Genetics MCQs Part 9

1) Which type of DNA is found in bacteria ?
a) Membrane bound DNA
b) Circular free DNA
c) Straight DNA
d) Helical DNA

2) Transcription is the transfer of genetic information from
a) Chromosome to cytoplasm
b) tRNA to m RNA
c) DNA to m RNA
d) mRNA to rRNA

3) In split genes, the coding sequences are called
a) Cistrons
b) Operons
c) Exons
d) Introns

4) The lac operon is an example of a/an
a) Arabinose operon
b) Inducible operon
c) Repressible operon
d) Overlappin genes

5) The prokaryotic genetic system has
a) Either DNA or histones
b) Neither DNA nor histones
c) Both DNA and histones
d) DNA but no histones

6) Reverse transcriptase is
a) RNA- dependent RNA polymerase
b) RNA dependent DNA polymerase
c) DNA dependent RNA polymerase
d) DNA dependent DNA polymerase

7) A husband and wife have normal vision but the fathers of both of them were colour blind. The probability of their first daughter being colour blind is
a) 25 %
b) 50 %
c) 75 %
d) 0 %

8) Genetic drift
a) Is an orderly change in gene frequencies
b) Produces greatest fluctuations in large populations
c) Is the random change in gene frequencies
d) Has nothing in common with inbreeding

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

10) A child is born with an extra chromosome in each of its cells. This condition is usually the result of
a) Segregation
b) Hybridization
c) Non disjunction
d) Crossing over

11) The genes that keep on changing their location on the chromosome are
a) Pleiotropic genes
b) Jumping genes
c) Duplicate genes
d) Split genes

12) The major genes controlling the qualitative characteristics which show normal Mendelian inheritance are called
a) Pseudogenes
b) Oligogenes
c) Pangenes
d) Eugenics

13) Which of the following is used for experiments on DNA replication?
a) neurospora
b) TMV
c) E. coli
d) Drosophila

14) Transcription is the
a) Assembly of amino acids by m RNA in the form of polypeptides
b) Recognition of amino acids by RNA synthesis
c) Transfer of genetic information from DNA to RNA
d) Recognition of base sequence on m RNA

15) There are 64 codons in the genetic code dictionary because
a) There are 64 types of t-RNA found in the cell
b) There are 44 meaningless and 20 codons for amino acids
c) There are 64 amino acids to be coded
d) The genetic code is triplet

16) Dr. H.G. Khorana deciphered first the triplet codon of
a) Tyrosine and tryptophan
b) Threonine and histidine
c) Serine and isoleucine
d) Phenylalanine and methionine

17) The initation codon in higher plants is
a) UAG
b) AUG
c) AGU
d) GAU

18) Trisomy of autosome 21 causes
a) Meningitis
b) Mongolism
c) Beri-beri
d) Cretinism

19) The base found in RNA but not in DNA
a) Adenine
b) Uracil
c) Thymine
d) Guanine

20) Which strand has four pyrimidines?

21) RNA takes part in the synthesis of
a) D N A
b) Protein
c) Carbohydrates
d) Fat

22) Adenine is a
a) Purine
b) Pyrimidine
c) Nucleoside
d) Nucleotide

23) GCATG of one DNA strand will have base sequence on the second strand as follows:

24) The codons causing chain termination are

25) Genes are packaged into a bacterial chromosome by
a) Histones
b) Basic proteins
c) Acidic proteins
d) Actin

26) The contrasting pairs of factors in Mendelian crosses are called
a) Alloloci
b) Paramorphs
c) Multiple alleles
d) Allelomorphs

27) The term gene which was coined by Johannsen was termed by Mendel as
a) Replicon
b) Factor
c) Active principle
d) Cistron

28) In sickle cell anaemia, death is caused when the lethal genes are present in a
a) Heterozygous condition
b) Homozygous dominant condition
c) Homozygous recessive condition
d) Co-dominant condition

