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NEET Biology MCQ
Molecular Basis Of Inheritance Mcq
Quiz 1
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Q.1
The specific palindromic sequence which is recognized by EcoRI is ... [ NEET 2021]
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a) 5' - CTTAAG - 3' 3' - GAATTC - 5'
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b) 5' - GGATCC - 3' 3' - CCTAGG - 5'
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c) 5' - GAATTC - 3' 3' - CTTAAG - 5'
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d) 5' - GGAACC - 3' 3' - CCTTGG - 5'
Explanation
palindromes are groups of letters that form the same words when read both forward and backward, sequences reads 5' - GAATTC - 3' 3' - CTTAAG - 5' the same on the two strands in 5' → 3' direction. This is also true if read in the 3' → 5' direction. Answer : (c)
Q.2
Purines found both in DNA and RNA are ....[NEET 2019]
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a) Adenine and thymine
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b) Adenine and guanine
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c) Guanine and cytosine
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d) Cytosine and thymine
Explanation
Purines found both in DNA and RNA are Adenine and guanine Answer : (d)
Q.3
Variations caused by mutation, as proposed by Hugo de Vries are .... [ NEET 2019]
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a) random and directional
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b) random and directionless
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c) small and directional
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d) small and directionless
Explanation
According to Hugo de Vries, mutations are random and directionless. Devries believed mutation caused speciation and hence called saltation (single step large mutation). Answer : (b)
Q.4
Expressed Sequence Tags (ESTs) refers to : [NEET 2019]
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a) Genes expressed as RNA
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b) Polypeptide expression
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c) DNA polymorphism
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d) Novel DNA sequences
Explanation
Expressed Sequence Tags (ESTs) are DNA sequences (genes) that are expressed as mRNA for protein synthesis. These are used in human Genome Project. Answer : (a)
Q.5
atch the following genes of the Lac operon with their respective products : Select the correct option. [ NEET 2019]
(a) i gene
(i) β-galactosidase
(b) z gene
(ii) Permease
(c) a gene
(iii) Repressor
(d) y gene
(iv) Transacetylase
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a) a → i; b → iii; c → ii; d → iv;
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b) a → iii; b → i; c → ii; d → iv;
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c) a → iii; b → i; c → iv; d → ii;
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d) a → iii; b → iv; c → i; d → ii;
Explanation
In lac operon i gene → Repressor z gene → β-galactosidase y gene → Permease a gene → Transacetylase Answer : (c)
Q.6
Under which of the following conditions will there be no change in the reading frame of following mRNA? 5'AACAGCGGUGCUAUU3' [NEET 2019]
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a) Insertion of G at 5th position
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b) Deletion of G from 5th position
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c) Insertion of A and G at 4th and 5th positions respectively
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d) Deletion of GGU from 7th, 8th and 9th positions
Explanation
Deletion of three bases delets a codon and reading frame remains unaltered from that point onwards. No change in reading frame of m-RNA. Answer : (d)
Q.7
The experimental proof for semiconservative replication of DNA was first shown in a ... ..[NEET 2018]
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a) Plant
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b) Bacterium
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c) Fungus
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d) Virus
Explanation
It is now proven that DNA replicates semiconservatively. It was shown first in Escherichia coli. Answer : (b)
Q.8
Select the correct match :
(1)Matthew Meselson and F. Stahl
Pisum sativum
(2)Alfred Hershey and Martha Chase
TMV
(3)Alec Jeffreys
Streptococcus pneumoniae
(4)Francois Jacob and Jacques Monod
Lac operon
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a) 1st
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b) 2nd
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c) 3rd
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d) 4th
Explanation
The Meselson–Stahl experiment is an experiment by Matthew Meselson and Franklin Stahl in 1958 which supported Watson and Crick's hypothesis that DNA replication was semiconservative. The experiment was done using E.coli. Hence option (a) is not correct match. The Hershey–Chase experiments were a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase that helped to confirm that DNA is genetic material. Bacteriophage was used for the experiment, not TMV. So option (b) is not correct match. Jeffreys had a "eureka moment" in his lab in Leicester after looking at the X-ray film image of a DNA experiment on 10 September 1984, which unexpectedly showed both similarities and differences between the DNA of different members of his technician's family. So option (c) is not correct match. Jacob and Monod discovered that a protein, which they called lac repressor, binds to the gene that produces the required metabolic enzyme and suppresses the gene's transcription and translation when lactose is not present in the environment. So option (d) is correct match. Answer : (d)
Q.9
All of the following are part of an operon except ... ..[NEET 2018]
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a) an enhancer
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b) structural genes
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c) an operator
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d) a promoter
Explanation
