1. Inheritance of one gene is also known as

A. Dihybrid inheritance B. Polygenic inheritance C. Monohybrid inheritance D. Linked inheritance

✅ Answer: C

📘 Explanation: Inheritance of one gene studies the transmission of a single character, hence called monohybrid inheritance.

2. Mendel studied inheritance of one gene using which trait?

A. Flower colour B. Seed colour C. Plant height D. Pod shape

✅ Answer: C

📘 Explanation: Mendel explained monohybrid inheritance using plant height (tall and dwarf).

3. Which genotype represents a pure tall pea plant?

A. Tt B. tt C. TT D. tT

✅ Answer: C

📘 Explanation: Pure tall plant is homozygous dominant (TT).

4. Which allele is dominant in Mendel’s height experiment?

A. t B. T C. Both T and t D. None

✅ Answer: B

📘 Explanation: Tall allele (T) is dominant over dwarf allele (t).

5. Which generation is produced by crossing two pure parents?

A. P generation B. F₁ generation C. F₂ generation D. Test generation

✅ Answer: B

📘 Explanation: Crossing two pure parents produces the F₁ generation.

6. All F₁ plants in Mendel’s monohybrid cross were

A. Dwarf B. Tall C. Half tall and half dwarf D. Wrinkled

✅ Answer: B

📘 Explanation: All F₁ plants were tall due to dominance of tall allele.

7. Which law explains uniformity of F₁ generation?

A. Law of segregation B. Law of dominance C. Law of independent assortment D. Law of linkage

✅ Answer: B

📘 Explanation: Dominant allele expresses itself in F₁ generation.

8. What is the genotype of F₁ plants in a monohybrid cross?

A. TT B. tt C. Tt D. TTT

✅ Answer: C

📘 Explanation: All F₁ plants are heterozygous (Tt).

9. Selfing of F₁ plants produces which generation?

A. P B. F₁ C. F₂ D. Test

✅ Answer: C

📘 Explanation: Self-pollination of F₁ plants produces F₂ generation.

10. Which phenotypic ratio is observed in F₂ generation of monohybrid cross?

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

✅ Answer: C

📘 Explanation: F₂ generation shows 3 dominant : 1 recessive.

11. Which genotypic ratio is observed in F₂ generation?

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

✅ Answer: B

📘 Explanation: Genotypic ratio = 1 TT : 2 Tt : 1 tt.

12. Reappearance of dwarf plants in F₂ generation is due to

A. Mutation B. Environmental factors C. Segregation of alleles D. Dominance

✅ Answer: C

📘 Explanation: Alleles segregate during gamete formation.

13. Law of segregation states that

A. Dominant alleles disappear B. Alleles blend together C. Alleles separate during gamete formation D. Traits assort independently

✅ Answer: C

📘 Explanation: Alleles separate so each gamete carries one allele.

14. Law of segregation is also known as

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

✅ Answer: C

📘 Explanation: Gametes are pure and carry only one allele.

15. Which genotype expresses recessive trait?

A. TT B. Tt C. tt D. TTT

✅ Answer: C

📘 Explanation: Recessive traits express only in homozygous condition.

16. Heterozygous genotype for height is

A. TT B. tt C. Tt D. TTT

✅ Answer: C

📘 Explanation: Heterozygous means two different alleles.

17. Which trait appears in F₂ generation but not in F₁ generation?

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

✅ Answer: B

📘 Explanation: Recessive traits reappear in F₂ generation.

18. Test cross is used to determine

A. Phenotype B. Dominance C. Genotype of dominant individual D. Mutation

✅ Answer: C

📘 Explanation: Test cross reveals whether dominant plant is TT or Tt.

19. A test cross involves crossing with

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

✅ Answer: C

📘 Explanation: Test cross uses homozygous recessive parent.

20. If all offspring of test cross are tall, genotype is

A. TT B. Tt C. tt D. TTT

✅ Answer: A

📘 Explanation: Only homozygous dominant produces all dominant offspring.

21. If test cross produces tall and dwarf plants, genotype is

A. TT B. tt C. Tt D. TTT

✅ Answer: C

📘 Explanation: Heterozygous parent produces both phenotypes.

22. Which process causes separation of alleles?

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

✅ Answer: C

📘 Explanation: Alleles separate during meiosis.

23. Chromosomal explanation of Mendel’s laws was given by

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

✅ Answer: C

📘 Explanation: They proposed chromosomal theory of inheritance.

24. Pure breeding lines are always

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

✅ Answer: B

📘 Explanation: Pure lines have identical alleles.

25. Which ratio confirms law of segregation?

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

✅ Answer: C

📘 Explanation: 3:1 phenotypic ratio confirms segregation. 26. Which allele expresses itself even in heterozygous condition?

A. Recessive allele B. Dominant allele C. Lethal allele D. Mutant allele

✅ Correct Answer: B. Dominant allele

📘 Explanation: A dominant allele expresses its trait even when present with a recessive allele (heterozygous condition). Example: In genotype Tt, the tall trait (T) is expressed, not dwarf (t).

27. Which allele expresses itself only in homozygous condition?

A. Dominant allele B. Linked allele C. Recessive allele D. Multiple allele

✅ Correct Answer: C. Recessive allele

📘 Explanation: A recessive allele shows its effect only when both alleles are recessive (tt). It remains hidden in heterozygous condition.

