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.
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.
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
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.
Q.5. Inheritance of skin colour in humans is an example on
(a) point mutation
(b) polygenic inheritance
(d) chromosomal aberration.
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.
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
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
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
Q.10. If a plant heterozygous for tallness is selfed, the F2 generation has both tall and dwarf plants. It proves the principle of
(c) independent assortment
(d) incomplete dominance
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
Q.12. Person having genotype IA IB would show the blood group as AB. This is because of
(d) incomplete dominance
Q.13. Conditions of a karyotype 2n + 1, 2n – 1 and 2n + 2, 2n – 2 are called
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
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.
Q.16. ZZ/ZW type of sex determination is seen in
Q.17. Which of the following will not result in variations among siblings?
(a) Independent assortment of genes
(b) Crossing over
Q.18. What will never be father’s blood group if the mother has blood group B and child blood
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
Q.20. Occasionally, a single gene may express more than one effect. The phenomenon is called
(a) multiple allelism
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
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
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.
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
Q.25. Which of the following represents a pair of contrasting characters?
(a) Allele (or allelomorphs)
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