Molecular Basis of Inheritance MCQs with Answers

Question-1. Segments of mRNA removed during splicing are called

1. exons
2. promotor regions
3. integrator regions
4. introns

Question-2. Sex is determined in human beings

1. at the time of fertilization
2. 40 days after fertilization
3. seventh to eight week when genitals differentiate in foetus
4. by ovum

Question-3. The amino acid attaches to the tRNA at its:

1. 5' - end
2. Anti codon site
3. DHU loop
4. 3' - end

Question-4. The change of the light coloured variety of peppered moth (Biston betulari

1. is due to a) mutation
2. regeneration
3. genetic isolationd) temporal isolation
4. to its darker variety (Biston carbonari

Question-5. The fact that a purine base always paired through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix

1. uniform length in all DNA
2. the semiconservative nature
3. the antiparallel nature
4. uniform width throughout DNA

Question-6. The first genetic material could be

1. DNA
2. carbohydrates
3. protein
4. RNA

Question-7. The human chromosome with the highest and least number of genes in them are respectively

1. Chromosome 1 and X
2. Chromosome X and Y
3. Chromosome 21 and Y
4. Chromosome 1 and Y

Question-8. The most striking example of point mutation is found in a disease called

1. night blindness
2. DownÂ’s syndrome
3. sickle cell anaemia
4. thalassemia

Question-9. The net electric charge on DNA and histones is

1. both negative
2. both positive
3. zero
4. negative and positive, respectively

Question-10. The number of base substitution possible in amino acid codons is

1. 264
2. 535
3. 549
4. 261

Question-11. The polytene chromosomes were discovered for the first time in

1. Chironomus
2. Musca nebulo
3. Musca domestica
4. Drosophila

Question-12. The process of transfer of genetic information from DNA to RNA/formation of RNA from DNA is

1. transcription
2. translation
3. translocation
4. trnsversion

Question-13. The process of translation is

1. protein synthesis
2. DNA synthesis
3. RNA synthesis
4. ribosome synthesis

Question-14. The promoter site and the terminator site for transcription are located at

1. the 5' (upstream) end
2. the 3' (downstream) end
3. 3' (downstream) end and 5' (upstream) end, respectively of the transcription unit
4. 5' (upstream) end and 3' (downstream) end, respectively of thetranscription unit

Question-15. The RNA polymerase holoenzyme transcribes:

1. the structural gene only
2. the promoter, and the
3. the promoter, structural gene and the terminator region
4. the structural gene and the terminator regions

Question-16. The scientists involved in discovery of DNA as chemical basis of heredity were

1. Griffith and Avery
2. Avery, Mac Leod and McCarty
3. Watson and Crick
4. Hershey and Chase

Question-17. The transforming principle of Pneumococcus as found out by Avery, MacLeod and McCarty was

1. DNA
2. protein
3. polysaccharide
4. mRNA

Question-18. The translation termination triplet is

1. UAA
2. UAC
3. UGC
4. UAU

Question-19. The two strands of DNA are held together by

1. phosphodiester bonds
2. hydrogen bonds
3. S – S bonds
4. peptide bonds

Question-20. The wild type E. coli cells are growing in normal medium with glucose. They are transferred to a medium containing only lactose as sugar. Which of the following changes takes place?

1. All operons are induced
2. The lac operon is induced
3. E. coli cells stop dividing
4. The lac operon is repressed

Question-21. To initiate translation, the mRNA first binds to

1. The larger ribosomal sub-unit
2. The whole ribosome
3. No such specificity exists
4. The smaller ribosomal sub-unit

Question-22. What is the nature of the strands of the DNA duplex?

1. Identical and complementary
2. Anti=parallel and non-complementary
3. Dissimilar and non-complementary
4. Anti-parallel and complementary

Question-23. Which is not involved in protein synthesis?

1. Initiation
2. Elongation
3. Termination
4. Transcription

Question-24. Which of the following are the functions of RNA?

1. It is a constituent component of ribosomes
2. It carries amino acids to ribosomes
3. It is a carrier of genetic information from DNA to ribosomes synthesising polypeptides
4. All of the above

Question-25. Which of the following is correct for Watson and CrickÂ’s model of DNA. It is duplex with

1. 10 base pairs and 3.4 Ã… distance for each turn of spiral.
2. 20 base pairs and 34 Ã… for each turn.
3. None of the above
4. 10 base pairs and 3.4 Ã… distance for every turn.

