Practice CBSE Class 12 Biology Molecular Basis of Inheritance MCQs Set A provided below. The MCQ Questions for Class 12 Chapter 5 Molecular Basis of Inheritance Biology with answers and follow the latest CBSE/ NCERT and KVS patterns. Refer to more Chapter-wise MCQs for CBSE Class 12 Biology and also download more latest study material for all subjects
MCQ for Class 12 Biology Chapter 5 Molecular Basis of Inheritance
Class 12 Biology students should review the 50 questions and answers to strengthen understanding of core concepts in Chapter 5 Molecular Basis of Inheritance
Chapter 5 Molecular Basis of Inheritance MCQ Questions Class 12 Biology with Answers
Question: The two strands of DNA are held together by
a) peptide bonds
b) phosphodiester bonds
c) hydrogen bonds
d) S – S bonds
Answer : C
Question: Nucleotide arrangement in DNA can be seen by
a) X-ray crystallography
b) electron microscope
c) ultracentrifuge
d) light microscope
Answer : A
Question: Chargaff’s rules are applicable to
a) single stranded RNA.
b) single stranded DNA and RNA.
c) single stranded DNA.
d) double stranded DNA.
Answer : D
Question: One turn of DNA possesses
a) one base pair
b) two base pairs
c) five base pairs
d) ten base pairs
Answer : D
Question: Which of the following is correct for Watson and Crick’s model of DNA. It is duplex with
a) 10 base pairs and 3.4 Å distance for every turn.
b) 10 base pairs and 3.4 Å distance for each turn of spiral.
c) 20 base pairs and 34 Å for each turn.
d) None of the above
Answer : A
Question: In Streptococcus pneumoniae
a) virulent form is smooth.
b) virulent form is rough.
c) nonvirulent form is capsulated.
d) all forms are rough.
Answer : A
Question: The scientists involved in discovery of DNA as chemical basis of heredity were
a) Hershey and Chase
b) Griffith and Avery
c) Avery, Mac Leod and McCarty
d) Watson and Crick
Answer : C
Question: During infection of E. coli cells by bacteriophage T2,
a) proteins are the only phage components that actually enter the infected cell.
b) both proteins and nucleic acids enter the cell.
c) only proteins from the infecting phage can also be detected in progeny phage.
d) only nucleic acids enter the cell.
Answer : D
Question: If a double stranded DNA has 20% of cytosine, what will be the percentage of adenine in it?
a) 20% b) 40%
c) 30% d) 60%
Answer : C
Question: In some viruses, RNA is present instead of DNA indicating that
a) their nucleic acid must combine with host DNA before replication.
b) they cannot replicate.
c) there is no hereditary information.
d) RNA can act to transfer heredity.
Answer : D
Question: In a DNA strand the nucleotides are linked together by
a) phosphodiester bonds
b) glycosidic bonds
c) peptide bonds
d) hydrogen bonds
Answer : phosphodiester bonds
Question: A nucleoside differs from a nucleotide. It lacks the:
a) phosphate group
b) hydroxyl group
c) sugar
d) base
Answer : phosphate group
Question: Both deoxyribose and ribose belong to a class of sugars called
a) pentoses
b) polysaccharides
c) hexoses
d) trioses
Answer : pentoses
Question: The fact that a purine base always paired through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix
a) uniform width throughout DNA
b) uniform length in all DNA
c) the semiconservative nature
d) the antiparallel nature
Answer : uniform width throughout DNA
Question: The net electric charge on DNA and histones is
a) negative and positive, respectively
b) both negative
c) both positive
d) zero
Answer : negative and positive, respectively
Question: The promoter site and the terminator site for transcription are located at
a) 5' (upstream) end and 3' (downstream) end, respectively of thetranscription unit
b) the 5' (upstream) end
c) the 3' (downstream) end
d) 3' (downstream) end and 5' (upstream) end, respectively of the transcription unit
Answer : 5' (upstream) end and 3' (downstream) end, respectively of thetranscription unit
Question: Which of the following statements is the most appropriate for sickle cell anaemia?
a) All of the above
b) It confers resistance to acquiring malaria
c) It is a molecular disease
d) It cannot be treated with iron supplements
Answer : All of the above
Question: One of the following is true with respect to AUG
a) All of the above
b) It codes for methionine in both prokaryotes and eukaryotes
c) It is also an initiation codon
d) It codes for methionine only
Answer : All of the above
Question: The first genetic material could be
a) RNA
b) DNA
c) carbohydrates
d) protein
Answer : RNA
Question: With regard to mature mRNA in eukaryotes
a) exons appear but introns do not appear in the mature RNA
b) exons and introns do not appear in the mature RNA
c) introns appear but exons do not appear in the mature RNA
d) both exons and introns appear in the mature RNA
Answer : exons appear but introns do not appear in the mature RNA
Question: The human chromosome with the highest and least number of genes in them are respectively
a) Chromosome 1 and Y
b) Chromosome 1 and X
c) Chromosome X and Y
d) Chromosome 21 and Y
Answer : Chromosome 1 and Y
Question: Who amongst the following scientists had no contribution in the development of the double helix model for the structure of DNA?
a) Meselson and Stahl
b) Erwin Chargaff
c) Maurice Wilkins
d) Rosalind Franklin
Answer : Meselson and Stahl
Question: DNA is a polymer of nucleotides which are linked to each other by 3’-5’ phosphodiester bond. To prevent polymerisation of nucleotides, which of the following modifications would you choose?
