law of Segregation B. Law of Dominance C. Law of Independent Assortment D. Chromosomal theory

✅ Correct Answer: B

📘 Explanation: The Law of Dominance states that in a heterozygous condition, the dominant allele expresses itself while the recessive allele remains unexpressed.

6. What is the phenotypic ratio in F₂ generation of a monohybrid cross?

A. 1 : 1 B. 1 : 2 : 1 C. 3 : 1 D. 9 : 3 : 3 : 1

✅ Correct Answer: C

📘 Explanation: In a monohybrid cross, F₂ generation shows 3 dominant : 1 recessive phenotypic ratio due to segregation of alleles.

7. What is the genotypic ratio in F₂ generation of a monohybrid cross?

A. 3 : 1 B. 1 : 2 : 1 C. 9 : 3 : 3 : 1 D. 2 : 1

✅ Correct Answer: B

📘 Explanation: The genotypic ratio is 1 homozygous dominant : 2 heterozygous : 1 homozygous recessive.

8. Law of Segregation is also called

A. Law of linkage B. Law of purity of gametes C. Law of dominance D. Law of blending

✅ Correct Answer: B

📘 Explanation: During gamete formation, alleles separate so each gamete receives only one allele, maintaining genetic purity.

9. Recessive trait reappears in which generation?

A. Parental B. F₁ C. F₂ D. F₃

✅ Correct Answer: C

📘 Explanation: The recessive trait is masked in F₁ but reappears in F₂ due to segregation of alleles.

10. Which cross studies inheritance of two traits simultaneously?

A. Test cross B. Back cross C. Monohybrid cross D. Dihybrid cross

✅ Correct Answer: D

📘 Explanation: A dihybrid cross involves two pairs of contrasting traits, such as seed shape and seed color.

11. The phenotypic ratio in F₂ generation of a dihybrid cross is

A. 3 : 1 B. 1 : 2 : 1 C. 9 : 3 : 3 : 1 D. 12 : 3 : 1

✅ Correct Answer: C

📘 Explanation: The 9:3:3:1 ratio confirms independent assortment of genes.

12. Law of Independent Assortment applies to genes that are

A. Linked B. On same chromosome C. On different chromosomes D. Recessive

✅ Correct Answer: C

📘 Explanation: Genes located on different chromosomes assort independently during gamete formation.

13. Which of the following traits is recessive in pea plant?

A. Tall plant B. Purple flower C. Green seed D. Round seed

✅ Correct Answer: C

📘 Explanation: Green seed color is recessive to yellow seed color.

14. An organism with genotype Tt is called

A. Homozygous B. Heterozygous C. Pure D. Hybrid sterile

✅ Correct Answer: B

📘 Explanation: Heterozygous organisms possess two different alleles for a trait.

15. Homozygous condition means

A. Presence of two different alleles B. Presence of only one allele C. Presence of identical alleles D. Absence of alleles

✅ Correct Answer: C

📘 Explanation: Homozygous individuals carry two identical alleles (TT or tt).

16. Which generation is always uniform?

A. Parental B. F₁ C. F₂ D. F₃

✅ Correct Answer: B

📘 Explanation: All individuals of F₁ generation show the dominant phenotype due to law of dominance.

17. The physical appearance of an organism is called

A. Genotype B. Allele C. Phenotype D. Gene

✅ Correct Answer: C

📘 Explanation: Phenotype refers to observable characteristics like height, color, or shape.

18. The genetic makeup of an organism is called

A. Phenotype B. Genotype C. Allele D. Chromosome

✅ Correct Answer: B

📘 Explanation: Genotype represents the allelic composition of an organism.

19. Mendel studied how many contrasting traits?

A. 5 B. 6 C. 7 D. 8

✅ Correct Answer: C

📘 Explanation: Mendel studied seven pairs of contrasting traits in pea plants.

20. Which of the following does NOT obey Mendel’s law of dominance?

A. Complete dominance B. Codominance C. Monohybrid cross D. Dihybrid cross

✅ Correct Answer: B

📘 Explanation: In codominance, both alleles express themselves equally, violating dominance.

