Category: IIT JAM Biotechnology Previous Year Question paper Topic Molecular Biology

Category: IIT JAM Biotechnology Previous Year Question paper Topic Molecular Biology

IIT JAM Biotechnology Previous Year Question paper Topic Molecular Biology

40. Assertion [A]: lac operon is an inducible operon. Reason [R]: lac operon is not induced when the repressor protein remains bound to the operator DNA sequence.                                         (A) Both [a] and [r] are true and [r] is the correct reason for [a] (B) Both [a] and [r] are true but [r] is not the correct reason for [a] (C) Both [a] and [r] are false (D) [a] is true but [r] is false

Why Is the Lac Operon an Inducible Operon?

39. Match the RNAs in Group I with their corresponding function in Group II.  Group I Group II (P) snRNA (1) rRNA processing (Q) piRNA (2) RNA splicing (R) snoRNA (3) Selected mRNA degradation (S) siRNA (4) Germ-line protection from transposable elements (A) P-4, Q-3, R-2, S-1 (B) P-4, Q-1, R-3, S-2 (C) P-3, Q-2, R-1, S-4 (D) P-2, Q-4, R-1, S-3

Match snRNA, piRNA, snoRNA and siRNA

38. Which one of the following σ (sigma) factors is responsible for the transcriptional regulation of nitrogen assimilation?     (A) σ70 (B) σ54 (C) σ28 (D) σ24

Transcriptional Regulation of Nitrogen Assimilation

37. In the genetic code, 61 codons code for 20 amino acids. How many types of aminoacyl tRNA synthetases are required for correct matching of tRNAs to their corresponding amino acids?  (A) 61 (B) 64 (C) 40 (D) 20

How Many Types of Aminoacyl-tRNA Synthetases

36. Which one of the following is NOT TRUE of RNA polymerase II?     (A) It requires a primer to initiate the transcription (B) It makes an RNA copy of only one strand of a double-stranded DNA at any given time (C) It does not synthesize rRNA and tRNA (D) It catalyzes the polymerization of RNA only in the 5'→3' direction

Which Statement Is Not True of RNA Polymerase II?

35. Which part of the genomic DNA contains the sequence corresponding to the 5' untranslated region (5' UTR)?     (A) Exon          (B) Intron (C) Upstream of the transcription start site (D) Upstream of the promoter

Which Part of Genomic DNA Contains the Sequence

34. Identify the statement that is TRUE of operons. (A) Fine regulation of the expression of individual genes are made possible by operons (B)Only genes involved in carbohydrate metabolism are present in operons (C) Feedback inhibition of the biosynthesis of multiple enzymes by a single small molecule is made possible by operons (D) In the case of inducible operons, the inducer binds to the operator

Which Statement Is True of Operons?

33.  A 152 nm long Watson-Crick double helical DNA (B-DNA) will contain_____turns.

How Many Turns Are Present in a 152 nm Long Watson-Crick

32. Match the entries in Group I with the entries in Group II     Group I                         Group II DNA replication           1) Hershey and Chase Genetic Code                2) Miller and Urey Life on Earth                3)Messelson and Stahl DNA as Genetic           4) Nirenberg and Khorana Material                (A) P-2, Q-1, R-3, S-4    (B) P-4, Q-3, R-2, S-1 (C) P-3, Q-4, R-2, S-1     (D) P-3, Q-4, R-1, S-2

Match DNA Replication, Genetic Code, Life on Earth and DNA

31. In bacteria, a ribosome synthesizes a protein containing 300 amino acids from mRNA in 20 seconds. If the average lifetime of a mRNA is 2 minutes, the number of ribosomes that can translate a single mRNA containing 1350 nucleotides is

How Many Ribosomes Can Translate a Single Bacterial mRNA

30. Which of the following is(are) INCORRECT in the regulation of the trp operon?  (A) It is an example of a negatively controlled repressible operon (B) The amino acid Trp inactivates the repressor (C) The amino acid Trp induces the operon (D) The repressor binds to the operator in the presence of amino acid Trp

Which Statements Are Incorrect in the Regulation

29. Which of the following is true of protein synthesis ONLY in prokaryotes?     (A)Translation and transcription are coupled (B)The codon AUG codes for the start signal (C)The tRNA anticodon can bind to two or more different codons (D)The functional ribosomes contain two subunits constructed of proteins and RNA

Which Feature of Protein Synthesis Occurs Only in Prokaryotes?