Question-26. Which of the following statements is the most appropriate for sickle cell anaemia?

1. It confers resistance to acquiring malaria
2. It is a molecular disease
3. It cannot be treated with iron supplements
4. All of the above

Question-27. Which of the following steps in transcription is catalysed by RNA polymerse?

1. Initiation
2. Termination
3. All of the above
4. Elongation

Question-28. Which one is a hereditary disease?

1. Leprosy
2. Blindness
3. Phenylketonuria
4. Cataract

Question-29. Which was the last human chromosome to be completely sequenced:

1. Chromosome 11
2. Chromosome 21
3. Chromosome x
4. Chromosome 1

Question-30. While analysing the DNA of an organism a total number of 5386 nucleotides were found out of which the proportion of different bases were: Adenine : 29%, Guanine : 17%, Cytosine : 32%, Thymine : 17%. Considering the ChargaffÂ’s rule it can be concluded that:

1. it is a double stranded circular DNA
2. It is a double stranded linear DNA
3. No conclusion can be drawn
4. It is single stranded DNA

Question-31. Who amongst the following scientists had no contribution in the development of the double helix model for the structure of DNA?

1. Erwin Chargaff
2. Maurice Wilkins
3. Rosalind Franklin
4. Meselson and Stahl

Question-32. Who proved that DNA is basic genetic material?

1. Watson
2. Boveri and Sutton
3. Hershey and Chase
4. Griffith

Question-33. With regard to mature mRNA in eukaryotes

1. exons and introns do not appear in the mature RNA
2. introns appear but exons do not appear in the mature RNA
3. both exons and introns appear in the mature RNA
4. exons appear but introns do not appear in the mature RNA

Question-34. A ribotide is made up of:

1. Deoxribose + Uracil + Phosphate
2. Thymine + Ribose + Phosphate
3. Deoxyribpse + Phosphate + Adenine
4. Ribose + Phosphate + Uracil

Question-35. Amino acid sequence, in protein synthesis is decided by the sequence of?

1. r-RNA
2. f-RNA
3. m-RNA
4. c-DNA

Question-36. Anticodon found in:

1. On t-RNA
2. On r-RNA
3. On m-RNA
4. On DNA

Question-37. Antiparallel strands of a DNA molecule means that:

1. One strand turns anticlockwise
2. The phosphate groups at the start of two DNA strands are in opposite position
3. The phosphate groups at the start of two DNA strands, at their ends, share the same position
4. One strand turns clockwise

Question-38. Coiling of DNA duplex is:

1. Right-handed
2. Parallel
3. All of these
4. Left-handed

Question-39. DNA double helix model was given by:

1. Khorana
2. Watson and Crick
3. Priestley
4. Knoll and Ruska

Question-40. DNA fragments are joined in a correct sequence by :

1. RNA polymerase
2. Helicase
3. DNA polymerase
4. DNA ligase

Question-41. DNA multiplication is also called:

1. Transduction
2. Translation
3. Transcription
4. Replication

Question-42. DNA repairing is done by:

1. By DNA Polymerase II
2. Both (a) and (b)
3. By Ligase
4. By DNA polymerase I

Question-43. DNA transcription, if nucleotide sequence of DNA strand, that is being coded in ATACG, then the nucleotide sequence in m-RNA would be:

1. TATGC
2. TCTGG
3. UAUGC
4. UATGC

Question-44. During DNA synthesis formed segment is:

1. RNA fragment
2. Okazaki fragment
3. RNA Primer
4. Polymerase fragment

Question-45. During Protein synthesis, atone point the process comes to a halt. Select the group of the three codons from the following, from which any one of the three could bring about this halt:

1. UAG, UGA, UAA
2. UUE, UCA, UCG
3. UUU, UCC, UAU
4. UUC, UUA, UAC

Question-46. During splicing axon attached and inducer enzyme for reaction:

1. RNA Catalase
2. RNA permease
3. RNA poloymerase
4. RNA Ligase

Question-47. Following is important in Ïranscription:

1. CAAT Box
2. Promotar
3. DNA Polymerase
4. DNA Methylase

Question-48. In a give DNA segment ATC ACC AGG ACC CCA ACA, the first base gets mutated. The effect of this on coding by the DNA segment will result in :