21. TT × tt produces F₁ plants that are

A. All dwarf B. All tall C. Half tall, half dwarf D. All wrinkled

✅ Correct Answer: B

📘 Explanation: All F₁ plants are heterozygous (Tt) and express tallness due to dominance.

22. Genes are located on

A. RNA B. Ribosomes C. Chromosomes D. Cytoplasm

✅ Correct Answer: C

📘 Explanation: Genes are segments of DNA located on chromosomes.

23. Chromosomal theory of inheritance was proposed by

A. Watson and Crick B. Darwin C. Sutton and Boveri D. Mendel

✅ Correct Answer: C

📘 Explanation: They explained that genes are carried on chromosomes and follow Mendel’s laws.

24. Crossing an individual with homozygous recessive is called

A. Back cross B. Test cross C. Self cross D. Hybrid cross

✅ Correct Answer: B

📘 Explanation: Test cross helps determine the genotype of an organism showing dominant trait.

25. Which ratio indicates genotypic ratio?

A. 3 : 1 B. 9 : 3 : 3 : 1 C. 1 : 2 : 1 D. 2 : 1

✅ Correct Answer: C

📘 Explanation: 1:2:1 represents distribution of genotypes.

26. Independent assortment occurs during

A. Mitosis B. Meiosis C. Fertilization D. Transcription

✅ Correct Answer: B

📘 Explanation: Independent assortment happens during meiosis when chromosomes separate.

27. Linked genes do not follow

A. Law of segregation B. Law of dominance C. Law of independent assortment D. Chromosomal theory

✅ Correct Answer: C

📘 Explanation: Linked genes are inherited together, violating independent assortment.

28. Pure breeding lines are always

A. Heterozygous B. Homozygous C. Sterile D. Hybrid

✅ Correct Answer: B

📘 Explanation: Pure lines consistently produce same traits generation after generation.

29. Number of gametes produced by RrYy genotype is

A. 2 B. 3 C. 4 D. 8

✅ Correct Answer: C

📘 Explanation: RrYy produces four types of gametes: RY, Ry, rY, ry.

30. Mendel’s experiments were based on

A. Observation only B. Guesswork C. Statistical analysis D. Computer models

✅ Correct Answer: C

📘 Explanation: Mendel carefully counted offspring and applied mathematical ratios.

31. Which trait is dominant in pea plant?

A. Dwarf stem B. White flower C. Wrinkled seed D. Tall stem

✅ Correct Answer: D

📘 Explanation: Tall stem is dominant over dwarf stem.

32. Law of segregation explains

A. Expression of dominant trait B. Separation of alleles C. Independent inheritance

D. Mutation

✅ Correct Answer: B

33. Which generation shows maximum variation?

A. P B. F₁ C. F₂ D. F₃

✅ Correct Answer: C

📘 Explanation: F₂ generation shows recombination of traits.

34. Mendel’s work was rediscovered in

A. 1856 B. 1865 C. 1900 D. 1920

✅ Correct Answer: C

35. The basic unit of inheritance is

A. Chromosome B. Gene C. Allele D. DNA

✅ Correct Answer: B

36. Which cross confirms genotype of dominant phenotype?

A. Monohybrid B. Dihybrid C. Test cross D. Back cross

✅ Correct Answer: C

37. Which is NOT a Mendelian ratio?

A. 3 : 1 B. 1 : 2 : 1 C. 9 : 3 : 3 : 1 D. 2 : 1

✅ Correct Answer: D

38. Recessive allele is expressed when

A. Dominant allele is present B. Heterozygous C. Homozygous D. Linked

✅ Correct Answer: C

39. Law of dominance applies to

A. Homozygous recessive B. Heterozygous condition C. Polygenic traits D. Linked genes

✅ Correct Answer: B _

40. Which trait reappears in F₂ generation?

A. Dominant B. Recessive C. Hybrid D. Lethal

✅ Correct Answer: B

41. TT represents which of the following genotypes?

A. Homozygous recessive B. Heterozygous C. Homozygous dominant D. Hybrid

✅ Correct Answer: C. Homozygous dominant

📘 Detailed Explanation: The genotype TT consists of two identical dominant alleles.