28. Which of the following is NOT involved in eukaryotic translation?   (A) Ribosome   (B) Spliceosome (C) mRNA (D) tRNA

Which Component Is Not Involved in Eukaryotic Translation?

27. In a double stranded DNA, which of the following ratios is/are always equal to 1? A, T, G and C denote the number of bases.     (A) (A+T)/(G+C)           (B) (A+G)/(T+C)           (C) A/G (D) (G+T)/(A+C)

Which Base Ratios Are Always Equal to 1

26. When bacteria are grown in glucose-depleted media containing high concentration of lactose, expression of lac operon genes is activated by (A) the binding of lac repressor in the operator site and cAMP-CAP complex in the CAP site. (B) the dissociation of bound lac repressor from the operator site and binding of cAMP-CAP complex in the CAP site. (C) the dissociation of bound lac repressor only from the operator site. (D) the dissociation of both bound lac repressor from operator site and cAMP-CAP complex from CAP site.

Lac Operon Activation in Glucose-Depleted and Lactose

25. Pick the correct statement(s) with respect to the inter-conversion of the topoisomers of a circularly closed double stranded DNA.  (A) Only one strand needs to be cut (B) Both strands have to be cut (C) No strand needs to be cut (D) ATP is required for inter-conversion

Interconversion of DNA Topoisomers

24. A mutation in the operator locus of lac operon that confers constitutive expression of β- galactosidase is .  (A) cis dominant (B) trans dominant         (C) co-dominant (D) dominant negative

Why Is a Lac Operator Mutation

23. A cDNA was synthesized from the mRNA of a eukaryotic gene. After cloning and sequence analysis, the double-stranded cDNA of 614 bp revealed 125 bp 5′-UTR and 120 bp 3′-UTR. The number of amino acids present in the polypeptide encoded by this gene is _____________. (answer in integer)                    

How to Calculate the Number of Amino Acids

22. Which of the following statement(s) is/are CORRECT for lac repressor expressed from the lacI gene?     (A) The lac repressor is allosterically controlled and it binds to lac operator  (B) The gene lacI is in the 'cis' configuration with respect to lac operon  (C) The presence of glucose weakens the binding of lac repressor to lac operator  (D) The lac repressor regulates 'in trans' the expression of a gene cloned under the control of lac promoter

Lac Repressor and lacI Gene Explained

21. Which of the following statement(s) is/are CORRECT about 'stringent response' in bacteria? (A) It is linked to reduced growth rate  (B) Guanosine tetraphosphate (ppGpp) alone is sufficient to trigger the process  (C) Both guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp) are required to trigger the process  (D) RelA and/or SpoT are/is involved in triggering the process

Stringent Response in Bacteria

20. The 5′ cap of eukaryotic mRNAs contains (A) a modified guanine nucleotide  (B) a modified adenine nucleotide  (C) a modified cytosine nucleotide  (D) a modified uracil nucleotide

What Does the 5′ Cap of Eukaryotic mRNA Contain?