1. No change in the sequence
2. Complete change in the type and sequence of amino acid
3. Change in first amino acid only
4. One amino acid less in protein

Question-49. In a m-RNA, how many nucleotide sequence code for amino acid:

1. Two
2. Three
3. Four
4. One

Question-50. In DNA helix:

1. Polarity
2. Antiparallel Polarity
3. Disuiphide bond
4. Quadrate structure

Question-51. Inprokaryotic translation, GTP molecule required in at:

1. Joining of 30S sub-unit of ribosome with n-RNA
2. Joining of 30S m-RNA on Formyl-met-f-RNA
3. Joining of 50S subunit of ribosome with initiation complex
4. Formation of formyl-met-f-RNA

Question-52. Nitrogenous bases present in DNA:

1. Adenine, guanine, cytosine, uracil
2. Adenine, thymine, uracil
3. Guanine, uracil
4. Adenine, guanine, cytosine, thymine

Question-53. Okazaki fregments is:

1. small segments of DNA on leading stand
2. Small segments of DNA on lagging stand
3. None of these
4. RNA primer

Question-54. One of these is not prepared directly from DNA

1. f-RNA
2. r-RNA
3. Protein
4. m-RNA

Question-55. RNA from which has clover leaf model:

1. r-RNA
2. hn-RNA
3. m-RNA
4. f-RNA

Question-56. the enzyme involved in transcription is:

1. DNA Polymerase II
2. RNA Polymerase
3. DNA Polymerase
4. DNA Polymerase I

Question-57. The ratio constant for a species is :

1. A+C/T + G
2. G + G/A + T
3. A + C/C + T
4. T+C/G + A

Question-58. Transposons occur in:

1. In Prokaryotes
2. In both (a) and (b)
3. None of these
4. In Eukaryotes

Question-59. Which is not component of lac operon:

1. Promoter gene
2. constructive gene
3. Regulator gene
4. Primer gene

Question-60. Which one is mainly transcribed:

1. Middle repetitive DNA sequence
2. Highly repetitive DNA sequence
3. Single copy of DNA sequence
4. Only RNA sequence

Question-61. Control of gene expression takes place at the level of

1. Translation
2. None of the above
3. DNA-replication
4. Transcription

Question-62. A bacterium grown over medium having radioactive 35S incorporates radioactivity in

1. proteins
2. DNA
3. RNA
4. carbohydrates

Question-63. A colourblind girl is rare because she will be born only when

1. her father and maternal grandfather were colourblind
2. her mother is colourblind and father has normal vision
3. parents have normal vision but grand parents were colourblind
4. her mother and maternal grandfather were colourblind

Question-64. A colourblind mother and normal father would have

1. colourblind sons and daughters
2. all colourblind
3. all normal
4. colourblind sons and normal/carrier daughters

Question-65. A colourblind woman marries a normal visioned male. In the offspring

1. all daughters are colourblind
2. all sons are normal
3. all sons are colourblind
4. both son and daughter are colourblind

Question-66. A DNA with unequal nitrogen bases would most probably be

1. double stranded
2. triple stranded
3. four stranded
4. single stranded

Question-67. A nucleoside differs from a nucleotide. It lacks the:

1. hydroxyl group
2. sugar
3. base
4. phosphate group

Question-68. A person with 47 chromosomes due to an additional Y-chromosome suffers from a condition called

1. Super female
2. TurnerÂ’s syndrome
3. KlinefelterÂ’s syndrome
4. Downs syndrome

Question-69. After crossing two plants, the progenies are found to be male sterile. This phenomenon is found to be maternally inherited and is due to some genes which are present in

1. chloroplast
2. mitochondria
3. cytoplasm
4. nucleus

Question-70. An enzyme that joins the ends of two strands of nucleic acid is a

1. synthetase
2. helicase
3. ligase
4. polymerase

Question-71. An individual exhibiting both male and female sexual characteristics in the body is known as

1. intersex
2. gynandromorph
3. bisexual
4. hermaphrodite

Question-72. Anticodon is an unpaired triplet of bases in an exposed position of

1. rRNA
2. tRNA
3. sRNA
4. mRNA

Question-73. Barr body in mammals represents

1. Y-chromosomes in somatic cells of male
2. all heterochromatin in male and female cells
3. one of the two X-chromosomes in somatic cells of females
4. all the heterochromatin in female cells

