Chromosomal Basis of Inheritance
Multiple Choice Questions and Answers
1. As a result of incomplete dominance cross between blue and white and Andalusian fowls produce
(a) 25% black, 75% white fowls
(b) 50% blue, 50% black fowls
(c) 50% blue 50% white fowls
(d) 25% blue 75% white fowls
Answer: (c) 50% blue 50% white fowls
2. When a single gene influences more than one trait it is called
(a) epistasis
(b) pseudodominance
(c) pleiotropy
(d) none of these
Answer: (c) pleiotropy
3. Under what conditions F2 ratio of 9:7 is obtained
(a) co-dominance
(b) suppressor genes
(c) duplicate genes
(d) complementary genes
Answer: (d) complementary genes
4. In a dihybrid cross, F2 progeny from the cross AABB and aabb the genotypes AABB, AABb, AaBB and aabb will be found in the ratio
(a) 9:3:3:1
(b) 3:3:1:1
(c) 1:2:2:1
(d) 1:1:1:1
Answer: (c) 1:2:2:1
5. A cell is heterozygous for three gene loci. How many different types of gametes can it form?
(a) 2
(b) 3
(c) 8
(d) 6
Answer: (b) 3
6. Which of the following statements is not true?
(a) polygenic character is controlled by multiple alleles
(b) in case of polygenic inheritance thousands of intermediate phenotypes are found between two extremes
(c) height, weight and skin colour are polygenic
(d) polygenic character is controlled by multiple genes
Answer: (a) polygenic character is controlled by multiple alleles
7. In monohybrid cross, two heterozygous F1 individuals were crossed and phenotypic ratio comes out to be 2:1.It was due to
(a) dominant lethal genes in homozygous individuals
(b) dominant lethal genes in a heterozygous individuals
(c) dominant epistasis
(d) none of the above
Answer: (a) dominant lethal genes in homozygous individuals
8. In co-dominance F1 hybrid show
(a) both dominant and recessive characters
(b) only dominant character
(c) only recessive character
(d) intermediate character between dominant and recessive
Answer: (a) both dominant and recessive characters
9. In a dihybrid cross, if F1 individuals are self crossed, phenotypic ratio comes to be 15:1. It is due to
(a) duplicate genes
(b) supplementary genes
(c) dominant epistasis
(d) recessive epistasis
Answer: (a) duplicate genes
10. How many types of gametes does a monoallelic heterozygous plant produce?
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (b) 2
11. In polygenic inheritance the familiar phenotypic dihybrid ratio of 9:3:3:1 is modified to
(a) 1:4:6:4:1
(b) 2:3:6:3:2
(c) 1:2:2:4:1:2:1:2:1
(d) 1:3:6:3:2:1
Answer: (c) 1:2:2:4:1:2:1:2:1
12. The phenomenon in which an allele of one gene suppresses the activity of an allele of another gene is known as
(a) inactivation
(b) dominance
(c) epistasis
(d) suppression
Answer: (c) epistasis
13. Epistasis was discovered by
(a) Shull
(b) Johanssen
(c) Mendel
(d) Bateson
Answer: (a) Shull
14. In sweet pea, both dominant genes C and P are essential for the development of purple colour. What would be the ratio of plants producing different colours in the progeny of cross CcPp x CcPp?
(a) 2 white and 6 purple coloured flowers
(b) 2 Purple and 6 white coloured flowers
(c) 3 white and 5 purple coloured flowers
(d) 3 purple and 5 white coloured flowers
Answer: (d) 3 purple and 5 white coloured flowers
15. Red (RR) Antirrhinum is crossed with white (ww) one. Offsprings Rw are pink. This is an example of
(a) dominant-recessive
(b) incomplete dominance
(c) hybrid
(d) supplementary genes
Answer: (b) incomplete dominance
16. In a genetic cross having recessive epistasis, F2 phenotypic ratio would be
(a) 9:6:1
(b) 15:1
(c) 9:3:4
(d) 12:3:1
Answer: (c) 9:3:4
17. When red and white flowered Mirabilis are crossed, pink hybrids occur in F1 generation. If this pink hybrid is then crossed with the white, the phenotypic ratios among the progeny would be
(a) 1 pink: 3 white
(b) 3 pink: 1 white
(c) 1 pink: 1 white
(d) 1 red : pink: 1 white
Answer: (c) 1 pink: 1 white
18. When walnut combed chicken were crossed with single combed chicken, only walnut combed chicken were obtained in F1. The genotypes of the parents was
(a) RrPp × rrpp
(b) RRPP × rrpp
(c) RRpp × rrpp
(d) RRPp × rrpp
Answer: (b) RRPP × rrpp
19. Mice coat colour may be either coloured (C), agouti (A) or albino (c and a). Two mice with agouti (CcAa) colour where crossed. If coloured phenotype is recessive to agouti, what ratios would be obtained?