Homozygous → both alleles are the same
Dominant → allele that expresses itself

Thus, TT is a homozygous dominant genotype, which always expresses the dominant trait (e.g., tall plant).

42. The genotype “tt” represents

A. Homozygous dominant B. Heterozygous C. Homozygous recessive D. Hybrid dominant

✅ Correct Answer: C. Homozygous recessive

📘 Detailed Explanation: The genotype tt contains two identical recessive alleles.
A recessive trait expresses itself only when present in homozygous condition.
Hence, tt is called homozygous recessive, and it produces the recessive phenotype (e.g., dwarf plant).

43. Mendel used which organism to study inheritance?

A. Frog B. Drosophila C. Pea plant D. Bacteria

✅ Correct Answer: C. Pea plant

📘 Detailed Explanation: Gregor Mendel used the pea plant (Pisum sativum) because:

It has distinct contrasting traits
It shows self-pollination and cross-pollination
It has a short life cycle
It produces large number of seeds

These features made pea plant ideal for genetic experiments.

44. The phenotypic ratio 9 : 3 : 3 : 1 is obtained in

A. Monohybrid cross B. Test cross C. Back cross D. Dihybrid cross

✅ Correct Answer: D. Dihybrid cross

📘 Detailed Explanation: A dihybrid cross involves inheritance of two traits at the same time. In the F₂ generation of a dihybrid cross, Mendel observed the phenotypic ratio:

9 → Dominant for both traits
3 → Dominant for first, recessive for second
3 → Recessive for first, dominant for second
1 → Recessive for both traits

This 9:3:3:1 ratio supports the Law of Independent Assortment.

45. Separation of alleles during gamete formation occurs during

A. Mitosis B. Fertilization C. Meiosis D. Transcription

✅ Correct Answer: C. Meiosis

📘 Detailed Explanation: During meiosis, homologous chromosomes separate, leading to separation of alleles.
This process explains the Law of Segregation, which states that alleles do not blend and each gamete carries only one allele.

46. Independent assortment of genes occurs when genes are

A. Located close together B. Located on the same chromosome C. Located on different chromosomes D. Recessive in nature

✅ Correct Answer: C. Located on different chromosomes

📘 Detailed Explanation: The Law of Independent Assortment applies only to genes that are:

Present on different chromosomes
Or far apart on the same chromosome

Such genes assort independently during gamete formation, producing new combinations.

47. An organism having two different alleles for a character is called

A. Homozygous B. Pure line C. Heterozygous D. Recessive

✅ Correct Answer: C. Heterozygous

📘 Detailed Explanation: A heterozygous organism has:

Two different alleles (e.g., Tt)
One dominant and one recessive allele

The dominant allele expresses itself, while the recessive remains hidden.

48. Phenotypic ratio refers to the ratio of

A. Genes B. Chromosomes C. Observable traits D. Alleles

✅ Correct Answer: C. Observable traits

📘 Detailed Explanation: Phenotype means physical appearance or observable characters, such as:

Tall or dwarf
Round or wrinkled seeds

Thus, phenotypic ratio is the ratio of visible traits seen in offspring.

49. Genotypic ratio represents the ratio of

A. Visible traits B. Genetic constitution C. Chromosome number D. Cell division stages

✅ Correct Answer: B. Genetic constitution

📘 Detailed Explanation: Genotype refers to the genetic makeup of an organism (e.g., TT, Tt, tt).
Genotypic ratio shows the distribution of different genotypes in offspring.

50. Mendel’s laws are considered the foundation of

A. Evolution B. Biotechnology C. Genetics D. Ecology

✅ Correct Answer: C. Genetics

📘 Detailed Explanation: Mendel’s laws explain:

How traits are inherited
How alleles behave during reproduction

These principles form the basic framework of genetics, influencing modern biology, medicine, and biotechnology.

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CH 4: Principles of Inheritance and Variation