Question-74. Because most of the amino acids are represented by more than one codon, the genetic code is

1. Wobbling
2. degenerate
3. generate
4. overlapping

Question-75. Both deoxyribose and ribose belong to a class of sugars called

1. polysaccharides
2. hexoses
3. trioses
4. pentoses

Question-76. Both husband and wife have normal vision though their fathers were colourblind. The probability of their daughter becoming colourblind is

1. 25%
2. 50%
3. 75%
4. 0%

Question-77. Chargaffs rules are applicable to

1. single stranded DNA and RNA.
2. single stranded DNA.
3. double stranded DNA.
4. single stranded RNA.

Question-78. Diploid chromosome number in humans is

1. 44
2. 48
3. 42
4. 46

Question-79. DNA replication is

1. semi-conservative and semi-discontinuous.
2. semi-conservative and discontinuous.
3. conservative.
4. conservative and discontinuous.

Question-80. DNA template sequence of CTGATAGC is transcribed over mRNA as

1. GACUAUCG
2. GAUTATUG
3. UACTATCU
4. GUCTUTCG

Question-81. DownÂ’s syndrome is due to

1. linkage
2. sex-linked inheritance
3. non-disjunction of chromosomes
4. crossing over

Question-82. During DNA replication, the strands separate by

1. topoisomerase
2. unwindase/helicase
3. gyrase
4. DNA polymerase

Question-83. During infection of E. coli cells by bacteriophage T2,

1. both proteins and nucleic acids enter the cell.
2. only proteins from the infecting phage can also be detected in progeny phage.
3. only nucleic acids enter the cell.
4. proteins are the only phage components that actually enter the infected cell.

Question-84. Escherichia coli fully labelled with N15 is allowed to grow in N14 medium. The two strands of DNA molecule of the first generation bacteria have

1. different density but resemble parent DNA
2. same density and resemble parent DNA
3. same density but do not resemble parent DNA
4. different density and do not resemble parent DNA

Question-85. Experimental material in the study of DNA replication has been

1. Neurospora crassa
2. Pneumococcus
3. Drosophila melanogaster
4. Escherichia coli

Question-86. Frame shift mutation occurs when

1. base is added.
2. base is deleted.
3. anticodons are not present.
4. base is deleted or added.

Question-87. Genes located on Y-chromosome are

1. sex-linked genes
2. autosomal genes
3. holandric genes
4. mutant genes

Question-88. Genetic code is

1. triplet, universal, non-ambiguous and nondegenerate.
2. triplet, universal, non-ambiguous and degenerate.
3. triplet, universal, ambiguous and non-degenerate.
4. triplet, universal, ambiguous and degenerate.

Question-89. H. J. Muller was awarded Nobel Prize for his

1. discovery that ionizing radiations can induce gene mutations
2. work on gene mapping in Drosophila
3. efforts to prevent the use of nuclear weapons
4. discovery that chemicals can induce gene mutations

Question-90. Haemophilia is more common in males because it is a

1. dominant character carried by Y-chromosome
2. dominant trait carried by X-chromosome
3. recessive trait carried by X-chromosome
4. recessive character carried by Y-chromosome

Question-91. If a double stranded DNA has 20% of cytosine, what will be the percentage of adenine in it?

1. 40%
2. 30%
3. 60%
4. 20%

Question-92. If the base sequence of a codon in mRNA is 5'-AUG-3', the sequence of tRNA pairing with it must be

1. 5' - AUG - 3'
2. 5' - GUA - 3'
3. 5' - UAC - 3'
4. 5' - CAU - 3'

Question-93. If the sequence of bases in DNA is ATTCGATG, then the sequence of bases in its transcript will be

1. UAAGCUAC
2. GUAGCUUA
3. AUUCGAUG
4. CAUCGAAU

Question-94. In a DNA strand the nucleotides are linked together by

1. glycosidic bonds
2. peptide bonds
3. hydrogen bonds
4. phosphodiester bonds

Question-95. In E.coli, the lac operon gets switched on when

1. repressor binds to operator
2. RNA polymerase binds to the operator
3. lactose is present and it binds to RNA polymerase
4. lactose is present and it binds to the repressor

