Genetics MCQs Part I

1) The hereditary material in the tobacco mosaic virus is
a) DNA
b) RNA
c) Both DNA and RNA
d) None of these

2) DNA is the genetic material because it
a) Controls metabolism
b) Replicates
c) Mutates
d) All the above

3) Information for growth , metabolism and reproduction lies in
a) Proteins
b) Polysaccharides
c) DNA
d) RNA

4) The pyrimidines present in the DNA molecule are
a) Adenine and thymine
b) Guanine and cytosine
c) Thymine and cytosine
d) Adenine and guanine

5) Which one of the following replaces the uracil of RNA molecule in DNA?
a) Adenine
b) Cytosine
c) Guanine
d) Thymine

6) Amoebic dysentery can be confirmed by
a) Examining the blood
b) Examining the faeces
c) Examining the urine
d) All of the above

7) Sexually reproducing organisms contribute
to their offspring

a) All of their genes
b) One half of their genes
c) One fourth of their genes
d) Double the number of their genes

8) In a genetic cross having recessive
the phenotypic ratio would be

a) 9:6:1
b) 15:1
c) 9:3:4
d) 12:3:1

9) In a dihybrid cross,
a ratio of 15:1 is due to

a) Supplementary genes
b) Dominant epistasis
c) Duplicate genes
d) Recessive epistasis

10) Polymorphism is mainly due to
a) Monogenic inheritance
b) Polygenic inheritance
c) Both of the above
d) None of the above

11) A child of O-group has a
B-group father. The genotype
of the father will be


12) The percentage of heterozygous individuals obtained by
selfing of Rr individuals is

a) 100
b) 75
c) 50
d) 25

13) In a cross 45 tall and
14 dwarf plants were obtained. The genotype of the parents is


14) A man of A blood group
marries a woman of AB
blood group. Which blood type would their progeny never have?

a) AB
b) A
c) O
d) B

15) The process of removing
stamens from floral buds
during hybridisation experiments
is called

a) Capping
b) Selfing
c) Emasculation
d) Crossing

16) A woman with an albinic father marries an albino
man. The proportion of normal: albinic in
her progeny are

a) 2 normal : 1 albinic
b) All normal
c) All albinic
d) 1 normal : 1 albinic

17) Yellow colour is dominant
over green colour. In
a generation of 50% yellow
and 50% green individuals,
the parents are

a) Both homozygous
b) Both heterozygous
c) One of them heterozygous
d) None of the above

18) An AO group mother with an O group child sues an AB
group man for the fathership of the child. Which of the following statements is true?

a) The claim is correct
b) The man is the child’s father but the woman is not the mother
c) Both are not the child’s parents
d) The woman is the mother but the man is not the true father

19) The genes controlling seven traits in the pea studied
by Mendel were actually
located on

a) Seven chromosomes
b) Six chromosomes
c) Four chromosomes
d) Five chromosomes

20) The process of mating
between closely related
individuals is called

a) Self breeding
b) Inbreeding
c) Hybridisation
d) Heterosis

21) A brown eyed couple
has a blue-eyed child.
The trait of brown
eye (B) is dominant
over blue eye (b).
What is the genotype
of the couple?


22) A blue fowl obtained
from mating between
black and white fowls is selfed. The F2 ratio will be

a) 1 black : 2 white : 1 blue
b) 2 black : 1 white : 1 blue
c) 1 black : 2 blue : 1 white
d) None of the above

23) Which of the following is true?
a) Etiolation
is genetic while albinism is

b) Etiolation is not reversible
c) Etiolation is physiological but albinism is genetic
d) Etiolation and albinism are synonyms

24) Heterosis is
a) Hybrid weakness
b) Hybrid weakness and vigour
c) Hybrid vigour
d) Neither weakness nor vigour of

25) A genetic disorder
in Africans which
reduces oxygen
uptake is

a) Haemophilia
b) Pernicious anaemia
c) Anaemia
d) Sickle cell anaemia

26) Crossing over
in diploid organisms
is responsible

a) Dominance of genes
b) Linkage between genes
c) Recombination of linked genes
d) Segregation of alleles

27) Sickle cell
anaemia is an
example of

a) Epistasis
b) Codominance
c) Pleiotropy
d) Incomplete dominance

28) “Gametes
are never hybrid”.
It is a statement of the law of

a) Dominance
b) Segregation
c) Independent assortment
d) Random fertilisation

29) The theory that species increase by geometrical progression was
proposed by

a) Cuvier
b) Malthus
c) Lamarck
d) Darwin

30) The natural selection theory of Darwin is objected to,
because it

a) Stresses upon interspecific competition
b) Explains that natural calamities take a heavy annular toll of lives
c) Explains adaptation of certain inherited characters
d) Stresses upon slow and small variations

31) The replica plating experiment was conducted by
a) Esther Lederberg
b) R.A. Fischer
c) Joshua Lederberg
d) Both a and c

32) The initiating force of evolution is
a) Mutation
b) Natural selection
c) Adaptation
d) None of these

33) Which is a correct match?
a) Hugo de Vries-Oenothera lamarckiana
b) Morgan-father of genetics
c) Mendel-mutation
d) Darlington-DNA replication