(a) 12 agouti:3 coloured:1 albino
(b) 12 coloured: 3 agouti: 4 albino
(c) 9 coloured: 3 agouti:4 albino
(d) 9 agouti: 3 coloured:4 albino
Answer: (d) 9 agouti: 3 coloured:4 albino
20. Two summer white squashes with genotype WwYy were crossed (Week= white colour, Y=yellow colour, w and y= green colour) W is epistatic to Y and y. What would be the different colours of summer squashes obtained out of the above cross?
(a) 12 white: 3 yellow:1 green
(b) 12 yellow: 3 white: 1 green
(c) 12 green: 1 white: 3 yellow
(d) 12 yellow: 3 green: 1 white
Answer: (a) 12 white: 3 yellow:1 green
21. The production of two different types of capsules in Shepherd’s purse is the result of
(a) dominant epistasis
(b) duplicate dominant epistasis
(c) lethality
(d) complementary genes
Answer: (b) duplicate dominant epistasis
22. Both the dominant and recessive interactions are shown by
(a) comb shapes in poultry
(b) flower colour in sweet pea
(c) leaf colour in rice
(d) endosperm of maize
Answer: (c) leaf colour in rice
23. In rice aaBB and aaBb produce purple leaves, while a gene were ever present inhibits formation of purple colour which is developed by gene B. What should be the F2 ratio arising out of selling of plants with genotype AaBb?
(a) all purple leaved
(b) all green leaved
(c) 15 purple leaved :1 green leaved
(d) 13 green leaved : 3 purple leaved
Answer: (d) 13 green leaved : 3 purple leaved
24. In case of incomplete dominance in F2 generation
(a) genotype ratio 3 : 1
(b) phenotypic ratio is 3 :1
(c) genotypic ratio = phenotypic ratio
(d) nothing can be concluded
Answer: (c) genotypic ratio = phenotypic ratio
25. The phenomenon in which an allele of one gene suppresses the activity of an allele of another gene is known as
(a) dominance
(b) inactivation
(c) epistasis
(d) suppression
Answer: (c) epistasis
26. A gene which affects the character of another gene not located on similar locus of the homologous chromosomes is
(a) duplicate gene
(b) complementary gene
(c) supplementary gene
(d) epistatic gene
Answer: (b) complementary gene
27. When an albino 4 o’clock plant is crossed with a normal green plant (male), all plants in the progeny are albino because
(a) albinism is dominant over green
(b) plastids are inherited through maternal cytoplasm
(c) plastids of male parents become mutated
(d) crossing over results in structural changes in plastids
Answer: (b) plastids are inherited through maternal cytoplasm
28. In case of interaction with two dominant genes are similar in their individual effects but both are essential to produce a different phenotype, then the genes are known as
(a) complementary genes
(b) supplementary genes
(c) epistatic genes
(d) hypostatic genes
Answer: (a) complementary genes
29. The epistatic dominant inhibitor gene modifies the 9: 3 : 1 ratio to
(a) 9:3:4
(b) 9:6:1
(c) 12:3:1
(d) 9:7
Answer: (d) 9:7
30. A gene at one locus is said to be epistatic to a second gene at another locus when
(a) the gene at the first locus masks the phenotypic expression of the second gene
(b) the gene at the first locus acts independent of the second gene
(c) the gene at the first locus assumes the functions of the second gene
(d) none of the above
Answer: (c) the gene at the first locus assumes the functions of the second gene
31. In Lathyrus odoratus the cross between two purple flowered plants gave a pink flowered progeny. This is due to
(a) incomplete dominance
(b) codominance
(c) epistasis
(d) segregation
Answer: (c) epistasis
32. In a second filial generation 9 :3 :3:1 ratio is replaced by 9 : 7 ratio, it is due to