a) Remove/Replace 3' OH group in deoxy ribose
b) Remove/Replace 2' OH group with some other group in deoxy ribose
c) Both ‘B’ and ‘C’
d) Replace purine with pyrimidines
Answer : Remove/Replace 3' OH group in deoxy ribose
Question: Which of the following steps in transcription is catalysed by RNA polymerse?
a) Elongation
b) Initiation
c) Termination
d) All of the above
Answer : Elongation
Question: Control of gene expression takes place at the level of
a) Transcription
b) Translation
c) None of the above
d) DNA-replication
Answer : Transcription
Question: 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?
a) They can act both as activators and as repressors
b) They interact with RNA polymerase but do not affect the expression
c) They only decrease expression
d) They only increase expression
Answer : They can act both as activators and as repressors
Question: Which was the last human chromosome to be completely sequenced:
a) Chromosome 1
b) Chromosome 11
c) Chromosome 21
d) Chromosome x
Answer : Chromosome 1
Question: Which of the following are the functions of RNA?
a) All of the above
b) It is a constituent component of ribosomes
c) It carries amino acids to ribosomes
d) It is a carrier of genetic information from DNA to ribosomes synthesising polypeptides
Answer : All of the above
Question: 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 Chargaff’s rule it can be concluded that:
a) It is single stranded DNA
b) it is a double stranded circular DNA
c) It is a double stranded linear DNA
d) No conclusion can be drawn
Answer : It is single stranded DNA
Question: A bacterium grown over medium having radioactive 35S incorporates radioactivity in
a) carbohydrates
b) proteins
c) DNA
d) RNA
Answer=B
Question: Leading strand during DNA replication is formed
a) continuously.
b) in short segments.
c) first.
d) ahead of replication.
Answer=A
Question: DNA replication is
a) conservative and discontinuous.
b) semi-conservative and semi-discontinuous.
c) semi-conservative and discontinuous.
d) conservative.
Answer=C
Question: Methyl guanosine triphosphate is added at 5' end of hn-RNA in a process of
a) tailing
b) splicing
c) capping
d) None of these
Answer=C
Question: Genetic code is
a) triplet, universal, ambiguous and degenerate.
b) triplet, universal, non-ambiguous and nondegenerate.
c) triplet, universal, non-ambiguous and degenerate.
d) triplet, universal, ambiguous and non-degenerate.
Answer=C
Question: Segments of mRNA removed during splicing are called
a) introns b) exons
c) promotor regions d) integrator regions
Answer=A
Question: Frame shift mutation occurs when
a) base is deleted or added.
b) base is added.
c) base is deleted.
d) anticodons are not present.
Answer=A
Question: Initiation codon of protein synthesis (in eukaryotes) is
a) GUA b) GCA
c) CCA d) AUG
Answer=D
Question: In eukaryotes, mRNA is synthesized with the aid of
a) RNA polymerase III.
b) RNA polmerase II.
c) RNA polymerase I.
d) reverse transcriptase.
Answer=B
Question: Lactose operon produces enzymes
a) b-galactosidase, permease and glycogen synthetase.
b) b-galactosidase, permease and transacetylase.
c) permease, glycogen synthetase and transacetylase.
d) b-galactosidase, permease and phosphoglucose isomerase.
Answer=B
Question: In some viruses, DNA is synthesised by using RNA as template. Such a DNA is called:
a) c DNA
b) r DNA
c) B-DNA
d) A-DNA
Answer: c DNA
Question: The RNA polymerase holoenzyme transcribes:
a) the structural gene and the terminator regions
b) the structural gene only
c) the promoter, and the
d) the promoter, structural gene and the terminator region
Answer: the structural gene and the terminator regions
Question: If the base sequence of a codon in mRNA is 5'-AUG-3', the sequence of tRNA pairing with it must be
a) 5' - CAU - 3'
b) 5' - AUG - 3'
c) 5' - GUA - 3'
d) 5' - UAC - 3'
Answer: 5' - CAU - 3'
Question: The amino acid attaches to the tRNA at its:
a) 3' - end
b) 5' - end
c) Anti codon site
d) DHU loop
Answer: 3' - end
Question: To initiate translation, the mRNA first binds to
a) The smaller ribosomal sub-unit
b) The larger ribosomal sub-unit
c) The whole ribosome
d) No such specificity exists
Answer: The smaller ribosomal sub-unit
Question: In E.coli, the lac operon gets switched on when
a) lactose is present and it binds to the repressor
b) repressor binds to operator
c) RNA polymerase binds to the operator
d) lactose is present and it binds to RNA polymerase
Answer: lactose is present and it binds to the repressor
Question: The nucleic acid synthesis takes place in
a) 5’-3’ direction
b) 3’-5’ direction
c) Both ways
d) Any direction
Answer: 5’-3’ direction
Question: What is the nature of the strands of the DNA duplex?
a) Anti-parallel and complementary
b) Identical and complementary
c) Anti=parallel and non-complementary
d) Dissimilar and non-complementary
Answer: Anti-parallel and complementary
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MCQs for Chapter 5 Molecular Basis of Inheritance Biology Class 12
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Chapter 5 Molecular Basis of Inheritance NCERT Based Objective Questions
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