In bacteria, more than one gene is arranged together and regulated in units called as operons. Each operon has its specific operator and specific repressor. The lac operon consists of one regulatory gene (the i gene – here the term i does not refer to inducer, rather it is derived from the word inhibitor) and three structural genes (z, y, and a). Enhancer: The binding of these proteins will enhance the transcription of an associated gene. They are not the part of the operon structure. Answer : (a)
Q.10
According to Hugo de Vries, the mechanism of evolution is ... [NEET 2018]
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a) Phenotypic variations
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b) Saltation
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c) Multiple step mutations
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d) Minor mutations
Explanation
Hugo deVries based on his work on evening primrose brought forth the idea of mutations – large difference arising suddenly in a population. He believed that it is mutation which causes evolution. deVries believed mutation caused speciation and hence called it saltation (single step large mutation) Answer : (b)
Q.11
The diagram shows an important concept in the genetic implication of DNA. Fill in the blanks A to C …[NEET 2013]
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a) A-transcription, B-replication, C-James Watson
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b) A-translation, B-transcription, C-Erevin Chargaff
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c) A-transcription, B-translation, C-Francis Crick
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d) A-translation, B-extension, C-Rosalind Franklin
Explanation
Try again
Q.12
AGGTATCGCAT is a sequence from the coding strand of a gene. What will be the corresponding sequence of the transcribed mRNA ? [NEET 2018]
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a) ACCUAUGCGAU
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b) UGGTUTCGCAT
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c) AGGUAUCGCAU
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d) UCCAUAGCGUA
Explanation
Coding strand and mRNA has same nucleotide sequence except, ‘T’ – Thymine is replaced by ‘U’–Uracil in mRNA. Answer : (d)
Q.13
Name the enzyme that facilitates opening of DNA helix during transcription. [NEET 2020]
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a) DNA polymerase
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b) RNA polymerase
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c) DNA ligase
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d) DNA helicase
Explanation
RNA polymerase binds to promoter and initiates transcription (Initiation). Answer : (b)
Q.14
Identify the wrong statement with regard to Restriction Enzymes. [NEET 2020]
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a) They are useful in genetic engineering.
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b) Sticky ends can be joined by using DNA ligases.
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c) Each restriction enzyme functions by inspecting the length of a DNA sequence.
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d) They cut the strand of DNA at palindromic sites.
Explanation
A restriction enzyme is a protein isolated from bacteria that cleaves DNA sequences at sequence-specific sites, producing DNA fragments with a known sequence at each end. DNA ligases are used with restriction enzymes to insert DNA fragments, often genes, into plasmids. DNA ligase is not restriction enzymes. Answer : (b)
Q.15
Which of the following statements is correct?
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a) Adenine pairs with thymine through three H-bonds
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b) Adenine does not pair with thymine
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c) Adenine pairs with thymine through two H bonds
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d)Adenine pairs with thymine through one Hbond
Explanation
Adenine forms two hydrogen bonds with Thymine from opposite strand and vice-versa. Answer : (c)
Q.16
If the distance between two consecutive base pairs is 0.34 nm and the total number of base pairs of a DNA double helix in a typical mammalian cell is 6.6 × 109 bp, then the length of the DNA is approximately
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a) 2.2 meters
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b) 2.7 meters
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c) 2.0 meters
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d) 2.5 meters
Explanation
Length of DNA = Number of base pairs * Distance between two consecutive base pairs length of DNA= 6.6 × 109 bp * 0.34 x 10-9m = 2.24 m Answer : (a)
Q.17
The first phase of translation is ... .. [NEET 2020]
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a) Aminoacylation of tRNA
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b) Recognition of an anti-codon
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c) Binding of mRNA to ribosome
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d) Recognition of DNA molecule
Explanation
in the first phase itself amino acids are activated in the presence of ATP and linked to their cognate tRNA – a process commonly called as charging of tRNA or aminoacylation of tRNA to be more specific. Answer : (a)
Q.18
A ribotide is made of ... ... [ kerala 2004 ]
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a) Adenine + Deoxyribose + Phosphate
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b) Uracil + Ribose + Phosphate
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c) Thymine + Ribose + Phosphate
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d) Uracil + Deoxyribose + Phosphate
Explanation
The general structure of a ribonucleotide consists of a phosphate group, a ribose sugar group, and a nucleobase, in which the nucleobase can either be adenine, guanine, cytosine, or uracil. in which the nucleobase can either be adenine, guanine, cytosine, or uracil. Answer : (b)
Q.19
Which disease is spread by activation of oncogenes? [ MPPMT 1999 ]
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a) Cholera
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b) TB
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c) Cancer
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d) Viral flu
Explanation
An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels. Most normal cells will undergo a programmed form of rapid cell death (apoptosis) when critical functions are altered and malfunctioning. Answer : (c)
Q.20
Find out the mismatch ... ...
