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Principles of Inheritance and Variation Class 12 MCQs Questions with Answers
Solve this Principles of Inheritance and Variation Multiple Choice Questions of Class 12 Biology Chapter 5 MCQ, so as not to miss out on any concept from being clear about what they mean!
Select the correct answer
Question 1.
All genes located on the same chromosome:
(a) form different groups depending upon their relative distance
(b) form one linkage group
(c) will not form any linkage groups
(d) form interactive groups that affect the phenotype
Answer
Answer: (b) form one linkage group
Question 2.
Conditions of a karyotype 2n + 1 and 2n ± 2 are called:
(a) Aneuploidy
(b) Polyploidy
(c) Allopolyploidy
(d) Monosomy.
Answer
Answer: (a) Aneuploidy
Question 3.
Distance between the genes and advantage of recombination shows:
(a) a direct relationship
(b) an inverse relationship
(c) a parallel relationship
(d) no relationship.
Answer
Answer: (a) a direct relationship
Question 4.
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) Sex-linked recessive.
Question 5.
In sickle cell anaemia glutamic acid is replaced by valine. Which one of the following triplets codes for valine?
(a) GGG
(b) AAG
(c) GAA
(d) GUG.
Answer
Answer: (d) GUG.
Question 6.
Person having genotype lA lB would show the blood group as AB. This is because of:
(a) Pleiotropy
(b) Co-dominance
(c) Segregation
(d) Incomplete dominance.
Answer
Answer: (b) Co-dominance
Question 7.
ZZ / ZW type of sex determination is seen in :
(a) Platypus
(b) Snails
(c) Cockroach
(d) Peacock.
Answer
Answer: (d) Peacock.
Question 8.
A cross between two tall plants resulted in offspring having a 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) Tt and Tt
Question 9.
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 alleles m
(d) The alleles of two genes are segregating independently.
Answer
Answer: (d) The alleles of two genes are segregating independently.
Question 10.
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) Linkage
Question 11.
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: (a) non-homologous chromosomes
Question 12.
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) pleiotropy
Question 13.
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) males and females, respectively
Question 14.
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) Mendelian trait
Question 15.
It is said that Mendel proposed that the factor controlling any character is discrete and independent. This 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 parental generations.
Answer
Answer: (b) observations that the offspring of a cross made between the plants having two contrasting characters shows only one character without any blending.
Question 16.
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) 1 : 1
Question 17.
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) Phenotypes -4; genotypes -9.
Question 18.
Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood groups, respectively. What would be the genotype of both mother and father ?
(a) Mother is homozygous for ‘A’ blood group and father is heterozygous for ‘ B’.
(b) Mother is heterozygous for ‘A’ blood group and father is homozygous for ‘B’.
(c) Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively.
(d) Both mother and father are homozygous for ‘A’ and ‘B’ blood group, respectively.
Answer
Answer: (c) Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively.
Assertion and Reason Type Questions
These questions consist of two statements each, printed as Assertion and Reason.
While answering these questions you are required to choose any one of the following four responses.
(a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
(c) If Assertion is true but the Reason is false.
(d) If both Assertion and Reason are false.
Question 19.
Assertion: In humans the gamete contributed by male determines whether the child produced will be male or female.
Reason: Sex in humans is polygenic trait depending upon a cumulative effect of some genes on X-chromosome and some on Y-chromosome.
Answer
Answer: (c) If Assertion is true but the Reason is false.
Question 20.
Assertion: Progeny of pure line is heterozygous.
Reason: Pure lines are not the progeny of homozygous organisms.
Answer
Answer: (d) If both Assertion and Reason are false.
Question 21.
Assertion: Extranuclear chromosomes are present in mitochondria and plastids.
Reason: They are prochromosomes or organelle chromosomes.
Answer
Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
Question 22.
Assertion: Mendel formulated the laws of heredity.
Reason: Mendel did not perform the study of one character at a time.
Answer
Answer: (c) If Assertion is true but the Reason is false.
Question 23.
Assertion: Over-exposure to sun tans the skin in human beings.
Reason: Melanin appears in the epidermal cells which saves the skin from UV rays of sun.
Answer
Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
Question 24.
Assertion: Y chromosomes are called androsome.
Reason: X and Y chromosomes differ in form and size.
Answer
Answer: (b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
Question 25.
Assertion: DNA is a long, double stranded and linear in eukaryotic chromosome.
Reason: The eukaryotic chromosomes are composed of DNA, proteins, RNA, metal ions and enzymes.
Answer
Answer: (b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
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