Class 12 topic wise Online MCQ with answers
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3. Inheritance and Variation
1. Thalassemia and sickle cell
anemia 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 anemia is due to a quantitative problem of globin
molecules.
(d) Both are due to a qualitative defect in globin chain synthesis.
Answer :- (b) Thalassemia is due to less synthesis of globin molecules.
2. The genotypes of a husband
and wife are I A I B and I A i . Among
the blood types of their children, how many different
genotypes and phenotypes are possible?
(a) 3 genotypes; 4 phenotypes
(b) 4 genotypes; 3 phenotypes
(c) 4 genotypes; 4 phenotypes
(d) 3 genotypes; 3 phenotypes
Answer :- (b) 4 genotypes; 3 phenotypes
3. A disease caused by an
autosomal primary nondisjunction is
(a) Klinefelter’s syndrome
(b) Turner’s syndrome
(c) sickle cell anemia
(d) Down’s syndrome.
Answer :- (d) Down’s syndrome.
4. 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
5. Which one from those given
below is the period for Mendel’s hybridization experiments?
(a) 1840-1850
(b) 1857-1869
(c) 1870-1877
(d) 1856-1863
6. The mechanism that causes a
gene to move from one linkage group to another is called
(a) inversion
(b) duplication
(c) translocation
(d) crossing over.
7. If a colorblind man marries
a woman who is homozygous for normal color vision, the probability of their son
being colorblind is
(a) 0
(b) 0.5
(c) 0.75
(d) 1.
8. A cell at telophase stage
is observed by a student in a plant brought from the field. He tells his
teacher that this cell is not like other
cells at telophase stage. There is no formation of cell plate and thus the cell
is containing more number of chromosomes as compared to other dividing
cells. This would result in
(a) soma clonal variation
(b) polytony
(c) aneuploidy
(d) polyploidy.
9. Pick out the correct
statements.
(1) Hemophilia is a sex-linked recessive disease.
(2) Down’s syndrome is due to aneuploidy.
(3) Phenylketonuria is an autosomal recessive gene disorder.
(4) Sickle cell anemia is an X linked recessive gene disorder.
(a) (1), (3) and (4) are correct.
(b) (1), (2) and (3) are correct.
(c) (1) and (4) are correct.
(d) (2) and (4) are correct.
10. A tall true breeding
garden pea plant is crossed with a dwarf true breeding garden pea plant. When
the F 1 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.
11. If both parents are
carriers for thalassemia, which is an autosomal recessive disorder, what are
the chances of pregnancy resulting in an
affected child?
(a) 25%
(b) 100%
(c) No chance
(d) 50%
12. In a test cross involving
F 1 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.
13. Which of the following
most appropriately describes hemophilia?
(a) Chromosomal disorder
(b) Dominant gene disorder
(c) Recessive gene disorder
(d) X Linked recessive gene disorder
14. A gene showing codominance
has
(a) alleles that are recessive to each other
(b) both alleles independently expressed in the heterozygote
(c) one allele dominant on the other
(d) alleles tightly linked on the same chromosome.
15. In his classic experiments
on pea plants, Mendel did not use
(a) seed
shape
(b) flower
position
(c) seed
colour
(d) pod length.
16. A color 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
17. A pleiotropic gene
(a) controls a trait only in combination with another gene
(b) controls multiple traits in an individual
(c) is expressed only in primitive plants
(d) is a gene evolved during Pliocene.
18. The term “linkage” was
coined by
(a) G. Mendel
(b) W. Sutton
(c) T.H.
Morgan
(d) T.
Boveri. (2015)
19. The movement of a gene
from one linkage group to another is called
(a) translocation
(b) crossing over
(c) inversion
(d) duplication.
20. Alleles are
(a) different molecular forms of a gene
(b) heterozygotes
(c) different phenotype
(d) true breeding homozygotes.
21. 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.
22. A man with blood group ‘A’
marries a woman with blood group ‘B’. What are all the possible blood groups of their off-springs?
(a) A, B, AB and O
(b) O only
(c) A and B only
(d) A, B and AB only
23. How many pairs of
contrasting characters in pea plants were studied by Mendel in his experiments?
(a) Eight
(b) Seven
(c) Five
(d) Six
24. An abnormal human baby
with ‘XXX’ sex chromosomes was born due to
(a) fusion of two ova and one sperm
(b) fusion of two sperms and one ovum
(c) formation of abnormal sperms in the father
(d) formation of abnormal ova in the mother.
25.
A human female with Turner’s syndrome
(a)
has 45 chromosomes with XO
(b)
has one additional X chromosome
(c)
exhibits male characters
(d)
is able to produce children with normal
husband.
26.Select the incorrect
statement with regard to haemophilia.
(a)
It is a dominant disease.
(b)
A single protein involved in the clotting of
blood is affected.
(c)
It is a sexlinked disease.
(d)
It is a recessive disease
27.
Which of the following cannot be detected in a
developing foetus by amniocentesis?
(a)
Down’s syndrome
(b) Jaundice
(c)
Klinefelter’s syndrome
(d) Sex of the fetus
28.
Down’s syndrome in humans is due to………………..
(a)
three ‘X’ chromosomes
(b)
three copies of chromosome 21
(c)
monosomy
(d)
two ‘Y’ chromosomes.
29.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
30.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.
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