Question-96. In Escherichia coli lac Operon is induced by

1. promoter gene
2. ß-galactosidase
3. I-gene
4. lactose

Question-97. In eukaryotes, mRNA is synthesized with the aid of

1. RNA polmerase II.
2. RNA polymerase I.
3. reverse transcriptase.
4. RNA polymerase III.

Question-98. In human beings 45 chromosomes/single X/XO abnormality causes

1. KlinefelterÂ’s syndrome
2. TurnerÂ’s syndrome
3. EdwardÂ’s syndrome
4. Downs syndrome

Question-99. In some viruses, RNA is present instead of DNA indicating that

1. they cannot replicate.
2. there is no hereditary information.
3. RNA can act to transfer heredity.
4. their nucleic acid must combine with host DNA before replication.

Question-100. In split genes, the coding sequence are called

1. operons
2. exons
3. cistrons
4. introns

Question-101. In Streptococcus pneumoniae

1. virulent form is rough.
2. nonvirulent form is capsulated.
3. all forms are rough.
4. virulent form is smooth.

Question-102. Initiation codon of protein synthesis (in eukaryotes) is

1. GCA
2. CCA
3. AUG
4. GUA

Question-103. Khorana first deciphered the triplet codons of

1. threonine and histidine
2. tyrosine and tryptophan
3. phenylalanine and methionine
4. serine and isoleucine

Question-104. Lactose operon produces enzymes

1. b-galactosidase, permease and transacetylase.
2. permease, glycogen synthetase and transacetylase.
3. b-galactosidase, permease and phosphoglucose isomerase.
4. b-galactosidase, permease and glycogen synthetase.

Question-105. Leading strand during DNA replication is formed

1. in short segments.
2. first.
3. ahead of replication.
4. continuously.

Question-106. Methyl guanosine triphosphate is added at 5' end of hn-RNA in a process of

1. splicing
2. capping
3. None of these
4. tailing

Question-107. Mr. Kapoor has Bb autosomal gene pair and d allele sex-linked. What shall be proportion of Bd in sperms?

1. 1/4
2. 1/8
3. 1/2

Question-108. Nucleosome core is made of

1. H1, H2A, H2B, H4
2. H1, H2A, H2B, H3 and H4
3. H2A, H2B, H3 and H4
4. H1, H2A, H2B and H3

Question-109. Nucleotide arrangement in DNA can be seen by

1. electron microscope
2. ultracentrifuge
3. light microscope
4. X-ray crystallography

Question-110. Of a normal couple, half the sons are haemophilic while half the daughters are carriers. The gene is located on

1. Y-chromosome of father
2. one X-chromosome of mother
3. both the X-chromosomes of mother
4. X-chromosome of father

Question-111. Of both normal parents, the chance of a male child becoming colourblind are

1. possible only when all the four grand parents had normal vision
2. possible only when fatherÂ’s mother was colourblind
3. possible only when motherÂ’s father was colourblind
4. no

Question-112. Okazaki fragments are seen during

1. translation
2. replication
3. transduction
4. transcription

Question-113. One turn of DNA possesses

1. two base pairs
2. five base pairs
3. ten base pairs
4. one base pair

Question-114. Out of 8 ascospores formed in Neurospora the arrangement is 2a : 4a : 2a showing

1. some meiosis
2. second generation division
3. first generation division
4. no crossing over

Question-115. Out of A=T, G =C pairing, bases of DNA may exist in alternate valency state owing to arrangement called

1. tautomerizational mutation
2. frameshift mutation
3. point mutation
4. analogue substitution

Question-116. Protein helping in opening of DNA double helix in front of replications fork is

1. DNA polymerase-I
2. DNAligase
3. topoisomerase
4. DNAgyrase

Question-117. Regulatory proteins are the accessory proteins that interact with RNA polymerase and affect its role in transcription. Which of the following statements is correct about regulatory protein?

1. They interact with RNA polymerase but do not affect the expression
2. They only decrease expression
3. They only increase expression
4. They can act both as activators and as repressors

Question-118. Reverse transcriptase is

1. DNA dependent RNA polymerase
2. DNA dependent DNA polymerase
3. RNA dependent DNA polymerase
4. RNA dependent RNA polymerase