Genetics MCQs Part VI

1) Fraternal twins in human beings are produced when
a) two sperms fertilize an ovum and the first two blastomeres separate from each other
b) one sperm fertilizes an ovum and first two blastomeres separate from each other
c) two ova are fertilized simultaneously
d) egg develops parthenogenetically and first two blastomeres separates from each other

2) Free-martin condition is observed in
a) monozygotic twins
b) dizygotic twins
c) both
d) none

3) Which of the following is a genetic trait in man?
a) Leucoderma
b) Albinism
c) Tuberculosis
d) Diphtheria

4) Albinism is a
a) deficiency disease
b) hereditary disease
c) contagious disease
d) sex-linked diseases

5) If an albino man marries albino woman, all their children would be
a) normal
b) albino
c) suffering from leucoderma
d) none

6) Albinism is
a) dominant
b) polygenic
c) recessive
d) none of the above

7) Albinism is a congenital disorder resulting from the lack of the enzyme:
a) tyrosinase
b) catalase
c) xanthine oxidase
d) melanase

8) In albinism, the absence of the following pigment makes the skin and hair very light coloured:
a) Chlorophyll
b) Haemoglobin
c) Melanin
d) Carotene

9) Sickle-cell anaemia is due to
a) hormones
b) viruses
c) bacteria
d) a genetic disorder

10) An example of a molecular mutation is
a) Anaemia
b) Erythroblastosis foetalis
c) Sickle-cell anemia
d) Haemophilia

11) The genotype of a person with `Sickle -cell trait` is
d) None

12) The person suffering from thalassemia is unable to produce
a) alpha chains
b) beta chains
c) delta chains
d) all of these

13) Who is known as the `Father of physiological genetics`?
a) Garrod
b) Galton
c) Mendel
d) Morgan

14) Which one is a hereditary disease?
a) Cataract
b) Leprosy
c) Phenylketonuria
d) Blindness

15) Ability of tasting PTC paper is a hereditary character. “T” is
dominant and “t” recessive. Which genotype will not be able to taste

a) TT
b) tt
c) Tt
d) None

16) Who has discovered the taste-blindness of phenyl thiocarbamide (PTC)?
a) Folling
b) Fox
c) Garrod
d) Levan

17) The process of improving the qualities of human race by careful selection of parents is known as
a) Gerontology
b) Euthenics
c) Eugenics
d) Genetic engineering

18) Eugenics is the study of
a) Evolution
b) Modern genetics
c) Development
d) Human genetic improvement

19) Eugenics pertains to
a) study of human genetics
b) improvement of mankind by improving human heredity
c) controlling the size of a human family
d) preserving human sperms for artificial insemination

20) The term `eugenics` was coined by
a) Lederberg
b) Urey
c) Francis Galton
d) Thomas Hunt Morgan

21) Marriage between close relatives should be avoided because it induces more
a) blood group abnormalities
b) mutations
c) recessive alleles to be inherited together
d) multiple births

22) Improvement of genetic characters and of the present day generation on the basis of the best nutrition and training is called
a) Gerontology
b) Euphenics
c) Eugenics
d) Euthenics

23) Study of improvement of human race by providing ideal “nurture” is called
a) Euthenics
b) Eugenics
c) Euphenics
d) None of these

24) Improvement of the human race by improving the environmental conditions is
a) Dysgenics
b) Euthenics
c) Eugenics
d) Euphenics

25) Intelligence quotient (IQ) is a ratio of mental age to
a) chronological age
b) chronological age multiplied by 10
c) chronological age divided by 100
d) chronological age multiplied by 100

26) Mental competence in relation to chronological age in man is called
a) Idiocy
b) Diligence
c) Intelligence
d) Intelligence quotient

27) The first to successfully fuse cells from different mammalian species (mouse and human) were:
a) Watson and Crick
b) Kornberg and Khorana
c) Jacob and Monod
d) Harris and Watkins

28) Restriction enzymes are used in genetic engineering because
a) they cut DNA at specific base sequences
b) they are proteolytic enzymes which can degrade harmful proteins
c) they are nucleases that cut DNA at variable sites
d) they can join together different DNA fragments

29) Restriction endonuclease is used for cutting
a) mRNA
b) RNA fragment
c) Double strand DNA
d) Single strand DNA

30) Which of the following is used in getting a specific part in genetic engineering?
a) Ligases
b) Restriction endonuclease
c) Lipid
d) Protein

31) Plasmids are
a) outgrowths of the cell membrane
b) ingrowths of the mitochondria
c) extrachromosomal circular material
d) outgrowths of the nuclear membrane

32) `Cloning` is meant for
a) production of HGH gene in E.coli
b) preserving the genotype of the organism
c) to replace the original one
d) all of these

33) Which of the following scientists produced a clone of adult lamb named “Dolly”?
a) J.B. Gurdon
b) Steen Willandsen
c) Ian Wilmut
d) Don Wolf