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a) Mc Clintock → Jumping genes
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b) Khorana → Mutation induction in Drosophila
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c) Landsteiner → Blood groups
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d) Wallace → Organic evolution
Explanation
In his experiments, Muller exposed fruit flies (Drosophila) to x-rays, mated the flies, and observed the number of mutations in the offspring. His discovery indicated the causes of mutation and for that research he later received the Nobel Prize in Physiology or Medicine in 1946 Answer : (b)
Q.21
Reverse flow of information in central dogma of molecular biology is .... ....
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a) DNA → RNA → Protein
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b) Protein → DNA RNA
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c) mRNA → tRNA → DNA
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d) RNA → DNA → Protein
Explanation
The central dogma of molecular biology describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein. Reverse transcription is the transfer of information from RNA to DNA (the reverse of normal transcription) Answer : (d)
Q.22
Genetic code determines ... .. [ AMU 1999 ]
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a) Sequence of amino acids in protein chain
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b) variations
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c) Constancy of morphological traits
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d) Structural pattern
Explanation
Genetic code, the sequence of nucleotides in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that determines the amino acid sequence of proteins. Answer : (a)
Q.23
Association of mRNA with many ribosomes is ... .. [ WB 2007]
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a) Informosome
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b) Polysome
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c) Kinetochore
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d) Centrosome
Explanation
The group of ribosomes bound to an mRNA molecule is called a polyribosome, or polysome A polyribosome or a polysome is an organization of mRNA molecule attached to two or more ribosomes at the same time in order to speed up the translation process of long mRNA transcripts. Answer : (b)
Q.24
tRNA has two unequal free arms .... .... [ MHTCET 2001 ]
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a) Short arm ending in -G and long arm in -CCA
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b) Short arm ending in -A and long arm in -ACC
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c) Short arm ending in -G and long arm in -CGA
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d) Short arm ending in C and long arm in GCA
Explanation
Answer : (a)
Q.25
What is amino acid sequence encoded by base sequence UCA UUU UCC GGG AGU of mRNA segment? ... .... [ EAMCET 2009 ]
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a) Glycine - Serine - Phenylalanine - Serine - Glycine
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b) Serine - Phenylalanine - Serine - Glycine - Serine
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c) Serine - Phenylalanine - Glycine - Serine - Glycine
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d) Methionine - Phenylalanine - Serine - Glycine - Serine
Explanation
UCA=Serine; UUU=Phenylalanine; UCC=Serine GGG=Glycine AGU=Serine Refer question no 1 answer or NCERT page 112 Table 6.1: The Codons for the Various Amino Acids Answer : (b)
Q.26
Transition mutation is due to replacement of ... .... [ MPPMT 2000 ]
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a) GC by TA
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b) AT by CG
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c) CG by GC
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d) AT by GC
Explanation
Transversion mutation is a specific kind of point mutation, one in which a single purine is substituted for a pyrimidine or vice versa. for example, when a TA or CG pair replaces the wild type AT pair. Answer : (d)
Q.27
Gene does not produce ... ... [ MHTCET 2010 ]
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a) mRNA
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b) Sugar
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c) Polypeptide
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d) Enzyme
Explanation
Gene does not produce sugar Answer : (b)
Q.28
Genetic code is degenerate because .... .. [ AMU 2003 ]
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a) Codons have same energy level
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b) Each codon has a different meaning
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c) Each cogon has many meanings
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d) Many codons have same meaning
Explanation
The genetic code is degenerate because there are many instances in which different codons specify the same amino acid. Answer : (d)
Q.29
A strand of DNA has base sequence CATGACTAG. the base sequence on the other strand would be ... .. [BHU 2001 ]
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a) CAT TAG GAC
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b) GTA CTG ATC
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c) GAT GTC ATC
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d) TAC ACT GCT
Explanation
base pairs arise in complementary strands of DNA: adenine → thymine (A → T) thymine → adenine (T → A) cytosine → guanine (C → G) guanine → cytosine (G → C) CAT GAC TAG other strand would be GTA CTG ATC Answer : (b)
Q.30
Central dogma of molecular biology was modified with the discovery of ... ... [ PMT 2007 ]
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a) Ligase
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b) RNA polymerase
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c) DNA polymerase
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d) Reverse transcriptase
Explanation
The central dogma of molecular biology describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein. A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. The biggest revolution in the central dogma was the discovery of retroviruses, which transcribe RNA into DNA through the use of a special enzyme called reverse transcriptase has resulted in an exception to the central dogma; RNA → DNA → RNA → protein. Answer : (d)
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