II PU BIOLOGY (BOTANY) CET PREPARATORY PAPER
MOLECULAR BIOLOGY – NUCLEIC ACIDS
1. The last three nucleotides at the 3’ end of all tRNA molecules are always -- ----.
1) 5’CCA3’;
2) 3’CCA5’;
3) 5’AAC3’;
4) 3’AAC5’.
2. Choose
1)
2)
3)
4)
the correct statement:
DNA is present in all organisms as the genetic material.
All organisms have RNA as genetic material.
All organisms have both DNA and RNA as genetic material.
RNA becomes genetic material only in the absence of DNA.
3. Choose the correct statement:
1) All nitrogen bases are double-ringed molecules
2) All nitrogen bases are single-ringed molecules
3) Purines are double-ringed and pyrimidines are single-ringed
4) Purines are single-ringed and pyrimidines are double-ringed
4. The following are different types of sugars present in living cells; which of them
is present in DNA?
1) C5H10O5
2) C4H8O4
3) C6H12O6
4) C5H10O4
5. The bond that links two nucleotides in a single strand of DNA is called ----.
1) phosphoanhydride bond
2) 3’-5’- phosphodiester bond
3) 2’ – 5’- phosphodiester bond
4) 5’-3’- phosphodiester bond
6. Who among the following was not a recipient of Nobel Prize for DNA discovery?
1) James Watson
2) Rosalind Franklin
3) Maurice Wilkins
4) Francis Crick
7. Constant nucleotide ratio in DNA was proposed by -----.
1) Watson and Crick
2) Rosalind Franklin
3) Maurice Wilkins
4) Chargaff
8. The nitrogenous base is attached to the ------ carbon of the pentose sugar
component in a nucleotide.
1) first
2) second
3) third
4) fifth
9. One of the following need not be true in DNA:
1) A = T
2) G = C
3) A + G = T + C
4) A + T = G + C
10. One of the following base-pairings does not usually occur in nucleic acids of
living organisms:
1) A = T
2) G Ξ C
3) A = U
4) G Ξ U
11. Identify the correct components of a DNA nucleotide:
1) Adenine + Ribose + Phosphate
2) Adenine + Deoxyribose + Phosphate
3) Adenosine + Ribose + Phosphate
4) Uracil + Deoxyribose + Phosphate
12. A DNA molecule has 100 base pairs. How many phosphodiester bonds are
present in it?
1) 100
2) 200
3) 99
4) 198
13. One of the following characters is usually absent in DNA:
1) constant nucleotide ratio
2) antiparallelism of the two strands
3) true double helix
4) false double helix
2
14. Study the two statements given below and answer the question:
A. DNA molecules are extremely stable
B. There are innumerable H- bonds between the two strands
in DNA.
1) Both statements are correct and B is the reason for A.
2) Both statements are correct but B is not the reason for A.
3) Statement A is correct but B is wrong.
4) Statement A is wrong but B is correct.
15. Identify the double-ringed bases among the following:
1) adenine & thymine
2) cytosine & guanine
3) adenine & cytosine
4) adenine & guanine
16. Choose the correct arrangement of components of a nucleotide of DNA:
1) Adenine – ribose – phosphate
2) Adenine – phosphate – ribose
3) Adenine – deoxyribose – phosphate
4) Adenine – phosphate - deoxyribose
17. Study the two statements given below and answer the question:
A - RNA molecules are usually unstable.
B - RNA molecules are relatively smaller than DNA.
1) Both statements are correct and B is the reason for A.
2) Both statements are correct but B is not the reason for A.
3) Statement A is correct but B is wrong.
4) Statement A is wrong but B is correct.
18. The nucleotide sequence on one strand of DNA is as follows:
5’ AGCTAGCTAAGG 3’
What must be the sequence on the other strand?
1) 5’ AGCTAGCTAAGG 3’
2) 3’ AGCTAGCTAAGG 5’
3) 5’ CCTTAGCTAGCT 3’
4) 3’ CCTTAGCTAGCT 5’
19. A DNA molecule measures about 6.8 mm. What would be the number of
nucleotides in it?
1) 4X108;
2) 4 X107;
3) 2X108;
4) 2X107.
20.
A DNA molecule is 1.7cm long. What is the total number of turns in the
molecule?
1) 5 million 2) 50 million 3) 500,000
4) impossible to calculate.