29) The genophore is the name of
a) DNA of eukaryotes
b) DNA of bacteria
c) Genes of Drosophila
d) Genes of Neurospora

30) In bacteria
a) DNA is doubled stranded and ring-shaped
b) DNA is scattered
c) DNA is enclosed in the nucleus
d) DNA is 4 stranded in the nucleus

31) The genotype is a term used to designate the genetic make up of
a) A chromosome
b) A gamete
c) An organ
d) An individual

32) The process of mating of individuals which are more closely related than the average of the population to which they belong is called
a) Inbreeding
b) Hybridization
c) Heterosis
d) Self breeding

33) Mendel’s laws apply only when
a) F1 in monohybrid cross shows two types of

b) The characters are linked
c) the parents are pure breeding
d) the first pair of contrasting character is dependent upon the other pairs

34) A fruit fly heterozygous for sex-linked genes, is mated with a normal female fruit fly. The male-specified chromosome is likely to enter egg cells in the proportion of
a) 1 : 1
b) 1 : 2
c) 3 : 1
d) 7 : 1

35) Which law would have been violated if Mendel had chosen eight characters in the garden pea?
a) Law of dominance
b) Law of segregation
c) Principle of independent assortment
d) Law of purity of gametes

36) At what stage is the crossing-over most easily observable or becomes optically apparent as chiasmata?
a) Meiosis-II or Mitotic prophase
b) Diakinesis
c) Diplotene
d) Metaphase

37) The four nuclei produced by reduction division differ among themselves in the
a) Number of chromosomes
b) Size of chromosomes
c) Number of genes
d) Quality of genes

38) The exchange of genetic material between chromatids of paired homologous chromosomes during the first meiotic division is called
a) Synapsis
b) Chiasmata
c) Transformation
d) Crossing over

39) A person with the sex chromosomes XXY must be suffering from
a) Down’s syndrome
b) Klinefelter’s syndrome
c) Turner’s syndrome
d) Gynandromorphism

40) In humans, a sex linked trait is
a) Down’s syndrome
b) Colour blindness
c) Curly hair
d) Sickle cell anaemia

41) A new crop ‘Triticale’ has been evolved by intergeneric hybridization between
a) Rice and maize
b) Wheat and rye
c) Wheat and Aegilops
d) Wheat and rice

42) The mongoloid condition is related to
a) Monosomy of the 23rd
b) Trisomy of the 21st
c) Nullisomy of the 10th
d) the Mongolian climate

43) The minimum requirement for mutation is a
a) Change in a single nucleotide
b) Change in a single strand of DNA
c) Change in a triplet codon
d) Change in the whole DNA

44) One of the reasons why haploids are considered more suitable than diploids for the study of mutations is that
a) Haploids have a shorter generation time
b) Haploids have a smaller number of chromosomes
c) Haploids allow expression of recessive mutations immediately
d) Haploids can be obtained in large numbers to give a correct estimate of mutation theory

45) When a certain character is inherited only through the female parent, it probably represents the case of
a) Mendelian nuclear inheritance
b) Multiple plastid inheritance
c) Cytoplasmic inheritance
d) Incomplete dominance

46) When a female albino plant of maize is crossed with a normal green male plant, all the plants in the progeny are albino because
a) Plastids are inherited through the maternal parents
b) Albinism is dominant over green character
c) The crossing results in structural changes in green plastids
d) Green plastids of the male parents become mutated

47) Different mutations referrable to the same locus of chromosome give rise to
a) Pseudoalleles
b) Polygenes
c) Oncogenes
d) Multiple alleles

48) The nucleosome core is made of
a) H1, H2A, H2B and H3
b) H1, H2A, H2B, H4
c) H1, H2A, H2B, H3 and H4
d) H2A, H2B, H3 and H4

49) Linkage in plants was first shown in
a) Zea mays
b) Lathyrus odoratus
c) Oenothera lamarckiana
d) Pisum sativum

