BM SnapTest - I

Molecular Basis of Inheritance

Max Marks – 180 Max Time – 60 mins

Question 1: Which of the following pairs is Options:
incorrectly matched? (a) The DNA backbone is formed of sugar-
Options: phosphate groups, with the nitrogenous
(a) Purines - Adenine and Guanine bases pointing outwards
(b) Pyrimidines - Cytosine and Uracil (b) A large-sized purine always binds to a
(c) Nucleosides - Adenosine and Thymidine small-sized pyrimidine
(d) DNA - Basic biomolecule (c) The two polynucleotide strands make a
right-handed helix
Question 2: What does A and B represent in (d) The two strands are antiparallel to each
the given representation? other

Question 5: If Guanine makes 40% of the

DNA molecule, what will be the
percentage of Thymine (T), Adenine (A),
and Cytosine (C) in it?
Options:
Options: (a) C: 40; A: 30; T: 30
(a) A- Ribonucleoside, B- (b) C: 10; A: 10; T: 40
Deoxyribonucleoside (c) C: 40; A: 10; T: 10
(b) A- Ribonucleotide, B-Deoxyribonucleotide (d) C: 10; A: 40; T: 40
(c) A- Nucleoside, B- Nucleotide
(d) A- Nucleotide, B- Nucleoside Question 6: A short stretch of DNA molecule
has 80 thymine and 80 guanine bases. The
Question 3: Assertion: The sugar phosphate total number of nucleotides in the DNA
backbone of two chains in DNA double fragment is
helix show antiparallel polarity. Options:
Reason: The phosphodiester bonds in one (a) 40
strand go from a 3’ carbon of one (b) 80
nucleotide to a 5’ carbon of adjacent (c) 160
nucleotide, whereas those in (d) 320
complementary strands go vice versa.
Options: Question 7: Given below are two statements:
(a) If both assertion and reason are true and Statement I: The two strands in a DNA
reason is the correct explanation of double helix are complementary in nature.
assertion. Statement II: Covalent bonds are responsible
(b) If both assertion and reason are true but for the stability of DNA double-helical
reason is not the correct explanation of structure.
assertion. Options:
(c) If the assertion is true but the reason is (a) Both Statement I and Statement II are
false. correct
(d) If both assertion and reason are false. (b) Both Statement I and Statement II are
incorrect
Question 4: Which of the following is NOT (c) Statement I is correct but Statement II is
true about Watson and Crick’s DNA incorrect
double helix model?

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(d) Statement I is incorrect but Statement II is (d)Two adjacent sugars in a DNA strand are
correct joined by a phosphodiester bond.

Question 8: If a double stranded DNA has Question 12: Which of the following was
20% of cytosine, what will be the NOT an observation by Watson and Crick?
percentage of adenine in it? Options:
Options: (a)Phosphodiester bonds link with
(a) 20% deoxyribose sugar and form the backbone
(b) 40% of DNA.
(c) 30% (b)The pattern of hydrogen bonding
(d) 60% between bases results in an approximate
uniform distance between two strands.
Question 9: In one polynucleotide strand of a (c)Total number of purines is equal to total
DNA molecule the ratio of A + T/G + C is number of pyrimidines.
0.3. What is the A+ G/T + C ratio of the (d)In the right-handed helix, the distance
entire DNA molecule? between two base pairs is 3.4 nm.
Options:
(a) 0.3 Question 13: Histone proteins are
(b) 0.6 Options:
(c) 1.2 (a)Basic, negatively charged
(d) 1 (b)Basic, positively charged
(c)Acidic, positively charged
Question 10: Assertion: DNA is considered to (d)Acidic, negatively charged
be better genetic material than RNA for
most organisms. Reason: 2’-OH group Question14: What does the given diagram
present in DNA makes it liable and less represent?
reactive.
Options:
(a) If both assertion and reason are true and
reason is the correct explanation of
assertion.
(b) If both assertion and reason are true but
Options:
reason is not the correct explanation of
(a)Nucleosome
assertion.
(b)Spliceosome
(c) If the assertion is true but the reason is
(c)Histone complex
false.
(d)Both (a) and (b)
(d) If both assertion and reason are false.
Question 15: Match column - I with column-
Question 11: Which of the following is
II and select the correct option from the
incorrect for the double helical model
codes given below.
proposed by Watson and Crick?
Options:
(a)The one complete turn of helical strand
(pitch) is 0.34 nm containing roughly 10
base pairs.
(b)The double helical model of the DNA was
proposed by Watson and Crick based on X-
ray didraction data.
(c)In the sugar phosphate backbone, the
bases are projected inwards.

