Principles of Inheritance and Variation - Class 12 (Multiple Choice Questions)

1. Externally observable character of an organism is called:

(a) Phenotype

(b) Genotype

(c) Recessive

(d) Dominant

Correct answer: (a) Phenotype

2. The process of transmission characters from generation to generation is:

(a) Variation

(b) Segregation

(c) Migration

(d) Heredity

Correct answer: (d) Heredity

3. What is the scientific name of the plant with which Mendel worked?

(a) Oenothera lamarckiana

(b) Oenothera mendelina

(c) Pisum sativum

(d) Oryza sativa

Correct answer: (c) Pisum Sativum

4. When a hybrid tall pea is cross fertilized by a pure dwarf the ratio of tall to dwarf grown from the seeds will be:

(a) 3:1

(b) 2:1

(c) 1:3

(d) 1:1

Correct answer: (d) 1:1

5. What are the gene pairs signifying a trait called?

(a) Hybrid

(b) Phenotype

(c) Pure-line

(d) Alleles

Correct answer: (d) Alleles

6. Who postulated the law of inheritance?

(a) Lamarck

(b) Darwin

(c) Mendel

(d) Haeckel

Correct answer: (c) Mendel

7. When heterozygous round seeded plant is crossed with a recessive wrinkled seeded plant then round and wrinkle phenotypes will appear in F₁ in the ratio:

(a) 1:2

(b) 2:1

(c) 1:1

(d) 3:1

Correct answer: (c) 1:1

8. What is the phenotypic ratio in F2 generation of Mendelian monohybrid cross?

(a) 1:1

(b) 2:1

(c) 3:1

(d) 9:3:3:1

Correct answer: (c) 3:1

9. What is the genotypic ratio in F2 generation of Mendelian monohybrid cross?

(a) 1:1

(b) 3:1

(c) 1:2

(d) 1:2:1

Correct answer: (d) 1:2:1

10. Character that is expressed in hybrid is:

(a) Dominant

(b) Recessive

(c) Multiple

(d) None of these

Correct answer: (a) Dominant

11. Character that is suppressed in heterozygous state is called:

(a) Dominant

(b) Recessive

(c) Suppressed

(d) Overshadowed

Correct answer: (b) Recessive

12. Mendel succeeded in his experiments because:

(a) He selected pea plants.

(b) Independent characters were studied.

(c) A lot of characters were selected.

(d) Pea plant is bisexual.

Correct answer: (b) Independent characters were studied.

13. In F₂ generation of a monohybrid cross in what ratio the recessive character appears?

(a) 1/2

(b) 1/4

(c) 3/4

(d) 1

Correct answer: (b) 1/4

14. In a Mendelian hybrid experiment, F₁ plants are:

(a) Heterozygous

(b) Homozygous

(c) Hemizygous

(d) Dizygous

Correct answer: (a) Heterozygous

15. The character which predominates and clearly seen in F₁ generation is:

(a) Intermediate

(b) Incomplete

(c) Recessive

(d) Dominant

Correct answer: (d) Dominant

16. The term back cross refers to:

(a) A cross among F₁ hybrid

(b) A cross between F₁ hybrid and either of parents

(c) A cross between F₁ and F₂ plants

(d) None of these

Correct answer: (b) A cross between F₁ hybrid and either of parents 

17. Which of the following ratio represents a test cross?

(a) 3:1

(b) 9:3:3:1

(c) 1:2:1

(d) 1:1:1:1

Correct answer: (d) 1:1:1:1

18. When the F₂ phenotypic and genotypic ratios are same, it is a case of:

(a) Dominance

(b) Incomplete dominance

(c) Test cross

(d) Back cross

Correct answer: (b) Incomplete dominance

19. A gamete contains how many alleles of a gene?

(a) One

(b) Two

(c) All

(d) None

Correct answer: (a) One

20. Find out the genotype(s) of the offspring of the cross AaBb ⨯ aabb.

(a) AaBb

(b) Aabb

(c) AaBb and aabb

(d) AaBb, Aabb, aaBb and aabb

Correct answer: (d) AaBb, Aabb, aaBb and aabb

21. A cross between AaBB ⨯ aaBB produces the offspring with genotypes:

(a) 1 AaBB : 3 aaBB

(b) 3 AaBB : 1 aaBB

(c) 1 AaBB : 1 aaBB

(d) All AaBB

Correct answer: (c) 1 AaBB : 1 aaBB

22. An allele is said to be dominant if it is expressed in:

(a) Heterozygous condition only

(b) Homozygous condition only

(c) Both heterozygous and homozygous conditions

(d) Gametes

Correct answer: (c) Both heterozygous and homozygous conditions

23. Percentage of recessive phenotype in a cross between two hybrids is:

(a) 25%

(b) 50%

(c) 75%

(d) 100%

Correct answer: (a) 25%

24. What will be the percentage of tall plants with red flowers in a cross between TTRr ⨯ ttrr, when T stands for tall dominant and R for red dominant?