34) Which of the following cells was used for cloning “Dolly”?
a) Nerve cell
b) Liver cell
c) Udder cell
d) Muscle cell

35) The cloning of “Dolly” was carried out in
a) USA
b) UK
c) France
d) Japan

36) A woman with two genes for haemophilia and a gene for colour blindness on one of the X-chromosomes marries a normal man. How will the progeny be?
a) All sons and daughters haemophiliac and colour blind
b) Haemophilic and colour blind daughters
c) Among sons 50% will be haemophiliacs and 50% haemophiliacs as well as colour blind
d) 50% haemophiliac daughters and 50% colour blind daughters

37) In Down syndrome, karyotyping has shown that the disorder is associated
with trisomy of chromosome number 21 usually due to

a) nondisjunction during egg formation
b) nondisjunction during sperm cell formation
c) addition of an extra chromosome during the cleavage of the zygote
d) nondisjunction during egg cell production and sperm production

38) Mental retardation in a man associated with sex chromosomal abnormality is usually due to
a) increase in the number of X chromosome s
b) increase in the number of Y-chromosomes
c) increase in the size of the X-chromosome
d) increase in the size of the Y-chromosome

39) With respect to the ABO group there are four major blood types because this blood group is determined by
a) three alleles all of which are recessive
b) three alleles of which two are codominant
c) three alleles of which two are recessive and the third is dominant
d) three alleles all of which are dominant

40) Plants having similar genotypes produced by plant breeding are called
a) haploid
b) autoploid
c) genome
d) clones

41) Genes which confer antibiotic resistance on bacteria are located on
a) Polysomes
b) RNA
c) the circular DNA molecule
d) Plasmids

42) A colour blind daughter is born when
a) the mother is a carrier, the father is colour blind
b) the father is colour blind, the mother is normal
c) the mother is colour blind,the father is normal
d) the mother is a carrier, the father is normal

43) Identical twins are born when
a) one sperm fertilizes two ova
b) one ovum is fertilized by two sperms
c) two ova are fertilized
d) one fertilized ovum divides into two blastomeres and both of them develop separately

44) A genetic disease in many Africans which reduces the oxygen uptake by RBC is known as
a) Anaemia
b) Haemophilia
c) Sickle-cell anaemia
d) Pernicious anaemia

45) Sex chromosomes are found in the cells of the
a) Testes
b) Ovaries
c) Kidneys and liver
d) All the above

46) The genotype of an Rh positive person could be
a) RR
b) Rr
c) rr
d) both a and b

47) Intelligence is controlled by
a) many genes whose effect is cumulative
b) not controlled by genes at all
c) environment only
d) one gene only

48) Which theory was proposed by Bridges?
a) Hormonal control of sex
b) Development of gynandromorphs
c) Sex reversal
d) Genic balance

49) In which blood group are antigens absent?
a) A
b) B
c) O
d) AB

50) Red-green colour blindness in human is governed by a sex-linked recessive
gene. A normal woman whose father was colour-blind marries a colour-blind
man. What proportion of their daughters is expected to be colour blind?

b) All

51) One child is haemophiliac (a sex-linked trait), whereas its fraternal twin
brother is normal. Which one of the following information is most appropriate?

a) The other child is a female and the father is haemophilic
b) The haemophiliac child is a male
c) The mother must have been heterozygous
d) The child is a monozygotic twin

52) A clone is a group of individuals obtained through
a) hybridisation
b) self-pollination
c) cross-pollination
d) vegetative propagation

53) One turn of DNA possesses
a) One base pair
b) Two base pairs
c) Five base pairs
d) Ten base pairs

54) The polypeptide chain is initiated by
a) Glycine
b) Leucine
c) Methionine
d) Lysine

55) The process of protein synthesis in a cell is
a) Translocation
b) Translation
c) Transcription
d) Transduction

56) The molecule which is capable of self replication is
a) DNA
b) RNA
c) Enzyme
d) Protein

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

58) The degeneracy of the genetic code was discovered by
a) Khorana
b) Ochoa
c) McClintock
d) Bernfield and Nirenberg

59) The usual method of DNA replication is
a) Semiconservative
b) Conservative
c) Dispersive
d) Nonconservative

60) Escherichia coli with completely radioactive DNA was allowed to replicate
in a non-radioactive medium for two generations. The percentage of bacteria
with radioactive DNA is

a) 100%
b) 50%
c) 25%
d) 12.5%

61) DNA replication in eukaryotes commences
a) From both ends of a chromosome simultaneously
b) At several sites along the DNA of a chromosome simultaneously
c) From the centromere to either end
d) From one end of chromosome to the other.