(a) complementary gene
(b) epistatic gene
(c) supplementary gene
(d) hypostatic gene
Answer: (a) complementary gene
33. In Mirabilis jalapa, when homozygous red flower and white flowered plants are crossed, all F1 plants have ink coloured flowers. In F2, produced by selfing of F1 plants, red, pink and white coloured flower plants would appear respectively in
(a) 1:2:1
(b) 2:1:1
(c) 1:0:1
(d) 1:2:1
Answer: (d) 1:2:1
34. A gene pair hides the effects of another gene. The phenomenon is called
(a) epistasis
(b) mutation
(c) dominant
(d) segregation
Answer: (a) epistasis
35. Sickle cell anaemia is
(a) sex linked inheritance
(b) autosomal heritable disease
(c) infectious disease
(d) deficiency disease
Answer: (b) autosomal heritable disease
36. Pleiotropic effect is found in
(a) human skin colour
(b) night blindnes
(c) haemophilia
(d) sickle cell anaemia
Answer: (d) sickle cell anaemia
37. Which one is incorrect?
(a) Polygenic character is controlled by multiple genes
(b) Numerous intermediate types are found in between the two extremes in polygenic inheritance
(c) height weight and skin colour are polygenic
(d) polygenic trait is controlled by multiple alleles
Answer: (d) polygenic trait is controlled by multiple alleles
38. B-blood group man marries A blood group woman. The first child has B blood group. Genotype of the child is
(a) lA lO
(b) lB lO
(c) lA lB
(d) lB lB
Answer: (b) lB lO
39. Which pair of features represents polygenic inheritance?
(a) human eye colour and sickle cell anaemia
(b) hair pigment of mouth and tongue rolling in humans
(c) ABO blood group in humans and flower colour of Mirabilis jalapa
(d) human height and skin colour
Answer: (d) human height and skin colour
40. Which one shows complementary gene interaction ratio of 9:7?
(a) 4 o’clock plant
(b) feather colour in Fowl
(c) flower colour in sweet pea
(d) coat colour in mouse
Answer: (b) Feather colour in Fowl
41. The graphical representation to calculate the probability of all possible genotypes of offspring in a genetic cross is called
(a) Pedigree analysis
(b) Punnet square
(c) Chromosome map
(d) Genotypic ratio
Answer: (b) Punnet square
42. Snapdragon is also an example of
(a) incomplete dominance
(b) complete dominance
(c) co-dominance
(d) none of these
Answer: (a) incomplete dominance
43. F2 phenotypic ratio of 1 : 2 : 1 is obtained in
(a) complete dominance
(b) incomplete dominance
(c) co-dominance
(d) none of these
Answer: (b) incomplete dominance
44. Interaction between genes on same or on different chromosomes controlling a ………. character is called inter-allelic.
(a) single
(b) double
(c) both a and b
(d) none
Answer: (a) single
45. In incomplete dominance F2 genotypic ratio is
(a) 1:2:1
(b) 2:1:1
(c) 2:2:2
(d) none
Answer: (a) 1:2:1
46. …….ratio is obtained when homozygous dominant condition is lethal
(a) 2:1
(b) 3:1
(c) 4:1
(d) 1:1
Answer: (a) 2:1
47. ……… colour of summer squash is an example of dominant epistasis.
(a) Flower
(b) Leaf
(c) Fruit
(d) None
Answer: (c) Fruit
48. Pigment colour in flour moth is
(a) maternal effect
(b) paternal effect
(c) both
(d) none
Answer: (a) maternal effect
49. Name the phenomenon shown by Mirabilis jalapa
(a) incomplete dominance
(b) complete dominance
(c) co-dominance
(d) none of these
Answer: (a) incomplete dominance
50. Which of the following statements is true?
(a) In Lathyrus odoratus, two dominant genes are necessary for the flower colour
(b) In poultry, comb the shape is controlled by two gene pairs
(c) both a and b
(d) none
Answer: (c) both a and b