(a) 25%

(b) 50%

(c) 75%

(d) 100%

Correct answer: (b) 50%

25. In humans polygenes are responsible for:

(a) Albinism

(b) Haemophilia

(c) Colour blindness

(d) Skin Colour

Correct answer: (d) Skin Colour

26. An F₂ genotypic ratio of 1:4:6:4:1 instead of 9:3:3:1 indicates:

(a) Qualitative inheritance

(b) Quantitative inheritance

(c) Incomplete dominance

(d) Multiple allelism

Correct answer: (b) Quantitative inheritance

27. Organisms phenotypically similar but genotypically different are:

(a) Heterozygotes

(b) Homozygotes

(c) Monozygotes

(d) Multizygotes

Correct answer: (a) Heterozygotes

28. In order to find out the different types of gametes produced by a pea plant having the genotypes AaBb, it should be crossed to a plant with genotype:

(a) AABB

(b) AaBb

(c) aabb

(d) aaBB

Correct answer: (c) aabb

29. Which of the following is most suitable medium for culture of Drosophila melanogaster?

(a) Cow dung

(b) Moist bread

(c) Agar agar

(d) Ripe banana

Correct answer: (d) Ripe banana

30. In Mendel's experiments  with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), yellow cotyledon (YY) was dominant over green cotyledon (yy). What are the expected phenotypes in the F₂ generation of the cross RRYY ⨯ rrYY?

(a) Round seeds with yellow cotyledons and wrinkled seeds with yellow cotyledons

(b) Only round seeds with green cotyledons

(c) Only wrinkled seeds with yellow cotyledons

(d) Only wrinkled seeds with green cotyledons

Correct answer: (a) Round seeds with yellow cotyledons and wrinkled seeds with yellow cotyledons

31. Which one of the following pairs of features is a good example of polygenic inheritance?

(a) Human height and skin colour

(b) ABO blood group in humans and flower colour of Mirabilis jalapa

(c) Hair pigment of mouse and tongue rolling of humans

(d) Human eye colour and sickle-cell anaemia

Correct answer: (a) Human height and skin colour

32. Mating of an organism to a double recessive in order to determine whether it is homozygous or heterozygous for a character under consideration is called:

(a) Reciprocal cross

(b) Test cross

(c) Dihybrid cross

(d) Back cross

Correct answer: (b) Test cross

33. Two pea plants were subjected cross pollination. Of the 183 plants produced in the next generation, 94 plants were found to be tal and 89 plants were found to be dwarf. The genotype of the two parental plants are likely to be:

(a) TT and tt

(b) Tt and Tt

(c) Tt and tt

(d) TT and TT

Correct answer: (c) Tt and tt

34. The F₂ generation offspring in a plant showing incomplete dominance exhibit:

(a) Variable genotypic and phenotypic ratios

(b) A genotypic ratio of 1:1

(c) A phenotypic ratio of 3:1

(d) Similar phenotypic and genotypic ratios of 1:2:1

Correct answer: (d) Similar phenotypic and genotypic ratios of 1:2:1

35. Discontinuous variations are:

(a) Acquired characters

(b) Mutations

(c) Essential features

(d) Non-essential features

Correct answer: (b) Mutation

36. When a hybrid tall pea plant is cross fertilized with a dwarf pea plant, the ratio of tall is to dwarf plants grown from the seeds will be:

(a) 3:1

(b) 2:1

(c) 1:3

(d) 1:1

Correct answer: (d) 1:1

37. Law of segregation explains expression of recessive characters in:

(a) Parental generation

(b) F₁ generation

(c) F₂ generation

(d) All of these

Correct answer: (b) F₁ generation

38. A cross between an organism with dominant phenotype and a homozygous recessive to know the genotype of former is called:

(a) Back cross

(b) Test cross

(c) Reciprocal cross

(d) Monohybrid cross

Correct answer: (b) Test cross

39. After a cross of tall plant and dwarf plant, in F₁ generation ratio of tall : dwarf is 50:50. What are the genotypes of parents?