28. Genes controlling a character occur in

A. Single form B. Groups of three C. Pairs D. Chains

✅ Correct Answer: C. Pairs

📘 Explanation: According to Mendel, each character is controlled by a pair of alleles, one inherited from each parent.

29. Mendel studied inheritance by observing

A. Many traits together B. One trait at a time C. Environmental changes D. Chromosomal mutations

✅ Correct Answer: B. One trait at a time

📘 Explanation: In monohybrid crosses, Mendel focused on one character at a time, which helped him derive clear laws of inheritance.

30. All F₁ generation individuals of a monohybrid cross are

A. Different B. Dwarf C. Uniform D. Recessive

✅ Correct Answer: C. Uniform

📘 Explanation: All F₁ individuals show the same phenotype (dominant) due to law of dominance, hence they are uniform.

31. Which genotype always produces tall plants?

A. Tt B. tt C. TT D. tTt

✅ Correct Answer: C. TT

📘 Explanation: TT is homozygous dominant, so it always expresses the tall trait.

32. Which genotype produces dwarf plants?

A. TT B. Tt C. tt D. TTT

✅ Correct Answer: C. tt

📘 Explanation: Only homozygous recessive (tt) genotype expresses dwarfness.

33. Which genotype is heterozygous for plant height?

A. TT B. tt C. Tt D. TTT

✅ Correct Answer: C. Tt

📘 Explanation: Heterozygous genotype contains two different alleles, one dominant and one recessive.

34. Monohybrid cross involves

A. One gene B. Two genes C. Many genes D. Multiple traits

✅ Correct Answer: A. One gene

📘 Explanation: A monohybrid cross studies inheritance of a single gene controlling one trait.

35. Alleles of a gene occupy

A. Different chromosomes B. Same locus on homologous chromosomes C. Cytoplasm D. Ribosomes

✅ Correct Answer: B

📘 Explanation: Alleles are located at the same position (locus) on a pair of homologous chromosomes.

36. Phenotype of an organism depends on its

A. Environment only B. Genotype only C. Genotype and environment D. Chromosome number

✅ Correct Answer: C. Genotype and environment

📘 Explanation: Phenotype is the observable expression influenced by genes and environmental factors.

37. Genotype refers to

A. Physical appearance B. Genetic constitution C. Chromosome size D. Cell structure

✅ Correct Answer: B. Genetic constitution

📘 Explanation: Genotype represents the allelic makeup (TT, Tt, tt) of an organism.

38. Phenotype refers to

A. Gene sequence B. Chromosome number C. Physical appearance D. DNA structure

✅ Correct Answer: C. Physical appearance

📘 Explanation: Phenotype includes visible traits such as height, color, or shape.

39. Variation first appears clearly in which generation?

A. P generation B. F₁ generation C. F₂ generation D. Test generation

✅ Correct Answer: C. F₂ generation

📘 Explanation: In F₂ generation, both dominant and recessive traits appear, showing variation.

40. Law of dominance explains

A. F₂ ratio B. Test cross result C. Uniformity of F₁ generation D. Mutation

✅ Correct Answer: C. Uniformity of F₁ generation

📘 Explanation: Dominant allele masks recessive allele in F₁ generation.

41. Law of segregation explains

A. F₁ generation B. Reappearance of recessive trait C. Independent assortment D. Linkage

✅ Correct Answer: B

📘 Explanation: Segregation of alleles during gamete formation causes recessive traits to reappear in F₂.

42. Phenotypic ratio of monohybrid cross is

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

✅ Correct Answer: C. 3 : 1

📘 Explanation: Three dominant phenotypes and one recessive phenotype appear in F₂ generation.

43. Genotypic ratio of monohybrid cross is

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

✅ Correct Answer: B. 1 : 2 : 1

📘 Explanation: One homozygous dominant, two heterozygous, one homozygous recessive.

44. Tall × Dwarf cross produces all tall plants in

A. P generation B. F₁ generation C. F₂ generation D. Test generation

✅ Correct Answer: B. F₁ generation

📘 Explanation: Due to dominance of tall allele, all F₁ plants are tall.

45. Self-pollination of F₁ plants produces

A. P generation B. Test cross C. F₂ generation D. Hybrid generation

✅ Correct Answer: C. F₂ generation

📘 Explanation: Selfing of heterozygous F₁ plants results in F₂ generation.

46. Recessive allele expresses only in

A. Heterozygous state B. Homozygous state C. Dominant state D. Hybrid state

✅ Correct Answer: B. Homozygous state

📘 Explanation: Two recessive alleles must be present for expression.

47. Test cross always involves

A. Dominant parent B. Heterozygous parent C. Homozygous recessive parent D. F₁ parent

✅ Correct Answer: C

📘 Explanation: Test cross is done with homozygous recessive individual.

48. Inheritance of one gene follows

A. Non-Mendelian pattern B. Mendelian inheritance C. Polygenic inheritance D. Linked inheritance

✅ Correct Answer: B. Mendelian inheritance

📘 Explanation: Single gene inheritance follows Mendel’s laws.

49. Mendel is known as the father of

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

✅ Correct Answer: C. Genetics

📘 Explanation: Mendel discovered basic principles of heredity.

50. Inheritance of one gene explains

A. Complex traits B. Blending inheritance C. Simple hereditary patterns D. Mutation only

✅ Correct Answer: C. Simple hereditary patterns

📘 Explanation: Monohybrid inheritance explains simple, single-gene traits with complete dominance.

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Concepts: Inheritance of One Gene