MCQ Questions for Class 12 Medical Biology Molecular Basis Of Inheritance Quiz 3

The transcription unit extends from

0%
TATA box to start point
0%
TATA box to stop codon
0%
Start point to stop codon
0%
35 sequence to start point

Which of the following amino acid has hydroxyl methyl group as its R group?

0%
Serine
0%
Proline
0%
Alanine
0%
Arginine

Two or more codons encoding the same amino acid is due to

0%
Non-ambiguous
0%
Degeneracy of codon
0%
Non-overlapping of codon
0%
Non-sense codon

How many nitrogenous bases are there in a codon?

0%
3
0%
2
0%
1
0%
5

What is the main aim of the human genome project?

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To introduce new genes into humans
0%
To identify and sequence all the genes present in human DNA
0%
To develop better techniques for comparing two different human DNA samples
0%
To remove disease causing genes from human DNA

What is the process of joining together different DNA fragments often referred as?

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Transcription
0%
Cloning
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Gene splicing
0%
DNA amplification

What is meant by DNA fingerprinting ?

0%
Techniques used for molecular analysis of different specimens of RNA
0%
Techniques used for identification of fingerprints of individuals
0%
Molecular analysis of profiles of DNA samples
0%
Analysis of DNA samples using imprinting devices

What is the total number of nitrogenous bases in human genome estimated?

0%
3.5 million
0%
35 thousand
0%
35 million
0%
3.1 billion

Human genome project was initiated by

0%
Francis Collins and Roderick
0%
Watson and Crick
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Beadle and Tatum
0%
Paul Berg and Wollman

Centre of DNA Fingerprinting and Diagnostics (CDFD) is located at?

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Delhi
0%
Chennai
0%
Kolkata
0%
Hyderabad

Which of the character is not applicable to tRNA?

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It is the smallest of the RNAs
0%
It acts as an adapter for amino acids
0%
It has a clover leaf like structure
0%
It is the largest of the RNAs

Which enzyme plays important role in transcription?

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DNA dependent RNA polymerase
0%
DNA dependent DNA polymerase
0%
RNA dependent DNA polymerase
0%
RNA dependent RNA polyrnerase

What is the basis of DNA fingerprinting ?

0%
The double helix
0%
Errors in base sequence
0%
Polymorphism in sequence
0%
DNA replication
0%
DNA coiling

Gel electyrophoresis is used for

0%
Construction of recombinant DNA by joining with cloning vectors
0%
Isolation of DNA molecule
0%
Cutting of DNA into fragments
0%
Separation of DNA fragments according to their size

The two polynucleotide chain in DNA are:-

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Semiconservative
0%
Parallel
0%
Discontinuous
0%
Antiparallel

Assertion: DNA polymerase-I acts as proofreader.

Reason: DNA polymerase-I removes mismatched nucleotides.

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If both the assertion and the reason are true and the reason is a correct explanation of the assertion
0%
If both the assertion and reason are true but the reason is not a correct explanation of the assertion
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If the assertion is true but the reason is false
0%
If both the assertion and reason are false
0%
If the assertion is false but reason is true

Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as 'start' or 'stop' codon : -

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UCG Start
0%
UUU Stop
0%
UGU Leucine
0%
UAC Tyrosine

Which one of the following pairs of terms/names mean one and the same thing?

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Gene pool - Genome
0%
Codon - Gene
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Cistron - Triplet
0%
DNA fingerprinting - DNA profiling

Production of a human protein in bacteria by genetic engineering is possible because

0%
Bacterial cell can carry out the RNA splicing reactions
0%
The mechanism of gene regulation is identical in humans and bacteria
0%
The human chromosome can replicate in bacterial cell
0%
The genetic code is universal

Assertion: The tRNA molecules possess anticodons.

Reason: It needs the message in form of codon.

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If both the assertion and the reason are true and the reason is a correct explanation of the assertion
0%
If both the assertion and reason are true but the reason is not a correct explanation of the assertion
0%
If the assertion is true but the reason is false
0%
If both the assertion and reason are false
0%
If the assertion is false but reason is true

Variable number of tandem repeats (VNTRs) in the DNA molecule are highly useful in which of the following?

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Recombinant DNA technology
0%
DNA fingerprinting
0%
Monoclonal antibody production
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Stemcell culture

Semiconservative replication of DNA was first demonstrated in

0%
Salmonella typhimurium
0%
Drosophila melanogaster
0%
Escherichia coli
0%
Streptococcus pneumoniae

Explanation

Answer: (C)

$\textit Escherichia coli$ .

