Principles of Inheritance and Variation MCQs with Answers

Question-1. If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is

1. autosomal dominant
2. autosomal recessive
3. sex-linked dominant
4. sex-linked recessive.

Question-2. In sickle cell anaemia glutamic acid is replaced by valine. Which one of the following triplets codes for valine ?

1. GGG
2. A AG
3. G A A
4. GUG

Question-3. _________ pairs of contrasting traits were studied by Mendel in pea plant.

1. 6
2. 7
3. 8
4. 10

Question-4. A couple has six daughters. What is the possibility of their having a girl next time ?

1. 10%
2. 50%
3. 90%
4. 100%

Question-5. A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents ?

1. TT and Tt
2. Tt and Tt
3. TT and TT
4. Tt and It

Question-6. A recessive allele is expressed in

1. heterozygous condition only
2. homozygous condition only
3. F3 generation
4. both homozygous and heterozygous conditions.

Question-7. ABO blood grouping in human beings cites the example of

1. incomplete dominance
2. co-dominance
3. multiple allelism
4. both(b) and (c)

Question-8. All genes located on the same chromosome

1. form different groups depending upon their relative distance
2. form one linkage group
3. will not from any linkage groups
4. form interactive groups that affect the phenotype.

Question-9. Chromosomal theory of inheritance was given by

1. Morgan et al
2. Sutton and Boveri
3. Hugo deVries
4. Gregor J. Mendel

Question-10. Chromosome maps/genetic maps were first prepared by

1. Sutton and Boveri (1902)
2. Bateson and Punnett (1906)
3. Morgan (1910)
4. Sturtevant (1911)

Question-11. Conditions of a karyotype 2n±l and 2n + 2 are called

1. aneuploidy
2. polyploidy
3. allopolyploidy
4. monosomy.

Question-12. Distance between the genes and percentage of recontbfnatidnshows

1. a direct relationship
2. an inverse relationship
3. a parallel relationship
4. no relationship.

Question-13. Failure of segregation of chromatids during cell division results in the gain or loss of chromosomes, this is called as

1. euploidy
2. monoploidy
3. aneuploidy
4. polyploidy

Question-14. Females with Turner’s syndrome have

1. small uterus
2. rudimentary ovaries
3. underdeveloped breasts
4. all of these.

Question-15. Genes located very close to one another on same chromosome tend to be transmitted together and are called as

1. allelomorphs
2. identical genes
3. linked genes
4. recessive genes

Question-16. Genes which code for a pair of contrasting traits are known as

1. dominant genes
2. alleles
3. linked genes
4. none of these

Question-17. Grasshopper is an example of XO type of sex determination in which the males have

1. one X chromosome
2. one Y chromosome
3. two X chromosomes
4. no X chromosome

Question-18. Haplodiploidy is found in

1. grasshoppers and cockroaches
2. birds and reptiles
3. butterflies and moths
4. honeybees, ants and waspe.

Question-19. How many types of gametes can be produced by a diploid organism who is heterozygous for 4 loci ?

1. 4
2. 8
3. 16
4. 32

Question-20. If both parents are carriers for thalassaemia, which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child ?

1. 25%
2. 100%
3. No chance
4. 50%

Question-21. If linkage was known at the time of Mendel then which of the following laws, he would not have been able to explain ?

1. Law of dominance
2. Law of independent assortment
3. Law of segregation
4. Law of purity of gametes

Question-22. In a dihybrid cross, if you get 9 : 3 : 3 : 1 ratio it denotes that

1. the alleles of two genes are interacting with each other
2. it is a multigenic inheritance
3. it is a case of multiple allelism
4. the alleles of two genes are segregating independently.

Question-23. In a monohybrid cross between two heterozygous individuals, percentage of pure homozygous individuals obtained in F1 generation will be

1. 25%
2. 50%
3. 75%
4. 100%

Question-24. In Antirrhinum (dog flower), phenotypic ratio in F2 generation for the inheritance of flower colour would be

1. 3 : 1
2. 1 : 2 : 1
3. 1 : 1
4. 2 : 1

Question-25. In mice, Y is the dominant allele for yellow fur an y is the recessive allele for grey fur. Since Y is lethal when homozygous, the result of cross Yy × Yy will be

1. 3 yellow : 1 grey
2. 2 yellow : 1 grey
3. 1 yellow : 1 grey
4. 1 yellow : 2 grey

Question-26. In the F2 generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are

1. phenotypes – 4; genotypes – 16
2. phenotypes – 9; genotypes – 4
3. phenotypes – 4; genotypes – 8
4. phenotypes – 4; genotypes – 9.

Question-27. In XO type of sex determination

1. females produce two different types of gametes
2. males produce two different types of gametes
3. females produce gametes with Y chromosome
4. males produce gametes with Y chromosome.

Question-28. Inheritance of roan coat in cattle is an example of

1. incomplete dominance
2. codominance
3. multiple allelism
4. none of these

Question-29. Klinefelter’s syndrome is characterised by a karyotype of

1. XYY
2. XO
3. XXX
4. XXY

Question-30. Law of independent assortment can be explained with the help of

1. dihybrid
2. test cross
3. back cross
4. monohybrid cross

Question-31. Mendal formulated the law of purity of gametes on the basis of

1. monohybrid cross
2. dihybrid cross
3. test cross
4. back cross.