21. Identify the pair of single-ringed bases among the following:
1) thymine & uracil
2) cytosine & guanine
3) adenine & thymine
4) uracil & adenine
22. In eukaryotic organisms, heterogeneous nuclear RNA (popularly called hnRNA)
is modified to produce ---------:
1) mRNA
2) rRNA
3) tRNA
4) genetic RNA
23. Identify the pyrimidine that is present in both DNA and RNA:
1) adenine
2) guanine
3) cytosine
4) uracil
24. This enzyme is necessary for joining all the Okazaki fragments into a
continuous daughter strand during replication of DNA:
1) primase
2) helicase
3) ligase
4) topoisomerase
25. Discovery of DNA as genetic material was made with reference to the study of
the following phenomenon in bacteria:
1) Conjugation
2) Transduction
3) Recombination
4) Transformation
3
26. If in a DNA molecule there are 322 cytosine nucleotides, ------ nucleotides
must also be 322.
1) Adenine
2) Guanine
3) Cytosine
4) Uracil
27. Which of the following is not a nucleoside?
1) Adenosine 2) Guanosine
3) Uridine
4) Cytosine
28. Energy for replication of DNA is provided by ------.
1) The respective nucleoside triphosphates 2) ATP
3) Free phosphate radicals in the cell
4) The respective nucleotides.
29. The proportion of Thymine nucleotide in a DNA is 42%. What would be the
proportion of Guanine?
1) 42%
2) 8%
3) 16%
4) 84%
30. An organism inherits only this from its parent:
1) mRNA
2) tRNA
3) rRNA
4) DNA
31. One of the following base-pairings does not normally occur during replication
of DNA:
1) new A pairing with T
2) new G pairing with C
3) new U pairing with A
4) new A pairing with U
32. A DNA molecule is 34μm in length; 53% of its base-pairs are G-C; find out the
total number of H-bonds between the two strands in the molecule.
1) 25300
2) 253000
3) 247000
4) 24700
33. Which among the following is the usual site of replication of DNA in a normal
eukaryotic cell?
1) cytoplasm
2) nucleus
3) nucleolus
4) ribosomes
34. Replication of DNA cannot occur in this part of the cell:
1) Lysosomes
2) Mitochondria
3) Chloroplasts
4) Nucleus
35. Replication of DNA always starts in this region:
1) The orisite
2) The operator site
3) The initiator codon of the gene
4) The start site of a gene
36. The most commonly found DNA in living organisms is -------.
1) B-DNA
2) A-DNA
3) C-DNA
4) Z-DNA
37. Which of the following exhibits cDNA formation?
1) lambda phage
2) T even phages
3) E. coli bacteria
4) HIV
38. This DNA has a left-handed helix.
1) B-DNA
2) A-DNA
4) Z-DNA
3) C-DNA
39. The first sample of DNA extracted by Miescher was from ------.
1) Human RBCs
2) Human pus cells
3) Rat liver
4) Thymus gland of cattle
40. Semiconservative method of replication of DNA was discovered by Meselson
and Stahl using for raw materials nucleotide triphosphates in which -------.
1) thymine was labelled with radioactive isotope
2) guanine was labelled with radioactive isotope
3) cytosine was labelled with radioactive isotope
4) adenine was labelled with radioactive isotope
4
41. In a DNA molecule, the pitch of the helix is 34Å, i.e., the molecule completes
one full turn in 34 Å. Therefore, each pair of nucleotides in the DNA is at an
orientation angle of ------ to the next pair.
1) 36o
2) 3.6 o
3) 34 o
4) 3.4 o
42. Synthesis of DNA on a template of RNA strand is also known as -------.
1) RNA splicing;
2) Transcription;
3) DNA repair;
4) Reverse transcription.
