Students are advised to practice the NCERT MCQ Questions for Class 12 Biology Chapter 6 Molecular Basis of Inheritance with Answers Pdf free download is available here. MCQ Questions for Class 12 Biology with Answers are prepared as per the Latest Exam Pattern. Students can solve these Molecular Basis of Inheritance Class 12 MCQs Questions with Answers and assess their preparation level.
Molecular Basis of Inheritance Class 12 MCQs Questions with Answers
Solving the Molecular Basis of Inheritance Multiple Choice Questions of Class 12 Biology Chapter 6 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Molecular Basis of Inheritance Class 12 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 6 Biology Class 12 and cross-check your answers during preparation.
Select the correct answer
Question 1.
Who proved semiconservative mode of DNA replication for the first time in E. coli with the help of N15 heavy nitrogen isotope?
(a) Watson and Crick
(b) Kornberg and Ochova
(c) Messelson and Stahl
(d) Luria and Delbruck
Answer
Answer: (c) Messelson and Stahl
Question 2.
A nucleoside differs from a nucleotide. It lacks the :
(a) base
(b) sugar
(c) phosphate group
(d) hydroxyl group.
Answer
Answer: (c) phosphate group
Question 3.
Both deoxyribose and ribose belong to a class of sugars called :
(a) trioses
(b) hexoses
(c) pentoses
(d) polysaccharides.
Answer
Answer: (c) pentoses
Question 4.
The fact that a purine base always paired through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix :
(a) the antiparallel nature
(b) the semiconservative nature
(c) uniform width throughout DNA
(d) uniform length in all DNA.
Answer
Answer: (c) uniform width throughout DNA
Question 5.
The net electric charge on DNA and histones is :
(a) both positive
(b) both negative
(c) negative and positive, respectively
(d) zero
Answer
Answer: (c) negative and positive, respectively
Question 6.
The promoter site and the terminator site for transcription are located at:
(a) 3’ (downstream) end and 5’ (upstream) end, respectively of the transcription unit
(b) 5’ (upstream) end and 3’ (downstream) end, respectively of the transcription unit
(c) the 5’ (upstream) end
(d) the 3’ (downstream) end.
Answer
Answer: (b) 5’ (upstream) end and 3’ (downstream) end, respectively of the transcription unit
Question 7.
Which of the following statements is the most appropriate for sickle cell anaemia?
(a) It cannot be treated with iron supplements.
(b) It is a molecular disease.
(c) It confers resistance of acquiring malaria.
(d) All of the above.
Answer
Answer: (d) All of the above.
Question 8.
One of the following is true with respect to AUG
(a) It codes for methionine only.
(b) It is also an initiation codon.
(c) It codes for methionine in both prokaryotes and eukaryotes.
(d) All of the above.
Answer
Answer: (d) All of the above.
Question 9.
The first genetic material could be :
(a) protein
(b) carbohydrates
(c) DNA
(d) RNA.
Answer
Answer: (d) RNA.
Question 10.
With regard to mature mRNA in eukaryotes:
(a) exons and introns do not appear in the mature RNA
(b) exons appear but 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
Answer: (b) exons appear but introns do not appear in the mature RNA
Question 11.
The human chromosome with the highest and least number of genes in them are respectively:
(a) Chromosome 21 and Y
(b) Chromosome 1 and X
(c) Chromosome 1 and Y
(d) Chromosome X and Y.
Answer
Answer: (c) Chromosome 1 and Y
Question 12.
Who amongst the following scientists had no contribution in the development of the double helix model for the structure of DNA?
(a) Rosalind Franklin
(b) Maurice Wilkins
(c) Erwin Chargaff
(d) Meselson and Stahl.
Answer
Answer: (d) Meselson and Stahl.
Question 13.
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) Replace purine with pyrimidines
(b) Remove/Replace 3’ OH group in deoxyribose
(c) Remove/Replace 2’ OH group with some other group in deoxyribose
(d) Both ‘B’ and ‘C’.
Answer
Answer: (b) Remove/Replace 3’ OH group in deoxyribose
Question 14.
Which of the following steps in transcription is catalysed by RNA polymerase?
(a) Initiation
(b) Elongation
(c) Termination
(d) All of the above.
Answer
Answer: (b) Elongation
Question 15.
Control of gene expression takes place at the level of:
(a) DNA-replication
(b) Transcription
(c) Translation
(d) None of the above
Answer
Answer: (b) Transcription
Question 16.
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 only increase expression.
(b) They only decrease expression.
(c) They interact with RNA polymerase but do not affect the expression.
(d) They can act both as activators and as repressors.
Answer
Answer: (d) They can act both as activators and as repressors.
Question 17.
Which was the last human chromosome to be completely sequenced :
(a) Chromosome 1
(b) Chromosome 11
(c) Chromosome 21
(d) Chromosome X.
Answer
Answer: (a) Chromosome 1
Question 18.
Which of the following are the functions of RNA ?
(a) It is a carrier of genetic information from DNA to ribosomes synthesising polypeptides.
(b) It carries amino acids to ribosomes.
(c) It is a constituent component of ribosomes.
(d) All of the above.
Answer
Answer: (d) All of the above.
Question 19.
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 a double-stranded circular DNA.
(b) It is a single-stranded DNA.
(c) It is a double-stranded linear DNA.
(d) No conclusion can be drawn.
Answer
Answer: (b) It is a single-stranded DNA.
Assertion and Reason Type Questions
These questions consist of two statements each, printed as Assertion and Reason. While answering these questions you are required to choose any one of the following four responses.
(a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
(c) If Assertion is true but the Reason is false.
(d) If both Assertion and Reason are false.
Question 20.
Assertion: Replication and transcription occur in the nucleus but translation occurs in the cytoplasm.
Reason: mRNA is transferred from the nucleus into the cytoplasm where ribosomes and amino acids are available for protein synthesis.
Answer
Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
Question 21.
Assertion: Amber codon is a termination codon.
Reason: If in an mRNA, a termination codon is present, the protein synthesis stops abruptly whether the protein synthesis is complete or not.
Answer
Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
Question 22.
Assertion: The first codon discovered by Nirenberg and Mathaei was UUU.
Reason: Genetic code translates the language of protein into that of RNA.
Answer
Answer: (d) If both Assertion and Reason are false.
Question 23.
Assertion: For DNA replication RNA primer is needed.
Reason: Synthesis of new DNA chain is initiated by DNA polymerase.
Answer
Answer: (c) If Assertion is true but the Reason is false.
Question 24.
Assertion: One of the properties of genetic code is degeneracy.
Reason: Many amino acids can be coded by more than one codon.
Answer
Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
Question 25.
Assertion: Genetic code shows code in mRNA not in DNA.
Reason: DNA is present inside the nucleus and code is read from mRNA inside the cell.
Answer
Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
Question 26.
Assertion: DNA molecule acts as a template for synthesis of both RNA and DNA.
Reason: DNA duplex has the feature of right-handed coiling and antiparallel.
Answer
Answer: (b) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
Question 27.
Assertion: Plasmids are being widely used as vehicle DNA.
Reason: They can be easily isolated and introduced as viral genome.
Answer
Answer: (a) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
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