(a) Tall heterozygous, dwarf homozygous

(b) Both homozygous

(c) Both heterozygous

(d) Dwarf heterozygous, tall homozygous

Correct answer: (a) Tall heterozygous, dwarf homozygous

40. A pair of contrasting characteristics is called:

(a) Phenotype

(b) Genotype

(c) Allele

(d) Gene

Correct answer: (c) Allele

41. A couple with blood groups A ad B may have children with blood groups:

(a) A and B only

(b) A, B and AB

(c) A, B, AB and O

(d) AB only

Correct answer: (c) A, B, AB and O

42. Which of the following ratio represents a test cross?

(a) 3:1

(b) 9:3:3:1

(c) 1:2:1

(d) 1:1:1:1

Correct answer: (d) 1:1:1:1

43. A ratio of 1:4:6:4:1 in F2 indicates which type of inheritance?

(a) Monogenic

(b) Qualitative

(c) Quantitative

(d) Incomplete

Correct answer: (c) Quantitative

44. Which term was used by Mendel to represent hereditary unit?

(a) Gene

(b) Allele

(c) Factor

(d) Elemente

Correct answer: (c) Factor

45. Right-handedness is dominant over left-handedness. Most probable gene types having two right-handed parents, a left handed child are:

(a) RR ⨯ RR

(b) RR ⨯ Rr

(c) Rr ⨯ Rr

(d) All of these

Correct answer: (c) Rr ⨯ Rr

46. What types of genotypes are expected when a plant with AABb genotype is self-pollinated?

(a) 3 AABB : 1 AABb

(b) 3 AABB : 1 AAbb

(c) 1 AABB : 1 AAbb

(d) 1 AABB : 2 AABb : 1 AAbb

Correct answer: (d) 1 AABB : 2 AABb : 1 AAbb

47. Which one of the following is an example of polygenic inheritance?

(a) Skin colour in humans

(b) Flower colour in Mirabilis jalapa

(c) Production of male honeybee

(d) Pod shape in garden pea

Correct answer: (a) Skin colour in humans

48. How many different kinds of gametes will be produced by a plant having the genotype AABbCC?

(a) Two

(b) Three

(c) Four

(d)  Nine

Correct answer: (a) Two

49. Test cross involves:

(a) Crossing between two genoypes with dominant traits

(b) Crossing between two genotypes with recessive traits

(c) Crossing between two F1 hybrids

(d) Crossing the F1 hybrid with a double recessive genotype

Correct answer: (d) Crossing the F1 hybrid with a double recessive genotype

50. A pure tall and a pure dwarf plant were crossed to produce offsprings. Offsprings were self-crossed, then find out the ratio between true breeding tall to true breeding dwarf?

(a) 1:1

(b) 3:1

(c) 2:1

(d) 1:2:1

Correct answer: (a) 1:1

51. Genetics term was proposed by

(a) Mendel 

(b) Bateson

(c) Morgan

(d) Johannson

Correct answer: (b) Bateson

52. Mother homozygous B, and father is A. What will be the possible blood group in their progeny?

(a) AB & B possible

(b) AB & A possible

(c) A & B possible

(d) O possible

Correct answer: (a) AB & B possible

53. In ABO blood groups, how many phenotypes are found?

(a) 6

(b) 8

(c) 1

(d) 4

Correct answer: (d) 4

54. When a tall plant with round seeds (TTRR) crossed with a dwarf plant with wrinkle seeds (ttrr), the F1 generation consists of tall plants with round seeds. What would be the proportion of dwarf plant with wrinkle seeds in F1 generation?

(a) 1/4

(b) 1/16

(c) 0

(d) 1/2

Correct answer: (c) 0

55. In man, the blue eye colour is recessive to the brown eye colour. If the boy has brown eye and his mother is blue eyed, what would be the phenotype of his father?

(a) Black eye

(b) Brown eye

(c) Green eye

(d) Blue eye

Correct answer: (b) Brown eye

56. A common test to find the genotype of a hybrid is by:

(a) Crossing of one F2 progeny with female parent

(b) Studying the sexual behaviour of F1 progenies

(c) Crossing of one F1 progeny with male parent

(d) Crossing of one F2 progeny with male parent

Correct answer: (c) Crossing of one F1 progeny with male parent

57. Inheritances of skin colour in humans is an example of:

(a) Point mutation

(b) Polygenic inheritance

(c) Codominance

(d) Chromosomal aberration

Correct answer: (b) Polygenic inheritance

58. In pea plants, yellow seeds are dominant to green. If a heterozygous yellow seeded plant is crossed with  with a green seeded plant, what ratio of yellow and green seeded plants would you expect in F1 generation?

(a) 9:1

(b) 1:3

(c) 3:1

(d) 50:50

Correct answer: (d) 50:50

59. The offsprings of mating between two pure strains are called as:

(a) Heterosis

(b) Hybrid

(c) Progeny

(d) Cybrid

Correct answer: (b) Hybrid

60. G. Mendel used the plant:

(a) Oenothera lamarkiana

(b) Lathyrus sativus

(c) Mirabilis jalapa

(d) Pisum sativum

Correct answer: (d) Pisum sativum