Please refer to Chapter 6 Molecular Basis of Inheritance MCQ Class 12 Biology with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 12 Biology. Students should refer to MCQ Questions for Class 12 Biology with Answers to score more marks in Grade 12 Biology exams. Students should read the chapter Molecular Basis of Inheritance and then attempt the following objective questions.

MCQ Questions Class 12 Biology Chapter 6 Molecular Basis of Inheritance

The Molecular Basis of Inheritance MCQ Class 12 Biology provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. What was the finding of Hershey and Chase?             
(a) The viral infecting agent is RNA.
(b) The viral infecting agent is DNA.
(c) The viral infecting agent is protein.
(d) The T2 virus has RNA as its genetic material.

Question. Triplet codon refers to sequence of three bases oh           
(a) tRNA
(b) rRNA
(c) mRNA
(d) alil of these

Question. The functional unit of gene that specifies synthesis of one polypeptide is           
(a) muton
(b) recon
(c) cistron
(d) codon

Question. Hydrogen bonds occur between which of the following constituents of DNA?
(a) sugar and base
(b) phosphate and base
(c) complementary bases
(d) phosphate and sugar

Question. Which one is correct?               
(a) DNA replication occurs before mitosis, meiosis and amitosis.
(b) The polarity of DNA template on which leading strand forms is 3′ —» 5′.
(c) The products of gene may be rRNA, tRNA and mRNA.
(d) All of the above

Question. A large cluster of ribosomes is called         
(a) megasome
(b) microsome
(c) oligosome
(d) polyribosome

Question. Which of the following RNA polymerase catalyses the formation of transfer RNA in eukaryotes? 
(a) RNA polymerase I
(b) RNA polymerase II
(c) RNA polymerase I and II
(d) RNA polymerase III

Question. Part of DNA which switch their positions are called           
(a) cistrons
(b) transposons
(c) exons
(d) introns

Question. Transcription refers to the                 
(a) transfer of genetic code or sequences of DNA into RNA
(b) formation of DMA from RNA
(c) formation of protein
(d) polymerisation of RNA in cell-free system

Question. DNA is present in             
(a) mitochondria
(b) nucleus
(c) chloroplast
(d) All of these

Question. DNA duplex shows           
(a) left handed and parallel coiling
(b) left handed and antiparailel coiling
(c) right handed and parallel coiling
(d) right handed and antiparailel coiling

Question. Isotopes used in proving semiconservative replication of DNA were           
(a) 14N14C
(b) 14N15N
(c) 14N 31P
(d) 14C31P

Question. Bacterial nucleoid has                   
(a) one single-stranded DNA
(b) one double-stranded DNA
(c) two single-stranded DNA
(d) many double-stranded DNAs

Question. The transforming substance of pneumococcus in Griffith’s experiment was
(a) protein
(b) RNA
(c) DNA
(d) polysaccharide

Question. One gene one enzyme hypothesis was proposed by         
(a) Jacob and Monod
(b) Watson and Crick
(c) Garrod and Jenson
(d) Beadle and Tatum

Question. Nucleotide base present in DNA and not in RNA is       
(a) cytosine
(b) thymine
(c) uracil
(d) guanine

Question. Information transfer from RNA to DNA is called     
(a) replication
(b) reverse transcription
(c) translation
(d) transcription

Question. Ligase is an enzyme required for         
(a) proofreading
(b) joining DNA bits
(c) breaking of DNA
(d) renaturation of DNA

Question. Generally only one strand of DNA is transcribed. This strand is called       
(a) A strand
(b) B strand
(c) sense strand
(d) template strand

Question. The chain initiating codon is             
(a) AUG
(b) UAG
(c) UAA
(d) UUA

Question. Out of 64 codons how many of them code for amino acids?             
(a) §4
(b) 20
(c) 61
(d) 32

Question. The difference in A, B and Z forms of DNA lie in       
(a) base sequences’
(b) parallelism of chains
(c) hydrogen bonding
(d) internucleotide distances

Question. In 1928 Frederick Griffith showed that the hereditary material can pass from one type of bacteria into another through a process called   
(a) transduction
(b) invasion
(c) recombination
(d) transformation