Options:

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 (a)A-ii, B-iii, C-iv, D-i, E-v (c) (i) and (iv)
(b)A-v, B-iv, C-iii, D-i, E-ii (d) (i), (ii) and (iii)
(c)A-ii, B-iii, C-iv, D-ii, E-v
(d)A-i, B-iv, C-iii, D-ii, E-v Question 20: All the following statements are
in accordance with the theory of RNA
Question 16: A bacteriophage grown in world except:
sulfur 35S medium incorporates (i) Essential life processes such as
radioactivity in metabolism evolve around RNA
Options: (ii) RNA acts as catalyst in some of the
(a)Carbohydrate biochemical reactions in the body
(b)Protein (iii)RNA has evolved from DNA through
(c)DNA chemical modifications
(d)RNA Options:
(a) (i) and (ii)
Question 17: Experiment of Hershey-Chase (b) (i) and (iii)
confirmed that: (c) (ii) and (iii)
Options: (d) (i), (ii) and (iii)
(a)DNA is always formed from DNA in
semiconservative manner Question 21: During DNA replication,
(b)Radioactive sulfur on the viral protein discontinuous fragments in lagging strand
enters in bacterial cell progeny are joined with the help of enzyme:
(c)DNA is genetic material, not protein Options:
(d)Radioactive phosphorus was only found (a) Helicase
in supernatant (b) DNA Ligase
(c) Polymerase
Question 18: Which of the following criteria (d) Ribozyme
should be fulfilled by a molecule to act as a
genetic material? Question 22: Select the incorrect statement
(i)It should be able to replicate. regarding DNA replication
(ii)It should be structurally and chemically Options:
stable. (a) Leading strand is formed in the 5'→3'
(iii)It should be able to undergo slow direction.
mutations. (b) Okazaki fragments catalyzed
(iv)It should be able to express itself in the polymerisation in 5'→3' direction
form of ‘Mendelian characters’. (c) DNA polymerase catalyzes polymerisation
Options: in 5'→3' direction
(a)(i) and (ii) (d) DNA polymerase catalyzes polymerisation
(b)(ii) and (iii) in 3'→5' direction
(c)(i), (ii) and (iii)
(d)(i), (ii), (iii) and (iv) Question 23: Read the given statements and
Question 19: Select the correct statements select the correct option. Statement I: The
out of the following: enzyme required for DNA replication is an
(i) Both DNA and RNA are able to mutate edicient enzyme.
(ii) RNA being unstable, mutates at a faster Statement II: This enzyme can polymerise
rate large numbers of nucleotides in a very
(iii)RNA shows catalytic properties short time.
(iv)Presence of uracil at place of thymine (T) Options:
confers additional stability to RNA (a) Both Statement I and Statement II are
Options: correct
(a) (i) and (ii) (b) Both Statement I and Statement II are
(b) (ii) and (iii) incorrect

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(c) Statement I is correct but Statement II is Question 28: During transcription, the site of
incorrect DNA molecule at which RNA polymerase
(d) Statement I is incorrect but Statement II is binds is called
correct Options:
(a) Promoter
Question 24: Which of the following is not a (b) Regulator
part of the transcription unit? (c) Receptor
Options: (d) Enhancer
(a) Inducer
(b) Promoter Question 29: The given figure represents the
(c) Terminator process of transcription in bacteria.
(d) Structural gene

Question 25: Which of the following is true for

template strand?
Options:
(a) It is known as the coding strand. Select the option which correctly labels A,B
(b) RNA polymerase uses this strand for and C.
coding of RNA. Options:
(c) It has a polarity 5'→3’. (a) A-DNA, B-RNA, C-Promoter
(d) It has the sequence same as RNA (except (b) A-RNA, B-RNA polymerase, C-Rho factor
thymine at the place of uracil). (c) A-RNA, B-RNA polymerase, C-Sigma
factor
Question 26: The given diagram represents (d) A-DNA, B-DNA polymerase, C-RNA
the components of the transcription unit.
Select the correct answer regarding it Question 30: Polycistronic messenger RNA
(mRNA) usually occurs in
Options:
(a) Bacteria
(b) Prokaryotes
Options: (c) Eukaryotes
(a) A – Terminator, B – Promoter, C - Template (d) Both (a) and (b)
strand, D - Coding stand
(b) A - Promoter, B - Terminator, C - Coding Question 31: Which of the following
strand, D - Template strand statements is incorrect regarding the
(c) A - Promoter, B - Terminator, C - Template mRNA processing?
strand, D - Coding strand Options:
(d) A - Terminator, B - Promoter, C - Coding (a) Bacterial mRNA does not need any mRNA
strand, D - Template strand processing.
(b) Capping at 5’ end of eukaryotic hnRNA
Question 27: Find out the sequence of mRNA prevents degradation of primary
if the coding strand sequence is transcript.
5’CGTCCTACCGAA 3′ (c) Splicing of primary transcript removes
Options: coding sequences and joins axons in a
(a) 5’GCAGGAUGGCUU 3′ definite order.
(b) 5’CGUCCUACCGAA 3′ (d) hnRNA is a precursor of eukaryotic mRNA.
(c) 3’GCAGGAUGGCUU 5′
(d) 3’CGUCCUACCGAA5′ Question 32: The structural genes in
eukaryotes possess coding and non-
coding sequences called as _(i) and
(ii) respectively.

