CBSE Class 12 Biology Principles of Inheritance and Variation MCQs Set 07

Question: Among the following characters, which one was not considered by Mendel in his experiments on pea?
a) Trichomes–Glandular or non-glandular
b) Seed–Green or yellow
c) Pod–Inflated or constricted
d) Stem–Tall or dwarf
Answer: a

Question: How many types of gametes will be produced by individuals of AABbcc genotype?
a) Two
b) Four
c) Six
d) Nine
Answer: a

Question: If the DNA codons are ATG ATG ATG and a cytosine base is inserted at the beginning, which of the following will result?
a) CATGATGATG
b) CAT GAT GAT G
c) CATGATGATG
d) a nonsense mutation
Answer: b

Question: In sweet pea, the epistatic interaction between the genes for purple and white colour produced the two colours in the ratio –
a) 3:1
b) 8:8
c) 9:3:3:1
d) 9:7
Answer: d

Question: Which one of the following cannot be explained on the basis of Mendel’s Law of Dominance?
a) The discrete unit controlling a particular character is called a factor.
b) Out of one pair of factors one is dominant, and the other recessive.
c) Alleles do not show any blending and both the characters recover as such in F2 generation.
d) Factors occur in pairs.
Answer: c

Question: ABO blood groups is determined by
a) three recessive alleles
b) three codominant alleles
c) three alleles, two dominant and one recessive
d) three alleles, two recessive and one dominant
Answer: c

Question: In an organism, tall phenotype is dominant over recessive dwarf phenotype, and the alleles are designated as T and t, respectively. Upon crossing two different individuals, total 250 offsprings were obtained, out of which 124 displayed tall phenotype and rest were dwarf. Thus, the genotype of the parents were
a) TT × TT
b) TT × tt
c) Tt × Tt
d) Tt × tt
Answer: d

Question: A tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant. When the F1 plants were selfed the resulting genotypes were in the ratio of
a) 3 : 1 :: Tall : Dwarf
b) 3 : 1 :: Dwarf : Tall
c) 1 : 2 : 1 :: Tall homozygous : Tall heterozygous : Dwarf
d) 1 : 2 : 1 :: Tall heterozygous : Tall homozygous : Dwarf
Answer: c

Question: A cross between parents with AaBB and aaBB genotype will form –
a) all AaBB
b) 1 AaBB : 3 aaBB
c) 1 AaBB : 1 aaBB
d) 3 AaBB : 1 aaBB
Answer: c

Question: Substitution of a purine nucleotide by pyrimidine nucleotide is called
a) transition
b) transversion
c) inversion
d) transduction
Answer: a

Question: Which one of the following is a sex-linked disease?
a) Nightblindness
b) Glaucoma
c) Haemophilia
d) All of these
Answer: c

Question: A cross between hybrid and recessive parent is
a) back cross
b) test cross
c) monohybrid cross
d) dihybrid cross
Answer: b

Question: A child with mother of A group and father of AB group, will not have the following blood group –
a) A
b) B
c) AB
d) O
Answer: d

Question: Human skin colour is controlled by
a) a single allele
b) two alleles
c) at least three separate genes
d) four alleles
Answer: c

Question: In a red and white-flowered cross of Mirabilis jalapa, F2 generation has red, pink and white-flowered plants in the ratio of
a) 2 : 1 : 1
b) 1 : 1 : 2
c) 1 : 2 : 1
d) 1 : 0 : 1
Answer: c

Question: An allele is dominant, if it is expressed in –
a) second generation
b) homozygous combination
c) heterozygous combination
d) both homozygous and heterozygous conditions
Answer: d

Question: How many contrasting characters were selected by Mendel?
a) One
b) Two
c) Three
d) Seven
Answer: d

Question: A blue fowl obtained from mating between black and white fowls, is self-crossed. The F2 ratio is
a) 1 black : 2 white : 1 blue
b) 1 black : 2 blue : 1 white
c) 2 black : 1 white : 1 blue
d) none of these
Answer: b

Question: Chiasma represents the site of
a) homologous chromosome
b) crossing over
c) pachytene
d) diakinesis
Answer: b

Question: The combined form of coupling and repulsion is –
a) crossing over
b) mutation
c) linkage
d) disjunction
Answer: c