50) In a dihybrid cross, two recessive genes showed 10% recombinants. The distance between two genes is
a) 10 map units
b) 20 map units
c) 30 map units
d) 40 map units

51) Harmful mutations do not get eliminated from the gene pool because
a) They have survival value
b) Of genetic drift
c) They are formed repeatedly
d) They are recessive and carried by heterozygous individuals

52) Cytoplasmic male sterility is passed down
a) Through bacteriophage
b) Paternally
c) Maternally
d) Biparentally

53) Which histone is not a component of the nu particle?
a) H2
b) H1
c) H3
d) H4

54) The Nobel Prize for jumping genes/transposable DNA elements was given to
a) Muller
b) Mc Clintock
c) Morgan
d) Kornberg

55) Hexaploid or modern wheat was developed through
a) Hybridomas
b) Chromosome doubling
c) Hybridisation
d) Hybridisation and chromosome doubling

56) Formation of multivalents in meiosis is due to
a) Deletion
b) Inversion
c) Monosomy
d) Reciprocal translocation

57) Genes located on mitochondrial DNA bring about
a) Paternal inheritance
b) Maternal inheritance
c) Biparental inheritance
d) There is no inheritance

58) The symbol of empty circles used in pedigree analysis represents
a) Normal females
b) Normal males
c) Affected females
d) Affected males

59) AB genes are linked. What is the genotype of the progeny in a cross between AB/ab and ab/ab
a) AABB and aabb
b) AaBb and aabb
c) AAbb and aaBB
d) AaBb and AaBb

60) The lack of independent assortment between two genes A and B would be due to
a) Crossing over
b) Linkage
c) Repulsion
d) Recombination

61) A heterochromatic region is
a) Genetically more active
b) Genetically less active
c) A loosely coiled region
d) A light-coloured region

62) Cri-du-chat syndrome in humans is caused by
a) Trisomy of the 21st chromosome
b) Loss of half of the short arm of chromosome 5
c) Loss of half of the long arm of chromosome 5
d) Fertilization of an XX egg by a normal Y-bearing sperm

63) The gene for cystic fibrosis is located over chromosome
a) 4
b) 7
c) 11
d) 12

64) The longest chromosomes occur in
a) Lilium
b) Zea mays
c) Allium
d) Trillium

65) Telomeres with repetitive DNA sequences
a) Act as replicons
b) Are transcription initiators
c) Help in chromosome pairing
d) Prevent chromosome loss

66) The three principles of Mendelism are
a) Dominance-recessiveness, segregation and independent assortment
b) Linkage, segregation and independent assortment
c) Linkage, dominance-recessiveness and segregation
d) Linkage, dominance-recessiveness and independent assortment

67) The F2 generation of a cross between two white flowered strains of Sweet Pea yields 9 purple flowered plants; 7 white flowered plants. This is an example of
a) Epistasis
b) Complementary genes
c) Supplementary genes
d) Gene inhibition

68) The ABO blood group system is due to
a) Multifactor inheritance
b) Incomplete dominance
c) Multiple allelism
d) Epistasis

69) The procedure adopted by Mendel which was different from his predecessors was
a) Keeping breeding records
b) Employing many traits at one time
c) Differentiating inherited traits
d) Quantitative analysis of data

70) An exception to Mendel’s principles is
a) Dominance
b) Purity of gametes/segregation
c) Linkage
d) Independent assortment

71) A back cross is
a) F1 x F1
b) F1 x Recessive parent
c) F1 x Dominant parent
d) F1 x Any parent

72) A dihybrid cross is related to the
a) Principle of dominance
b) Principle of independent assortment
c) Principle of segregation
d) Principle of purity of gametes

73) Which amino acid is substituted in sickle cell anaemia?
a) Glutamic acid by valine in a-chain
b) Glutamic acid by valine in ß-chain
c) Valine by glutamic acid in ß-chain
d) Valine by glutamic acid in a-chain

