MCQ Questions for Class 12 Biology Chapter 5 Principle of inheritance and variation

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MCQ Questions for Class 12 Biology Chapter 5 Principle of inheritance and variation

Q.1. Test cross involves
(a) crossing between two genotypes with dominant trait
(b) crossing between two genotypes with recessive trait
(c) crossing between two F1 hybrids
(d) crossing the F1 hybrid with a double recessive genotype.

Answer Answer: (d)

Q.2. 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.

Answer Answer: (a)

Q.3. If a colour blind woman marries a normal visioned man, their sons will be
(a) all colour blind
(b) all normal visioned
(c) one-half colour blind and one-half normal
(d) three-fourths colour blind and one-fourth normal

Answer Answer: (a)

Q.4. 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 honey bee.
(d) Pod shape in garden pea.

Answer Answer: (a)

Q.5. Inheritance of skin colour in humans is an example on
(a) point mutation
(b) polygenic inheritance
(c) codominance
(d) chromosomal aberration.

Answer Answer: (b)

Q.6. Study the pedigree chart given below. What does it show?
(a) Inheritance of a condition like phenylketonuria as an autosomal recessive trait.
(b) The pedigree chart is wrong as this is not possible.
(c) Inheritance of a recessive sex-linked disease like haemophilia.
(d) Inheritance of a sex-linked inborn error of metabolism like phenylketonuria.

Answer Answer: (a)

Q.7. All genes located on the same chromosome
(a) form different groups depending upon their relative distance
(b) form one linkage group
(c) will not from any linkage groups
(d) form interactive groups that affect the phenotype

Answer Answer: (b)

Q.8. Distance between the genes and percentage of recombination shows
(a) a direct relationship
(b) an inverse relationship
(c) a parallel relationship
(d) no relationship

Answer Answer: (a)

Q.9. If a genetic disease is transferred from a phenotypically normal but carrier female to only
some of the male progeny, the disease is

(a) autosomal dominant
(b) autosomal recessive
(c) sex-linked dominant
(d) sex-linked recessive

Answer Answer: (d)

Q.10. If a plant heterozygous for tallness is selfed, the F2 generation has both tall and dwarf plants. It proves the principle of
(a) dominance
(b) segregation
(c) independent assortment
(d) incomplete dominance

Answer Answer: (b)

Q.11. In sickle cell anaemia glutamic acid is replaced by valine. Which one of the following triplets codes for valine?
(a) G G G
(b) A A G
(c) G A A
(d) G U G

Answer Answer: (d)

Q.12. Person having genotype IA IB would show the blood group as AB. This is because of
(a) pleiotropy
(b) co-dominance
(c) segregation
(d) incomplete dominance

Answer Answer: (b)

Q.13. Conditions of a karyotype 2n + 1, 2n – 1 and 2n + 2, 2n – 2 are called
(a) aneuploidy
(b) polyploidy
(c) allopolyploidy
(d) monosomy

Answer Answer: (a)

Q.14. A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents?
(a) TT and Tt
(b) Tt and Tt
(c) TT and TT
(d) Tt and tt

Answer Answer: (b)

Q.15. In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that
(a) the alleles of two genes are interacting with each other
(b) it is a multigenic inheritance
(c) it is a case of multiple allelism
(d) the alleles of two genes are segregating independently.

Answer Answer: (d)

Q.16. ZZ/ZW type of sex determination is seen in
(a) platypus
(b) snails
(c) cockroach
(d) peacock

Answer Answer: (d)

Q.17. Which of the following will not result in variations among siblings?
(a) Independent assortment of genes
(b) Crossing over
(c) Linkage
(d) Mutation

Answer Answer: (c)

Q.18. What will never be father’s blood group if the mother has blood group B and child blood
group O?

(a) A
(b) B
(c) AB
(d) O

Answer Answer: (c)

Q.19. Mendel’s Law of independent assortment holds good for genes situated on the
(a) non-homologous chromosomes
(b) homologous chromosomes
(c) extra nuclear genetic element
(d) same chromosome

Answer Answer: (b)

Q.20. Occasionally, a single gene may express more than one effect. The phenomenon is called
(a) multiple allelism
(b) mosaicism
(c) pleiotropy
(d) polygeny

Answer Answer: (c)

Q.21. In a certain taxon of insects some have 17 chromosomes and the others have 18 chromosomes. The 17 and 18 chromosome bearing organisms are
(a) males and females, respectively
(b) females and males, respectively
(c) all males
(d) all females

Answer Answer: (a)

Q.22. The inheritance pattern of a gene over generations among humans is studied by the pedigree analysis. Character studied in the pedigree analysis is equivalent to
(a) quantitative trait
(b) Mendelian trait
(c) polygenic trait
(d) maternal trait

Answer Answer: (b)

Q.23. It is said that Mendel proposed that the factor controlling any character is discrete and
independent. His proposition was based on the

(a) results of F3 generation of a cross.
(b) observations that the offspring of a cross made between the plants having two contrasting
characters shows only one character without any blending.
(c) self pollination of F1 offsprings.
(d) cross pollination of F1 generation with recessive parent.

Answer Answer: (b)

Q.24. In the F2 generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are
(a) phenotypes – 4; genotypes – 16
(b) phenotypes – 9; genotypes – 4
(c) phenotypes – 4; genotypes – 8
(d) phenotypes – 4; genotypes – 9

Answer Answer: (d)

Q.25. Which of the following represents a pair of contrasting characters?
(a) Allele (or allelomorphs)
(b) Phenotype
(c) Homozygous
(d) Heterozygous

Answer Answer: (a)

Q.26. Two genes ‘A’ and ‘B’ are linked. In a dihybrid cross involving these two genes, the F1
heterozygote is crossed with homozygous recessive parental type (aa bb). What would be the
ratio of offspring in the next generation?

(a) 1 : 1 : 1: 1
(b) 9 : 3 : 3 : 1
(c) 3 : 1
(d) 1 : 1

Answer Answer: (d)

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