19. The first evidence of 'gene transfer' was demonstrated in 1928 by     (A) Joshua Lederberg in Escherichia coli  (B) Frederick Griffith in Streptococcus pneumoniae  (C) Joshua Lederberg in bacteriophages  (D) Alexander Fleming in Penicillium notatum

First Evidence of Gene Transfer in 1928

18. Which of the following statement(s) about eukaryotic DNA topoisomerase is/are correct? (A) Topoisomerase I creates transient single-strand breaks (B) Topoisomerase I creates transient double-strand breaks (C) Topoisomerase II creates transient single-strand breaks (D) Topoisomerase II creates transient double-strand breaks

Topoisomerase I vs Topoisomerase II

17. Adenine constitutes 0.16 mole fraction in a given single-stranded DNA. What is the mole fraction of uracil in the resultant RNA, if this entire DNA fragment is transcribed?  (A) 0.16 (B) 0.32 (C) 0.34 (D) 0.68

Adenine in DNA and Uracil in RNA Mole Fraction

16. Which one of the following has a catalytic RNA?  (A) Ribonuclease H (B) Ribozyme (C) RNA polymerase I (D) RNA polymerase II

Which One Has Catalytic RNA?

15. In DNA replication, the Okazaki fragments are joined by  (A) DNA helicase (B) DNA ligase (C) DNA polymerase (D) DNA primase

Which Enzyme Joins Okazaki Fragments?

14. The rate of transcription in a bacterium is 50 nucleotides/min and the average molecular weight of an amino acid is 110 Da. Time taken for synthesis of the mRNA of a protein with molecular weight 110 kDa is ______ min (rounded off to one decimal place). 

Calculate Time Required for mRNA Synthesis

13. Match the following  Group I Group II P) Mismatch repair 1. DNA glycosylase Q) Base excision repair 2. UvrA, UvrB, UvrC and UvrD R) Nucleotide excision repair 3. RecA S) Double strand break repair 4. MutL, MutS and MutH (A) P-4, Q-1, R-3, S-2 (B) P-4, Q-2, R-1, S-3 (C) P-4, Q-1, R-2, S-3 (D) P-2, Q-1, R-4, S-3  

DNA Repair Mechanisms Matching

12. Which one of the following is transcribed by RNA polymerase III in eukaryotes?  (A) 18S rRNA (B) 28S rRNA (C) miRNA (D) tRNA

RNA Polymerase III Transcribes tRNA

11. How many GTP molecules are required for the translocation of tRNA from P site to E site during translation elongation process in bacteria?   

How Many GTP Molecules Are Required

10. A double stranded DNA molecule of total 5000 base pairs long, has a melting temperature of 85°C. What will be the % AT base pairs in this sample? (up to one decimal place)

DNA Melting Temperature (Tm) Calculation

9. In bacteria, the σ factor that plays a major role in transcription during the stationary phase is (A) σ⁷⁰ (B) σ⁵⁴ (C) σ²⁸ (D) σ³²

Stationary Phase Sigma Factor in Bacteria

8. DNA gyrase can (A) cut single-stranded DNA (B) relax supercoiled DNA (C) introduce negative supercoiling in DNA (D) not utilize ATP

DNA Gyrase Functions Explained

7. Which of the following activity is associated with Klenow fragment? (A) 5'-3' exonuclease activity (B) 5'-3' endonuclease activity (C) Polymerase activity (D) 3'-5' endonuclease activity

Klenow Fragment Activities Explained

6. A double helical DNA molecule is composed of 32 mol % of adenosine. The mol % of cytosine in this DNA molecule is ____.

Chargaff’s Rule Numerical

5. The number of polypeptide chains in a core nucleosome is ____.

Number of Polypeptide Chains in a Core Nucleosome

4. The number of triplet codon(s) for methionine is ____.

Methionine Codon Explained

3. Which of the following is/are involved in the initiation of DNA replication? (A) RhoA (B) oriC (C) Sigma factor (D) DnaA

Initiation of DNA Replication

2. Which of the following is/are common to both prokaryotic and eukaryotic gene expression?  (A) Coupled transcription and translation (B) Post-translational modification (C) Genetic code (D) Presence of the sequence TATA in the promoter

Common Features of Prokaryotic and Eukaryotic Gene Expression

1. The lack of linear correlation between the genome sizes and genetic complexities among various species is known as (A) C-value paradox (B) Genetic diversity (C) G-value paradox (D) Central dogma

C-Value Paradox Explained

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