74) In a cross of red and white flowered Snapdragon, F1 plants will have flowers
a) Red
b) White
c) Both A and B
d) Pink

75) If Mendel had studied 7 traits using a plant with 12 chromosomes instead of 14, he would have
a) Discovered incomplete dominance
b) Not discovered the law of independent assortment
c) Discovered sex linkage
d) Mapped the chromosomes

76) Which is connected with multiple phenotypes?
a) Epistasis
b) Pleiotropy
c) Polygenic inheritance
d) Mutations

77) The dihybrid test cross ratio is
a) 9:3:3:1
b) 1:1:1:1
c) 3:1
d) 1:1

78) Epistasis is due to
a) Interaction of two alleles of the same gene
b) Interaction of two separate genes
c) Polygenes
d) Multiple alleles

79) 1:2:1 phenotypic and genotypic ratios occur in case of
a) Blending inheritance
b) Psuedoallels
c) Multiple alleles
d) Complementary genes

80) On crossing two similar hybrids, the percentage of recessives is
a) 50%
b) 75%
c) 25%
d) 100%

81) Three children in a family have blood types O, AB and B respectively. What are the genotypes of their parents
a) IAi and IBi
b) IAIB and ii
c) IBIB and IAI A
d) IAIA and IBi

82) Self fertilising trihybrid plants from
a) Eight different gametes and 64 different zygotes
b) Four different gametes and sixteen different zygotes
c) Eight different gametes and sixteen different zygotes
d) Eight different gametes and thirty two different zygotes

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

84) Polypeptide chain synthesis in eukaryotes is initiated by
a) Glycine
b) Leucine
c) Methionine
d) Lysine

85) The terms cistron, recon and muton were proposed by
a) Johannsen
b) Morgan
c) Lederberg
d) Benzer

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

87) The names, Temin and Baltimore, are associated with
a) Photorespiration
b) RNA synthesis
c) Reverse transcription
d) Translation

88) The lactose operon produces the enzymes
a) B-galactosidase, permease and glycogen synthetase
b) B-galactosidase, permease and transacetylase
c) Permease, glycogen synthetase and transacetylase
d) B-galactosidase, phosphoglucose, isomerase and permease

89) Which codon is related to UAG and UAA in function?
a) GUG
b) UGA
c) UUU
d) AUG

90) What happened when heat killed S-cells along with live R-cells were injected into mice?
a) The mice died and showed live S-cells
b) The mice survived and showed live S-cells
c) The mice died and showed live R-cells
d) The mice died and showed dead R-cells

91) Which is important for transcription?
a) CAAT Box
b) Promoter
c) DNA polymerase
d) DNA methylase

92) The breakthrough of the year 2002 is
a) mRNA
b) cDNA
c) miRNA
d) rDNA

93) cDNA is formed by
a) DNA dependent DNA polymerase
b) RNA dependent DNA polymerase
c) DNA dependent RNA polymerase
d) DNA ligase

94) Oncogenes were discovered by
a) Fleming
b) Rowland
c) Prusiner
d) Bishop and Vermus

95) -CCA 3 end of t-RNA is called
a) Anticodon loop
b) DHU loop
c) T y C
d) Amino acid binding site.

96) In DNA finger printing, analysis is made of
a) Satellite DNA
b) Moderately repetitive sequences
c) Microsatellites
d) Variable number of tandem repeats

97) A nucleosome is the portion of a chromosome containing
a) Only histones
b) Both DNA and histones
c) Only DNA
d) Both DNA and RNA

98) Find out the mismatch
a) Mc Clintock ……………… Jumping genes
b) Khorana …………………. Mutation induction in Drosophila
c) Landsteiner …………… Blood groups
d) Wallace ………………. Organic evolution

99) A sequential expression of a set of human genes occurs when a steroid molecule binds to
a) mRNA
b) DNA sequence
c) tRNA
d) Ribosome


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