Question-32. Mendel’s law of independent assortment does not hold true for the genes that are located closely on

1. same chromosome
2. non-homologous chromosomes
3. X-chromosome
4. autosomes

Question-33. Mendel’s Law of independent assortment holds good for genes situated on the

1. non-homologous chromosomes
2. homologous chromosomes
3. extra nuclear genetic element
4. same chromosome.

Question-34. Mendel’s work was rediscovered by three scientists in the year

1. 1865
2. 1900
3. 1910
4. 1920

Question-35. Mongolism is a genetic disorder which is caused by the presence of an extra chromosome number

1. 20
2. 21
3. 17
4. 23

Question-36. Number of autosomes present in liver cells of a human female is

1. 22 autosomes
2. 22 pairs
3. 23 autosomes
4. 23 pairs

Question-37. Occasionally, a single gene may express more than one effect. The phenomenon is called

1. multiple allelism
2. mosaicism
3. pleiotropy
4. polygeny.

Question-38. Person having genotype IA IB would show the blood group as AB. This is because of

1. pleiotropy
2. co-dominance
3. segregation
4. incomplete dominance.

Question-39. Phenotypic and genotypic ratio is similar in case of

1. complete dominance
2. incomplete dominance
3. over dominance
4. epistasis.

Question-40. Rate of mutation is affected by

1. temperature
2. X-rays
3. gamma rays
4. all of these.

Question-41. Select the disease which is caused by recessive autosomal genes when present in homozygous conditions.

1. Alkaptonuria
2. Albinism
3. Cystic fibrosis
4. All of these

Question-42. Select the incorrect statement regarding pedigree analysis.

1. Solid symbols show unaffected individuals.
2. Proband is the person from which case history starts.
3. It is useful for genetic counsellors.
4. It is an analysis of traits in several generations of a family.

Question-43. The characters which appear in the first filial generation are called

1. recessive characters
2. dominant characters
3. holandric characters
4. lethal characters

Question-44. The colour based contrasting traits in seven contrasting pairs, studied by Mendel in pea plant were

1. 1
2. 2
3. 3
4. 4

Question-45. The distance between the genes is measured by

1. angstrom
2. map unit
3. Dobson unit
4. millimetre

Question-46. The inheritance of flower colour in Antirrhinum (dog flower) is an example of

1. incomplete dominance
2. co-dominance
3. multiple alleles
4. linkage.

Question-47. To determine the genotype of a tall plant of F2 generation, Mendel crossed this plant with a dwarf plant. This cross represents a

1. test cross
2. back cross
3. reciprocal cross
4. dihybrid cross.

Question-48. Two or more independent genes present on different chromosomes which determine nearly same phenotype are called

1. supplementary genes
2. complementary genes
3. duplicate genes
4. none of these.

Question-49. What can be the blood group of offspring when both parents have AB blood group ?

1. AB only
2. A, B and AB
3. A, B, AB and O
4. A and B only

Question-50. What is the probability of production of dwarf offsprings in a cross betweeen two heterozygous tall pea plants ?

1. Zero
2. 50%
3. 25%
4. 100%

Question-51. What is true about the crossing over between linked genes ?

1. No crossing over at all
2. High percentage of crossing over
3. Hardly any crossing over
4. None of these

Question-52. What will be the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus ?

1. 3 : 1
2. 1 : 2 : 1
3. 1 : 1
4. None of these

Question-53. Which of the following are reasons for Mendel’s success ?(i) Usage of pure lines or pure breeding varieties(ii) Consideration of one character at a time(iii) Maintenance of statistical records of experiments(iv) Knowledge of linkage and incomplete dominance

1. (i) and (ii) only
2. (i), (ii) and (iii)
3. (i) and (iv) only
4. (ii), (iii) and (iv)

Question-54. Which of the following characters was not chosen by Mendel ?

1. Pod shape
2. Pod colour
3. Location of flower
4. Location of pod

Question-55. Which of the following is correct for the condition when plant YyRr is back crossed with the double recessive parent ?

1. 9 : 3 : 3 : 1 ratio of phenotypes only
2. 9 : 3 : 3 : 1 ratio of genotypes only
3. 1 : 1 : 1 : 1 ratio of phenotypes only
4. 1 : 1 : 1 : 1 ratio of phenotypes and genotypes

Question-56. Which of the following is incorrect regarding ZW – ZZ type of sex determination ?

1. It occurs in birds and some reptiles.
2. Females are homogametic and males are heterogametic.
3. 1:1 sex ratio is produced in the offsprings.
4. All of these

Question-57. Which of the following is suitable for experiment on linkage ?

1. aaBB x aaBB
2. AABB x aabb
3. AaBb x AaBb
4. AAbb x AaBB

Question-58. Which of the following trait is controlled by dominant autosomal genes ?

1. Polydactyly
2. Huntington’s chorea
3. PTC (phenylthiocarbamide) tasting
4. All of these

Question-59. Which of the following will not result in variations among siblings ?

1. Independent assortment of genes
2. Crossing over
3. Linkage
4. Mutation

Question-60. Which three scientists independently rediscovered Mendel’s work ?

1. Avery, McLeod, McCarty
2. Sutton, Morgan and Bridges
3. Bateson, Punnet and Bridges
4. de Vries, Correns and Tschemark

Question-61. XO type of sex determination and XY type of sex determination are the examples of

1. male heterogamety
2. female heterogamety
3. male homogamety
4. both (b) and (c)

Question-62. ZZ/ZW type of sex determination is seen in

1. platypus
2. snails
3. cockroach
4. peacock