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

Question: Which of the following condition is called monosomics
a) 2n+1
b) 2n+2
c) 2n-1
d) n+1
Answer: c

Question: An organism with two identical alleles is
a) dominant
b) hybrid
c) heterozygous
d) homozygous
Answer: d

Question: In Antirrhinum two plants with pink flowers were hybridized. The F1 plants produced red, pink and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridisation?
a) rrrr
b) RR
c) Rr
d) rr
Answer: c

Question: A human male produces sperms with the genotypes AB, Ab, aB and ab pertaining to two diallelic characters in equal proportions. What is the corresponding genotype of this person?
a) AaBB
b) AABb
c) AABB
d) AaBb
Answer: d

Question: 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: d

Question: F2 generation in a Mendelian cross showed that both genotypic and phenotypic ratios are same as 1 : 2 : 1. It represents a case of
a) co-dominance
b) dihybrid cross
c) monohybrid cross with complete dominance
d) monohybrid cross with incomplete dominance
Answer: d

Question: In human beings 45 chromosomes/single X/XO abnormality causes
a) Down’s syndrome
b) Kinefelter’s syndrome
c) Turner’s syndrome
d) Edward’s syndrome
Answer: c

Question: Multiple alleles are present
a) at the same locus of the chromosome
b) on non-sister chromatids
c) on different chromosomes
d) at different loci on the same chromosome
Answer: a

Question: Mendel’s last law is
a) segregation
b) dominance
c) independent assortment
d) polygenic inheritance
Answer: c

Question: When two unrelated individuals or lines are crossed, the performance of F1 hybrid is often superior to both its parents. This phenomenon is called
a) heterosis
b) transformation
c) splicing
d) metamorphosis
Answer: a

Question: tt mates with Tt. What will be characteristic of offspring?
a) 75% recessive
b) 50% recessive
c) 25% recessive
d) All dominant
Answer: b

Question: 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

Question: Experimental verification of the chromosomal theory of inheritance was done by
a) Mendel
b) Sutton
c) Boveri
d) Morgan
Answer: d

Question: The genotype of a plant showing the dominant phenotype can be determined by
a) test cross
b) dihybrid cross
c) pedigree analysis
d) back cross
Answer: a

Question: A child’s blood group is ‘O’. The parent’s blood groups cannot be
a) A and B
b) A and A
c) AB and O
d) B and O
Answer: c

Question: In a test cross involving F1 dihybrid flies, more parental-type offspring were produced than the recombinant-type offspring. This indicates
a) the two genes are linked and present on the same chromosome
b) both of the characters are controlled by more than one gene
c) the two genes are located on two different chromosomes
d) chromosomes failed to separate during meiosis
Answer: a

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
Answer: c

Question: An abnormal human male phenotype involving an extra X-chromosome (XXY) is a case of
a) Edward’s syndrome
b) Klinefelter’s syndrome
c) intersex
d) Down’s syndrome
Answer: b

Question: Male XX and female XY sometime occur due to
a) deletion
b) transfer of segments in X and Y chromosome
c) aneuploidy
d) hormonal imbalance
Answer: b

Question: Which of the following is suitable for experiment on linkage?
a) aaBB × aaBB
b) AABB × aabb
c) AaBb × AaBb
d) AAbb × AaBB
Answer: b

Question: Thalassemia and sickle cell anaemia are caused due to a problem in globin molecule synthesis. Select the correct statement.
a) Both are due to a quantitative defect in globin chain synthesis.
b) Thalassemia is due to less synthesis of globin molecules.
c) Sickle cell anaemia is due to a quantitative problem of globin molecules.
d) Both are due to a qualitative defect in globin chain synthesis.
Answer: b

Question: In order to find out the different types of gametes produced by a pea plant having the genotype AaBb it should be crossed to a plant with the genotype
a) AABB
b) AaBb
c) aabb
d) aaBB
Answer: c

Question: When a single gene influences more than one trait it is called
a) pseudodominance
b) pleiotropy
c) epistasis
d) None of the options
Answer: b

Question: Down’s syndrome in humans is due to
a) three ‘X’ chromosomes
b) three copies of chromosome 21
c) monosomy
d) two ‘Y’ chromosomes
Answer: b

Question: A diseased man marries a normal woman. They get three daughters and five sons. All the daughters were diseased and sons were normal. The gene of this disease is
a) sex linked dominant
b) sex linked recessive
c) sex limited character
d) autosomal dominant
Answer: a

Question: A fruit fly is heterozygous for sex-linked genes, when mated with normal female fruit fly, the males specific chromosome will enter egg cell in the proportion
a) 3 : 1
b) 7 : 1
c) 1 : 1
d) 2 : 1
Answer: c

Question: A normal green male maize is crossed with albino female. The progeny is albino because
a) trait for albinism is dominant
b) the albinos have biochemical to destroy plastids derived from green male
c) plastids are inherited from female parent
d) green plastids of male must have mutated
Answer: c

Question: Which one is a hereditary disease?
a) Cataract
b) Leprosy
c) Blindness
d) Phenylketonuria
Answer: d

Question: Two non-allelic genes produces the new phenotype when present together but fail to do so independently then it is called
a) epistasis
b) polygene
c) non complementary gene
d) complementary gene
Answer: a

Question: Segregation of Mendelian factors (no linkage, no crossing over) occurs during
a) anaphase I
b) anaphase II
c) diplotene
d) metaphase I
Answer: a

Question: A man and a woman, who do not show any apparent signs of a certain inherited disease, have seven children (2 daughters and 5 sons). Three of the sons suffer from the given disease but none of the daughters affected. Which of the following mode of inheritance do you suggest for this disease?
a) Sex-linked dominant
b) Sex-linked recessive
c) Sex-limited recessive
d) Autosomal dominant
Answer: b

Question: Select the incorrect statement from the following.
a) Galactosemia is an inborn error of metabolism.
b) Small population size results in random genetic drift in a population.
c) Baldness is a sex-limited trait.
d) Linkage is an exception to the principle of independent assortment in heredity.
Answer: c

Question: A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. What is the probability of their grandson being colour blind ?
a) Nil
b) 0.25
c) 0.5
d) 1
Answer: b