62) In vitro synthesis of RNA and DNA was carried out first by
a) Kornberg and Nirenberg
b) Ochoa and Kornberg
c) Ochoa and Nirenberg
d) Nirenberg and Khorana

63) The genetic code determines
a) Sequence of amino acids in a protein chain
b) Variations
c) Constancy of morphological traits
d) Structural pattern

64) First deciphering of genetic code through trinucleotide synthesis was
performed by

a) Beadle and tatum
b) Watson and Crick
c) Nirenberg
d) Ochoa

65) Genetic code is said to be degenerate because
a) Codons degenerate very quickly
b) One amino acid is coded by more than one codon
c) One codon codes for more than one amino acid
d) None of the above

66) Nirenberg synthesised an RNA having 34 adenine residues (AAAA…) and
obtained a polypeptide of 11 lysine residues. It proved thatthe genetic code
for lysine is

a) Adenine
b) AA
c) AAA
d) AAAA…..A.

67) Khorana et al synthesised RNA with a copolymer of UGUGUGUGUG… it produced
a peptide with alternate cysteine and valine. The codons for the two are

a) UGU and GUG
b) UUG and GGU
c) GUG and UGU
d) UGG and GUU

68) Khorana first deciphered the triplet codons of
a) Serine and isoleucine
b) Cysteine and valine
c) Tyrosine and tryptophan
d) Phenylalanine and methionine

69) An anticodon of tRNA can recognise more than one codon of mRNA. This is the is
a) Wobble hypothesis
b) Gene flow hypothesis
c) Template hypothesis
d) Richmond and Lang effect

70) Wobble hypothesis establishes
a) Peptide chain formation
b) Initiation of peptide chain
c) Termination of peptide chain
d) Economy in tRNA molecules

71) The enzyme required for transcription is
a) RNA-ase
b) Endonuclease
c) RNA polymerase
d) DNA polymerase

72) Synthesis of DNA over an RNA template/teminism occurs in
a) TMV
b) Reovirus
c) Rous Sarcoma Virus

73) Experimental material in the study of DNA replication has been
a) Escherichia coli
b) Neurospora crassa
c) Pneumococcus
d) Drosophila melanogaster

74) The nucleotide arrangement in DNA can be seen by
a) X-ray crystallography
b) Electron microscope
c) Ultracentrifuge
d) Light microscope

75) A DNA with unequal nitrogen bases would most probably be
a) Single stranded
b) Double stranded
c) Triple stranded
d) Four stranded

76) The process of translation is
a) Ribosome synthesis
b) Protein synthesis
c) DNA synthesis
d) RNA synthesis

77) The transforming principle of Pneumococus as found out by Avery, MacLeod
and McCarty was

a) mRNA
b) DNA
c) Protein
d) Polysaccharide

78) Information transfer from RNA to DNA is
a) Transcription
b) Translation
c) Replication
d) Reverse transcription

79) A double stranded DNA virus with 20,000 base pairs has how many nucleotides?
a) 20,000
b) 10,000
c) 666
d) 40,000

80) A DNA nucleotide chain has AGCTTCGA squence. The nucleotide sequence
of the other chain would be


81) Circular DNA is present in
a) E.R. and ribosomes
b) Ribosomes and chloroplasts
c) Ribosomes and mitochondria
d) Mitochondria and chloroplasts

82) Arrangement of three successive bases in the genetic code signifies an
a) Protein
b) Amino acid
c) Nucleic acid
d) Plasmid

83) The DNA template sequence of CTGATAGC is transcribed over mRNA as

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

85) Nucleic acids are made of
a) Nucleotides
b) Nucleosides
c) Amino acids
d) Proteins

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

87) The codon for anticodon 3’UUA-5 is

88) The environmental agent triggering transcription from an operon is the
a) Inducer
b) Regulator
c) Derepressor
d) Controlling factor

89) Who proposed the central dogma of modern biology?
a) Watson and Crick
b) Beadle and Tatum
c) Klug
d) Crick

90) The nucleotide base present in DNA and not in RNA is
a) Cytosine
b) Uracil
c) Thymine
d) Guanine

91) Most RNA is present in the
a) Cytoplasm
b) Nucleoplasm
c) Nucleolus
d) Ribosome

92) DNA duplex shows
a) Right handed coiling and parallel
b) Right handed coiling and antiparallel
c) Left handed coiling and antiparallel
d) Left handed coiling and parallel

93) The amino acid binding site of tRNA is
a) 5′ end
b) Anticodon loop
c) DHU loop
d) CCA 3′ end

94) In a DNA molecule cytosine is 18%. Percentage of adenine would be
a) 32%
b) 64%
c) 36%
d) 18%

95) A sequence of 3 bases on tRNA which binds to an mRNA codon is termed
a) Triplet
b) Nonsense codon
c) Anticodon
d) Termination codon

96) X-ray diffraction shows DNA diameter to be

97) Which is true according to Chargaff’s rule?
a) A+G=T+C
b) A=C
c) G=T

98) Nucleic acids were discovered by
a) Watson and Crick
b) Khorana
c) Wilkins
d) Miescher

99) The type of coiling in B-DNA is
a) Right handed
b) Left handed
c) Zigzag
d) Opposite

100) Reverse transcription was discovered by
a) Beadle and Tatum
b) Temin and Baltimore
c) Watson and Crick
d) Khorana


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