34) The genetic basis of adaptation has been experimentally
demonstrated by

a) Esther Lederberg
b) Joshua Lederberg
c) Both the above
d) None of the above

35) The appearance of DDT-resistant mosquitoes is an instance

a) Divergent evolution
b) Current evolution
c) Convergent evolution
d) Parallel evolution

36) The present giraffe has a long neck as compared
to its ancestors. It could be due to

a) Inheritance of acquired characters
b) Speciation
c) isolation
d) Natural selection

37) The reason why some mutations which are harmful
do not get eliminated from the gene pool is that

a) They are dominant and show up more frequently
b) They have future survival value
c) They are recessive and carried by heterozygous individuals
d) Genetic drift occurs because of a small populations

38) Malignant or cancerous growth is a kind of mutation
which is localised and not transmitted to the offspring.
This can be called a

a) Reverse mutation
b) Somatic mutation
c) Point mutation
d) Rearrangement mutation

39) The functional unit of mutation is the
a) Gene
b) Muton
c) Recon
d) Cistron

40) Genetic information is passed from one cell to another by
a) Sexuality
b) Mitosis
c) Meiosis
d) Crossing over

41) The number of codons in the genetic triplet code is
a) 4
b) 16
c) 32
d) 64

42) The initiation codons for protein synthesis are
a) UUU and GGG
b) AAU and UAA
c) AUG and GUA
d) GUG and AUG

43) The termination codons for protein synthesis are
a) AUU, AUG and GUU
b) UGA, UAA and UAG
c) UAU, UAG and UUA
d) AAA, UUU and UGA

44) The area of unwinding and separation of DNA strands during replication is called the
a) Origin
b) Initiation point
c) Primer
d) Replication fork

45) In DNA replication, the primer is a
a) Small deoxyribonucleotide polymer
b) Small ribonucleotide polymer
c) Helix destabilising protein
d) Enzyme taking part in joining nucleotides to their complementary template bases.

46) DNA strand is synthesised in the direction

47) Okazaki fragments are joined by
a) DNA polymerase III
b) DNA ligase
c) DNA polymerase II
d) DNA polymerase I

48) Okazaki fragments give rise to the
a) Master strand
b) Sense strand
c) Lagging strand
d) Leading strand

49) In proof reading during DNA replication
a) Wrong nucleotides are inserted
b) Wrong nucleotides are taken out
c) Wrong nucleotides are removed and correct ones are inserted
d) Mutations are prevented

50) Nonsense codons take part in
a) Helping protein synthesis
b) Termination of the gene message for polypeptide synthesis
c) Initiating the gene message for polypeptide synthesis
d) Synthesis of nonprotein amino acids

51) The two strands of DNA are
a) Similar and parallel
b) Similar but antiparallel
c) Complementary and antiparallel
d) Complementary and parallel

52) DNA acts as a template for synthesis of
a) DNA
b) RNA
c) Both DNA and RNA
d) Protein

53) In polypeptide synthesis, amino acids are brought over to the ribosome-mRNA complex by
a) rRNA
b) tRNA
c) DNA
d) Nucleotides

54) tRNA attaches amino acid at its
c) Anticodon
d) Loop

55) The blender experiment to prove that DNA is the genetic material was performed by
a) Hershey and Chase
b) Messelson and Stahl
c) Watson and Crick
d) Rosalind Franklin

56) The strain of Neurospora which grows on minimal medium is called
a) Autotroph
b) Prototroph
c) Auxotroph
d) Heterotroph

57) The scientists who received the Nobel Prize in 1958 for their contribution to biochemical genetics were
a) Beadle and Tatum
b) Beadle and Lederberg
c) Lederberg and Zinder
d) Zinder and Morgan

58) The one gene-one enzyme hypothesis was proposed by
a) Khorana and Nirenberg
b) Beadle and Tatum
c) Bateson and Punnet
d) Bridges

59) A mutant strain of Neurospora which fails to grow on a minimal medium unless supplemented with a nutrient is called an
a) Auxotroph
b) Autotroph
c) Heterotroph
d) Prototroph

60) The terms triplet code and genetic code were coined by
a) Watson and Crick
b) Nirenberg
c) Gamow
d) Conrad

61) The first codon discovered by Nirenberg and Mathaei was
a) GGG
b) CCC
c) UUU
d) AAA

62) Escherichia coli is fully labelled with
medium. The two strands of the DNA molecule of the first generation bacteria have

a) Different densities and do not resemble the parent DNA
b) Different densities but resemble the parent DNA
c) The same density and resemble the parent DNA
d) The same density but do not resemble the parent DNA

63) Semiconservative DNA/chromosome replication using
was demonstrated by

a) Messelson
b) Taylor
c) Messelson and Stahl
d) Hershey and Chase

64) DNA replication requires
a) DNA polymerase
b) RNA polymerase and translocase
c) DNA ligase
d) DNA polymerase and DNA ligase

65) In DNA if 10% of guanine is present, how much thymine is present?
a) 10%
b) 40%
c) 80%
d) 20%

66) Which ratio is constant for DNA?