Question: Polygenes are
a) genes which control continuously variable characters like height, weight, etc.
b) multiple copies of a single gene
c) always linked genes
d) pseudogenes
Answer: a

Question: In Mendel’s experiments the alleles were
a) codominant
b) corecessive
c) dominant–recessive
d) incompletely dominant
Answer: c

Question: Which one of the following is the genotypic ratio in monohybrid cross?
a) 9 : 3 : 3 : 1
b) 1 : 2 : 1
c) 9 : 7
d) 3 : 1
Answer: b

Question: A woman with one gene for haemophilia and a gene for colour blindness on one of X chromosomes marries a normal man. How will the progeny be?
a) All sons and daughters haemophilic and colour blind
b) 50% haemophilic colour blind sons and 50% normal sons
c) 50% haemophilic daughters and 50% colour blind daughters
d) Haemophilic and colour blind daughters
Answer: b

Question: Gene located on the same locus but having different expressions are
a) oncogenes
b) polygenes
c) multiple alleles
d) codominants
Answer: c

Question: Two dominant independently assorting genes react with each other. They are
a) supplementary
b) complementary
c) duplicate
d) collaborative
Answer: b

Question: How many types of gametes will be produced by individuals having genotype AaBbCc?
a) Two
b) Four
c) Six
d) Eight
Answer: d

Question: Mendel’s monohybrid ratio is –
a) 1 : 2
b) 3 : 1
c) 9 : 3 : 3 : 1
d) 9 : 7
Answer: b

Question: The phenotypic and genotypic ratios remain same in F2 generation in case of
a) dihybrid cross
b) supplementary genes
c) incomplete dominance
d) inhibitory genes
Answer: c

Question: A family of five daughters only is expecting sixth issue. The chance of its being son is
a) zero
b) 25%
c) 50%
d) 100%
Answer: c

Question: In keeping with the law of independent assortment what is actually assorted?
a) Different genes on the same chromosome
b) Centromeres
c) Homologous chromosomes
d) Heterologous chromosomes
Answer: c

Question: Imagine that in maize plant, the factors for controlling seed coat and seed shape are present on the same chromosome very close together. Performing dihybrid experiments with these characters, Mendel would not have been able to arrive at the idea of
a) Dominance
b) Independent assortment
c) Incomplete dominance
d) Segregation
Answer: b

Question: Crossing over in diploid organisms is responsible for
a) linkage between genes
b) segregation of alleles
c) dominance of genes
d) recombination of linked genes
Answer: d

Question: The meaning of syndrome is related to
a) dwarf organism
b) diseased condition
c) a group of symptoms
d) viral disease
Answer: c

Question: Chromosomal abberation is commonly found in
a) cancer cells
b) normal cells
c) healthy cells
d) autosomal cells
Answer: a

Question: Phenylketonuria is caused due to
a) pleiotropy
b) multiple alleles
c) codominance
d) incomplete dominance
Answer: a

Question: In XX and XY type of sex-determination,
a) males are heterogametic
b) females are isogametic
c) Both (a) and (b)
d) None of the option is correct
Answer: a

Question: The unfertilised eggs in honeybees develop into
a) males
b) queen
c) worker
d) Both (a) and (c)
Answer: a

Question: Choose the incorrect pair with respect to sex determination in different organisms.
a) Grasshopper = XO type
b) Birds = ZZ–ZW type
c) Drosophila = XX–XO type
d) Human = XX–XY type
Answer: c

Question: Polygenic traits are controlled by
a) one gene
b) two genes
c) three or more genes
d) mutant genes
Answer: c

Question: The figure depicts
a) Linkage
b) Independent assortment
c) Law of dominance
d) Equational division
Answer: b

Question: Phenylketonuria in humans
a) manifests through phenotypic expressions
b) is characterised by mental retardation
c) leads to hair reduction and skin pigmentation
d) All of the above
Answer: d

Question: Point mutation arises due to a change in
a) single base DNA
b) single base pair of DNA
c) segment of DNA
d) double base pair of DNA
Answer: b

Question: Both chromosome and gene are transmitted from generation to generation in
a) changed form
b) unaltered form
c) altered form
d) disintegrated form
Answer: b