Question. DNA replication requires       
(a) DNA polymerase only
(b) DNA ligase only
(c) RNA polymerase and translocase
(d) DNA polymerase and DNA ligase

Question. In 1868 DNA was discovered by the Swedish biochemist             
(a) Feulgen
(b) Luria
(c) Mirsky
(d) Friedrich Miescher

Question. Which one of the following synthesizes a represser protein?               
(a) Regulator gene
(b) Promoter gene
(c) Structural gene
(d) Operator gene

Question. The terms cistron, recon and muton were proposed by         
(a) Benzer
(b) Morgan
(c) Lederberg
(d) Johansen

Question. Enzyme required for transcription is             
(a) DNA polymerase
(b) RNA polymerase
(c) RNA-ase
(d) endonuciease

Question. Synthesis of DNA from RNA template occurs in             
(a) reovirus
(b) rous sajcoma virus
(c) T2
(d) TMV

Question. Watson and Crick proposed the model of DNA structure in               
(a) 1943
(b) 1953
(c) 1963
(d) 1965

Question. How many pairs nucleotides are present in one turn of DNA helix?     
(a) 4
(b) 8
(c) 9
(d) 10

Question. If in a DNA molecule cytosine is 18%, the percentage of adenine would be             
(a) 18%
(b) 32%
(c) 36%
(d) 64%

Question. RNA that picks up specific amino acid from amino acid pool of cytoplasm to carry it to ribosome during protein synthesis is             
(a) mRNA
(b) TRNA
(c) RRNA
(d) gRNA

Question. Initiation of polypeptide chain takes place through         
(a) methionine
(b) lysine
(c) leucine
(d) glycine

Question. Genetic code translates the languages           
(a) RNA into that of protein
(b) RNA into that of DNA
(c) amino acids into that of RNA
(d) protein into that of DNA

Question. Regulator gene controls chemical synthesis (operon system) by           
(a) inhibiting substrate enzyme action
(b) inhibiting transcription of mRNA
(c) inhibiting passage of mRNA
(d) inhibiting enzymes

Question. Which one is not applicable in respect of genetic code?                   
(a) Overlapping
(b) Redundancy
(c) Degeneracy
(d) University

Question. The chain-terminating codon is                   
(a) AUG
(b) CCC
(c) UAG
(d) GGG

Question. In operon model, RNA polymerase binds to               
(a) structural gene
(b) operator gene
(c) promoter gene
(d) regulator

Question. Nonsense codon is responsible for         
(a) elongation of polypeptide chain
(b) termination of protein synthesis
(c) putting a wrong amino acid
(d) hydrolysis of GTP

Question. In one strand of DNA the sequence of bases is AAATGGCCCTT, then the complementary sequence of bases on the other side of the strand would be                 
(a) ATATGGCCCCA
(b) TTTACCGGGAA
(c) TTTTGGCCAM
(d) TTTTGGCCCAA

Question. In bacterial chromosome   
(a) there is one origin of replication
(b) there are multiple sites of replication
(c) there is no repair of DNA
(d) replication is very slow;

Question. Experimental evidence supporting concept of triplet genetic code was first provided by         
(a) Watson
(b) Crick
(c) Michaelis and Menten
(d) Beadle and Tatum

Question. The site of tRNA that binds to mRNA is             
(a) codon
(b) anticodon
(c) 5’ end
(d) 3’ end

Question. In 1957, Meselson and Stahl concluded from their studies that           
(a) DNA replicates conservatively
(b) DNA replicates semiconservatively
(c) DNA replicates dispersively
(d) DNA does not replicate

Question. What is a codon?,             
(a) a group of three deoxy ribonucl eotides
(b) a group of three ribonucleotides
(c) a unit of mutation
(d) a group of four ribonucleotides

Question. Replication is continuous in                     
(a) the leading strand
(b) the lagging strand
(c) the strand where okazaki fragments are present
(d) both the strands

Question. DNA duplication or multiplication is called       
(a) transcription
(b) translation
(c) transaction
(d) replication.

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