PM SHRI JAWAHAR NAVODAYA VIDYALAYA
KALANDRI (SIROHI)
Time allowed : 3 hours Maximum
Marks : 70
General Instructions :
(i) There are a total of 26 questions and five sections in the
question paper.
All questions are compulsory
.
(ii) Section A contains questions number 1 to 17, multiple choice
type
questions of 1 mark each.
(iii) Section B contains questions number 18 to 22, very short
answer type
Questions of 2 mark each.
(iv) Section C contains questions number 23 to 29, short answer
type
questions of 3 marks each.
(v) Section D contains question number 30 to 32 long-answer
question of 4
marks.
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(vi) Section E contains questions number 33 to 34, case based
type
Questions of 5 marks each.
SECTION – A
1. Spliceosomes are absent in the cells of
a. Plants
b. Animals
c. Bacteria
d. Fungi
2. Which of the options has correct identification of 'P', 'Q' and 'R' in the illustration of 'Central
Dogma' given below ?
(A) P-Replication, QrRNA, R-Transcription
(B) P-Translation, Q-mRNA, R-Transcription
(C) P-Replication, Q-mRNA, R-Translation
(D) P-Transcription, Q-mRNA, R-Translation
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3. The primary control of gene expression takes place at the level of
a. Translation
b. Replication
c. Transcription
d. None
4. What will the amount of guanine in a DNA if the total amount of adenine and thiamine in the
DNA is 45%?
a. 45%
b. 65%
c. 27.5%
d. 22.3%
5. The fact that a purine base always pairs through hydrogen bonds with
a pyrimidine base in the DNA double helix leads to:
a. the antiparallel nature
b. the semiconservative nature
c. uniform width throughout DNA
d. uniform length in all DNA
6. The net electric charge on DNA and histones is:
a. both positive
b. both negative
c. negative and positive, respectively
d. zero
7. 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
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c. the 5′ (upstream) end
d. the 3′ (downstream) end
8. Which of the following statements is the most appropriate for sickle cell anemia?
a. It cannot be treated with iron supplements
b. It is a molecular disease
c. It confers resistance to acquiring malaria
d. All of the above
9. The nucleic acid synthesis takes place in
a. 3’-5’ direction
b. 5’-3’ direction
c. Both ways
d. Any direction
10. The process of RNA splicing shows the dominance of
a. RNA world
b. DNA world
c. Microbial world
d. Protein world
.
11. Who amongst the following scientist had no contribution in the development of the double helix
model for the structure of DN A ?
(a) Rosalind Franklin
(b) Maurice Wilkins
(c) Erwin Chargaff
(d) Meselson and Stahl
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12. Which of the following steps in transcription is catalysed by RNA polymerase ?
(a) Initiation
(b) Elongation
(c) Termination
(d) All of the above
13. Assertion : If each strand from a parental DNA acts as template for synthesis of a new
strand, the two double stranded daughter DNA thus produced would be
indentical to th parental DNA molecule.
Reason : The length of DNA double helix in a typical mammalian cell is calculate simply by
multiplying the total number of bp with distance two consecutive bp.
14 .Assertion :DNase is the DNA digestive enzyme
Reason :DNAs represent different type of DNA like ZDNA ,BDNA,ADNA etc.
15. Assertion : Transforming substances was not a protein or RNA.
Reason :Proteases and RNAses do not affect transformation.
16. Assertion : The two chains of DNA have anti-polarity.
Reason: In one chain of DNA ribose sugar at 5’-end consist of a free phosphate moiety while
at the other end the ribose has a free 3’-OH group
17. Assertion: Scaffold proteins are nonhistone chromosomal proteins.
Reason: They are rich in lysine and arginine.
SECTION – B
18. Name any three viruses with RNA as the genetic material.
19. The sequence of the coding strand of DNA in a transcription unit is mentioned below.
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3′3′AATGCAGCTATTAGG
AATGCAGCTATTAGG5′
5′
Write the sequence for:
1. Its complementary strand
2. Its mRNA
20. Retroviruses do not follow central dogma.Comment on this statement
21. Explain about the dual polymerase present in E.coli.
22. What is the difference between heterochromatin and euchromatin?
SECTION – C
23 . Enumerate the post-transcriptional modifications in a eukaryotic mRNA.
24 . What is an operon? Explain an inducible operon.
25. How did Hershey and Chase differentiate between DNA and protein in their experiment
while proving that DNA is the genetic material?
26. Give two reasons why both the strands of DNA are not copied during transcription.
27. “DNA polymerase plays a dual function during DNA replication” comment on the
statement?
28. Explain the process of DNA replication.
29. A structural gene has two DNA strands X and Y shown along side. Identify the template
strand.
SECTION – d
30. What is meant by semi-conservative replication? How did Meselson and Stahl prove it
experimentally?
31. What is DNA fingerprinting? Mention its application.
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32. In the medium where E. coli was growing, lactose was added, which induced the lac
operon. Then, why does lac operon shut down some time after addition of lactose in the
medium?
SECTION – e
33.A DNA replication fork is shown above. Answer the following questions based on
that.
(i) Why does DNA replication occur in
such small forks?
(ii) What is a synthesis and b
synthesis?
(iii) Mention the polarity at A and B.
34. A particular stage in the transcription of a bacterium is given above. Answer the
following questions:
(a) Name the stage in the process.
(b) Identify A, B, C, D and E in the diagram.
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OR
A hypothetical mRNA with 12 codons is shown above.
(a) How many amino acids will be coded by this? Justify your answer.
(b) Mention the dual functions of the codon, AUG.