43. A molecule of DNA is 2.5kbp long; what would be its absolute length?
1) 850nm
2) 8500nm
3) 850Å
4) 8.5mm
44. In the famous experiment conducted by Avery and others on the smooth
virulent forms of Streptococcus pneumoniae bacteria, the transforming
principle in the bacterial extracts was destroyed by the use of this enzyme:
1) trypsin
2) DNAase
3) lipase
4) RNAase
45. Since DNA is absent, RNA behaves as the genetic material in this group:
1) Prions
2) All viruses
3) Some viruses like the bacteriophage
4) Some viruses like the HIV
46. Unwinding of the DNA at the time of replication is performed by this enzyme:
1) Ligase
2) Primase
3) Toposiomerase
4) Helicase
47. All molecules of DNA except this are produced by another preexisting strand of
DNA:
1) eukaryotic DNA
2) all phage DNA
3) bacterial DNA
4) retroviral DNA
48. Usually RNA molecules do not contain thymine except this type:
1) rRNA
2) mRNA
3) hnRNA
4) tRNA
49. If this part of DNA is damaged it cannot be replicated:
1) restriction site
2) promoter site
3) orisite
4) primer RNA
50. During replication of DNA the new daughter strand of DNA starts actually as a
piece of RNA strand. This is made by this enzyme:
1) ligase
2) primase
3) helicase
4) topoisomerase
51. DNA is not the genetic material in this organism:
1) lambda phage
2) T2 phage
3) TMV
4) adenovirus
52. The phosphate part of a nucleotide is attached to ----- carbon of the pentose
sugar.
1) first
2) second
3) third
4) fifth
53. Which of the following properties is true for RNA?
1) very highly stable
2) it is usually longer than DNA
3) always storing genetic information
4) nucleotide ratio is variable
54. Study the two statements given below and answer the question:
A - The two strands of DNA are held together by innumerable Hbonds.
B - The quantity of DNA in a living cell is usually constant.
1)
2)
3)
4)
Both statements are correct and B is the reason for A.
Both statements are correct but B is not the reason for A.
Statement A is correct but B is wrong.
Statement A is wrong but B is correct.
5
55. The rate of replication of DNA in many cells is about 120 bases per second.
How long does it take for the entire replication to be completed for this
DNA that is 102 nm long?
1) 25 seconds
2) 25 minutes
3) 5 seconds 4) 2.5 seconds
56. The satellite region of SAT chromosome does not contain ------.
1) Both Adenine and Thymine;
2) Only Cytosine;
3) Only Guanine;
4) Both Guanine and Cytosine.
57. The concept of central dogma was proposed by -------.
1) Erwin Chargaff
2) Khorana and others
3) Lederberg & Tatum
4) Watson & Crick
58. Study the two statements given below and answer the question:
A – Replication of DNA is usually very accurate and error-free.
B – DNA polymerases have proof correction ability.
1) Both statements are correct and A is the reason for B.
2) Both statements are correct but A is not the reason for B.
3) Statement A is correct but B is wrong.
4) Statement A is wrong but B is correct.
59. Study the diagram given below and give the correct combination of labels for
the different parts:
1) m-adenine; n-guanine; o-cytosine; p-thymine; x-phosphate; ydeoxyribose.
2) m-adenine; n-cytosine; o-thymine; p-guanine; x-phosphate; ydeoxyribose.
3) m-guanine; n-thymine; o-cytosine; p-adenine; x-phosphate; ydeoxyribose.
4) m-adenine; n-cytosine; o-thymine; p-guanine; x-deoxyribose; yphosphate.
x
o
m
y
n
p
A PORTION OF DNA MOLECULE
6
60. Study the diagram given above and select the correct combination of nucleotides
in the molecule:
1)
AT
CG
AT
TA
GC
2)
GC
TA
GC
CG
AT
3)
4) CG
AT
CG
AT
CG
TA
GC
TA
AT
CG
25th November 2007
This questionnaire was prepared by
DR. B. SHIVASHANKAR
Retd. H.O.D. of BOTANY,
The National College, Basavanagudi,
BANGALORE –560 004
KEY ANSWERS:
1- (1)
6 - (2)
11 - (2)
16 - (3)
21 - (1)
26 - (2)
31 - (4)
36 - (1)
41 - (1)
46 - (4)
51 - (3)
56 - (1)
2- (4)
7 - (4)
12 - (4)
17 - (2)
22 - (1)
27 - (4)
32 - (2)
37 - (4)
42 - (4)
47 - (4)
52 - (4)
57 - (4)
3 - (3)
8 - (1)
13 - (4)
18 - (3)
23 - (3)
28 - (1)
33 - (2)
38 - (4)
43 - (1)
48 - (4)
53 - (4)
58 - (2)
4 - (4)
9 - (4)
14 - (1)
19 - (2)
24 - (3)
29 - (2)
34 - (1)
39 - (2)
44 - (2)
49 - (3)
54 - (2)
59 - (2)
5 - (2)
10 - (4)
15 - (4)
20 - (1)
25 - (4)
30 - (4)
35 - (1)
40 - (1)
45 - (4)
50 - (2)
55 - (3)
60 - (1)