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Options: (c) A - Methylated Cap, B - Non coding region,
(a) (i) Promoter, (ii) Operator C - Coding region, D - Poly A tail
(b) (i) Introns, (ii) Exons (d) A - Methylated cap, B - Coding region, C -
(c) (i) Exons, (ii) Introns Non -coding region, D - Poly A tail
(d) (i) Enhancer, (ii) Silencer
Question 37: Amino acid acceptor end of
Question 33: In the genetic dictionary, there tRNA lies at
are 64 codons as Options:
Options: (a) 5' end
(a) 64 amino acids are to be coded (b) 3' end
(b) 64 types of tRNAs are present (c) Anticodon loop
(c) There are 44 nonsense codons and 20 (d) D-loop
sense codons
(d) Genetic code is triplet. Question 38: During translation, activated
amino acids get linked to tRNA. This
Question 34: Sickle cell anaemia results from process is commonly called as
a single base substitution in a gene thus it Options:
is an example of (a) Charging of tRNA
Options: (b) Discharging of tRNA
(a) Point mutation (c) Aminoacylation of tRNA
(b) Frameshift mutation (d) Both (a) and (c)
(c) Silent mutation
(d) Both (a) and (b) Question 39: Assertion: tRNA recognizes its
corresponding codon on mRNA. Reason:
Question 35: Match column I with Column II tRNAs are specific for each amino acid.
and select the correct option from the Options:
codes given below. (a) If both assertion and reason are true and
reason is the correct explanation of
assertion.
(b) If both assertion and reason are true but
reason is not the correct explanation of
assertion.
(c) If the assertion is true but the reason is
false.
Options: (d) If both assertion and reason are false.
(a) A-ii, B-i, C-iii
(b) A-i, B-iii, C-ii Question 40: In lactose operon, the repressor
(c) A-iii, B-i, C-ii protein
(d) A-ii, B-iii, C-i Options:
(a) Binds with preferred carbon sources such
Question 36: Match the A, B, C and D with the as glucose.
given diagram of mRNA. (b) Binds with the inducer and transcription of
structural genes turns on.
(c) Binds with the RNA polymerase and
transcription of structural genes turns od.
Options: (d) Inhibits the lactose transport in the cell
(a) A - Methylated cap, B - Initiation codon, C - from the growth medium.
Termination codon, D - Poly A tail
(b) A - Poly A tail, B - Termination codon, C - Question 41: Assertion: Eukaryotic mRNA
Initiation codon, D - Methylated cap requires post transcription processing for
formational mRNA. Reason: Eukaryotic

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 transcripts possess extra non functional
segments called introns.
Options:
(a) If both assertion and reason are true and
reason is the correct explanation of
assertion.
(b) If both assertion and reason are true but
reason is not the correct explanation of Options:
assertion. (a)A – Repressor, B – Inducer, C - Beta
(c) If the assertion is true but the reason is galactosidase, Y – Permease, Z -
false. Transacetylase
(d) If both assertion and reason are false. (b)A - Repressor, B - Inducer, C - Permease,
Y - Beta galactosidase, Z - Transacetylase
Question 42: What does “lac” refer to in what (c)A - Inducer, B - Repressor, C - Beta
we call the lac operon ? galactosidase, Y - Permease, Z -
Options: Transacetylase
(a) Lactose (d)A - Inducer, B - Repressor, C - Beta
(b) Lactase galactosidase, Y - Transacetylase, Z –
(c) Lac insect Transacetylase
(d) The number 1,00,000

Question 43: E. coli cells with a mutated z

gene of the lac operon cannot grow in
medium containing only lactose as the
source of energy because
Options:
(a) The lac operon is constitutively active in
these cells.
(b)They cannot synthesize functional beta
galactosidase.
(c)In the presence of glucose, E. coli cells
do not utilize lactose.
(d)They cannot transport lactose from the
medium into the cell.

Question 44: In E. coli, during lactose

metabolism repressor binds to
Options:
(a)Regulator gene
(b)Operator gene
(c)Structural gene
(d)Promoter gene.

Question 45: The given figure shows lac

operon and its function. Select the correct
option which correctly labels A, B, X, Y and
Z.

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