67) Which one is not true?
a) A=T, G=C
b) A=G, T=C
c) C=G, T=A
d) G=C, A=T

68) The nucleotide arrangement in DNA can be seen by:
a) Light microscopy
b) Electron microscopy
c) Ultracentrifugation
d) X-ray crystallography

69) Radio tracer techniques show that DNA is in the:
a) Multi-helix stage
b) Double-helix stage
c) Single-helix stage
d) None of these

70) Watson and Crick got the Nobel Prize for proposing the DNA model in
a) 1959
b) 1962
c) 1968
d) 1990

71) The double-helix model of DNA resembles a twisted ladder in which the rungs
of the ladder are

a) a purine paired with a pyrimidine
b) a paired G and C paired with T
c) sugar-phosphate paired with sugar phosphate
d) both (a) and (b) are correct

72) Watson and Crick’s model of DNA is duplexed with
d) none of these

73) The two strands of DNA are held together by
a) Peptide bonds
b) S-S bonds
c) Phosphodiester bonds
d) Hydrogen bonds

74) A double stranded DNA virus with 20,000 base pairs has the following number of nucleotides:
a) 10,000
b) 20,000
c) 40,000
d) 666

75) The number of hydrogen bonds between cytosine and guanine are
a) 3
b) 2
c) 1
d) 4

76) Double hydrogen bonds occur in DNA between
a) Thymine and Uracil
b) Adenine and Thymine
c) Thymine and Cytosine
d) Adenine and Guanine

77) Which of the following statements regarding a double-helical molecule
of DNA is true?

a) Each strand is identical
b) Each strand replicates itself
c) All hydroxyl groups of pentose are involved in linkages
d) The bases are perpendicular to the axis

78) All the following compose nucleosides except the
a) purine base
b) pentose sugar
c) phosphate group
d) ribose sugar

79) DNA strands are anti-parallel because of
a) Disulphide bonds
b) Hydrogen bonds
c) Phosphate diester bonds
d) None of these

80) Hydrogen bonding in DNA occurs between the
a) Bases
b) Ribose sugar
c) Deoxyribose sugar

81) The carbon atoms of the pentose sugar involved in phosphodiester bond
formation in DNA and RNA are


82) If an isolated strain of DNA is kept at ,

a) It changes into RNA
b) It uncoils into helices
c) It divides into one million pieces
d) There is no effect

83) DNA synthesis takes place during
a) Metaphase
b) Anaphase
c) Interphase
d) Prophase

84) Duplication of DNA is called
a) Transduction
b) Transcription
c) Replication
d) Translation

85) Which of the following is capable of self replication?
a) DNA
b) RNA
c) Protein
d) Enzyme

86) The usual method of DNA replication is
a) Conservative
b) Dispersive
c) Semiconservation
d) Nonconservative

87) The operon model of gene regulation and organisation of prokaryotes was
proposed by

a) Messelson and Stahl
b) Wilkins and Franklin
c) Beadle and Tatum
d) Jacob and Monod

88) The smallest unit affected by mutation is the
a) Muton
b) Cistron
c) Recon
d) Exon

89) Genes regulate growth and differentiation through
a) Transcription and translation
b) Transduction and translation
c) Transformation
d) Translation

90) Viroids differ from viruses in being
a) Satellite RNA packaged with viral genome
b) Naked DNA molecules
c) Naked RNA molecules only
d) Naked DNA packaged with viral genome

91) In Escherichia coli, the lac operon is induced by
a) Lactose
b) The promoter gene
c) The regulator gene
d) The inducer gene

92) Tobacco Mosaic Virus (TMV) genes are
a) Double stranded RNA
b) Single stranded RNA
c) Polyribonucleotides
d) Proteinaceous

93) Which cannot be grown on an artificial medium?
a) Escherichia coli
b) TMV
c) Aspergillus
d) Yeast

94) Tobacco Mosaic Virus was crystallised for the first time by
a) Edward Jenner
b) Louis Pasteur
c) Andre Lwoff
d) W.N. Stanley

95) The virus attacking blue-green algae is known as a
a) Cyanophage
b) Coliphage
c) Bacteriophage
d) Zoophage

96) The polytene chromosomes were discovered for the first time in
a) Chironomus
b) Fruit fly
c) Drosophila
d) Housefly

97) Chromosomes are seen longest in the
a) Prophase of Meiosis-1
b) Prophase of Mitosis
c) Metaphase
d) Telophase

98) Which type of chromosomes segregate when a cell undergoes meiosis?
a) Homologous chromosomes
b) Non homologous
c) Both types of chromosomes
d) Centric and eccentric chromosomes

99) During the study of meiosis in Neurospora 2a, 4A, 2a arrangement of ascospores was observed. This meant that the
a) First division and second division were both equational
b) First division was reductional and second equational
c) First division was equational and second reductional
d) First and second divisions were both reductional

100) The product of meiosis are four nuclei which are not genetically identical because of
a) Crossing over
b) Random assortment of maternal and paternal chromosomes
c) Both (a) and (b)
d) Nuclear division


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