Biology - Molecular Basis of Inheritance Multiple Choice Questions (MCQs) for Class 12 NCERT

106 The RNA polymerase holoenzyme transcribes:

1 the promoter, structural gene and the terminator region

2 the promoter, and the

3 the structural gene and the terminator regions

4 the structural gene only.

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Answer: the structural gene and the terminator regions

107 To initiate translation, the mRNA first binds to:

1 The smaller ribosomal sub-unit

2 The larger ribosomal sub-unit

3 The whole ribosome

4 No such specificity exists.

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Answer: The smaller ribosomal sub-unit

108 Repressor proteins are coded for by ______ genes.

1 Structural

2 Operator

3 Promoter

4 Regulator

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Answer: Regulator

109 The organelles in the cell where protein synthesis occurs are ______.

1 Endoplasmic reticulum

2 lNuceus

3 Ribosomes

4 mRNA

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Answer: Ribosomes

110 PCR and Restriction Fragment Length Polymorphism are the methods fo

1 DNA sequencing

2 Genetic fingerprinting

3 Study of enzymes

4 Genetic transformation

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Answer: Genetic fingerprinting

111 What is antisense technology?

1 RNA polymerase producing DNA

2 A cell displaying a foreign antigen used for synthesis of antigens

3 Production of somaclonal variants in tissue cultures

4 When a piece of RNA that is complementary in sequence is used to stop expression of a specific gene

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Answer: When a piece of RNA that is complementary in sequence is used to stop expression of a specific gene

112 A DNA segment which serves as a kind of “on-off switch” for transcription is a/an ______.

1 Regulator gene

2 Structural gene

3 Promoter

4 Operator

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Answer: Operator

113 Which one of the following does not follow the central dogma of molecular biology?

1 Pea

2 Mucor

3 HIV

4 Chlamydomonas

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Answer: HIV

114 In some viruses, DNA is synthesised by using RNA as template. Such a DNA is called

1 A-DNA

2 B-DNA

3 c DNA

4 r DNA

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Answer: c DNA

115 Discontinuous synthesis of DNA occurs in one strand, because:

1 DNA molecule being synthesised is very long

2 DNA dependent DNA polymearse catalyses polymerisation only in one direction (5’ → 3’)

3 it is a more efficient process

4 DNA ligase has to have a role

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Answer: DNA dependent DNA polymearse catalyses polymerisation only in one direction (5’ → 3’)

116 Both deoxyribose and ribose belong to a class of sugars called:

1 trioses

2 hexoses

3 pentoses

4 polysaccharides

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Answer: pentoses

117 Which of the following statements is the most appropriate for sickle cell anaemia?

1 It cannot be treated with iron supplements

2 It is a molecular disease

3 It confers resistance to acquiring malaria

4 All of the above

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Answer: All of the above

118 Who amongst the following scientists had no contribution in the development of the double helix model for the structure of DNA?

1 Rosalind Franklin

2 Maurice Wilkins

3 Erwin Chargaff

4 Meselson and Stahl

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Answer: Meselson and Stahl

119 Which of the following steps in transcription is catalysed by RNA polymerse?

1 Initiation

2 Elongation

3 Termination

4 All of the above

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Answer: Elongation

120 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:

1 it is a double stranded circular DNA

2 It is single stranded DNA

3 It is a double stranded linear DNA

4 No conclusion can be drawn

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