Explanation:

DNA replication is semiconservative in nature.
During the replication process, one strand is a newly synthesized strand while the parental strand remains intact, this property of DNA replication is known as the semiconservative nature of DNA replication.
Methew Messelson & Franklin Stahl (1958) experimentally proved the semiconservative replication of DNA.
They did an experiment on $\textit Escherichia coli$ .

Hence, the semi-conservative nature of DNA replication was first demonstrated on

$\textit Escherichia coli$ .

Assertion: DNA fingerprinting involves identifying differences in some specific regions in DNA sequence.

Reason: In repetitive DNA sequences, a small stretch of DNA is repeated many times.

0%
If both the assertion and the reason are true and the reason

is a correct explanation of the assertion
0%
If both the assertion and reason are true but the reason is

not a correct explanation of the assertion
0%
If the assertion is true but the reason is false
0%
If both the assertion and reason are false
0%
If the assertion is false but reason is true

The following ratio is generally constant for a given species :-

0%
T + C / G + A
0%
G + C / A+ T
0%
A + C / T + G
0%
A + G / C +T

A codon in mRNA has

0%
3 bases
0%
2 bases
0%
1 base
0%
Number of bases vary

Khorana and his colleague synthesized an RNA molecule with repeating sequences of U and G bases. The RNA with, UGUGUGUGUGUG produced a tetra-peptide with alternating sequences of cysteine and valine. This proves that codon for cysteine and valine is

0%
UGG, GUU
0%
UUG, GGU
0%
UGU, GUG
0%
GUG, UGU

The process of mRNA synthesis on a DNA is known as

0%
Translation
0%
Transcription
0%
Transduction
0%
Transformation

Genetic information in a DNA molecule is coded in the

0%
sequence of nucleotides
0%
base pairing
0%
turning pattern of the helix
0%
portion of each base present

If genetic code is tetraplet then what is the possible number of codons which code 20 types of amino acids?

0%
261
0%
64
0%
256
0%
43

In the double helix model of DNA as proposed by J. D. Watson and F.S.C. Crick, each base pair is how far from the next base pair:

0%
0.034nm
0%
0.34nm
0%
3.4nm
0%
34nm

Double helix model of DNA which was proposed by Watson and Crick was of

0%
C-DNA
0%
B-DNA
0%
D-DNA
0%
Z-DNA

B-DNA double helix makes a complete turn with

0%
Every 10 base pairs
0%
Every 20 base pairs
0%
Every 36 base pairs
0%
Every 3-6 base pairs

Explanation

Watson and Crick proposed two strands of DNA - each in a right hand helix wound around the same axis. The two strands are held together by H-bonding between the bases. The diameter of B-DNA is 20

$\mathring A$ and there are about 10 bases per helical turn (36

$^o$ of twist along the helix for each base pair). The major groove is wide, while the minor groove is narrow. Owing to the location of the helical axis in the centre of the base pairs, the edges of the base pairs are about equally deep in the interior.

Which of the following is not directly formed from DNA?

0%
DNA
0%
Protein
0%
m RNA
0%
t RNA

What does bacterial genome contain?

0%
Double stranded circular DNA
0%
Double stranded linear DNA
0%
Single stranded circular DNA
0%
Single stranded DNA

Degeneracy of genetic code was discovered by

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McClintock
0%
Khorana
0%
Ochoa
0%
Baurnfield & Nirenberg

Genetic code was discovered by

0%
Nirenberg & Matthaei
0%
Kornberg & Crick
0%
Khorana & Kornberg
0%
Gamow

DNA polymerase is needed for

0%
Replication of DNA
0%
Synthesis of DNA
0%
Elongation of DNA
0%
All of the above

DNA directed synthesis of mRNA is called as

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Transcription
0%
Translocation
0%
Transduction
0%
Replication

During transcription, if the nucleotide sequence of the DNA strand that is being coded is ATACG, then the nucleotide sequence in the mRNA would be

0%
TATGC
0%
TCTGG
0%
UAUGC
0%
UATGC

In bacteria, the codon AUG stands for

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Glycine
0%
Methionine
0%
N-formyl methionine
0%
Both B and C

During transcription, the DNA site at which RNA polymerase binds is called as

0%
Promoter
0%
Regulator
0%
Receptor
0%
Enhancer

Explanation

$\textbf{Correct option: (A)}$

$\textbf{Solution:}$

$\textbf{Option (A):}$

$\bullet$ Transcription is the process of RNA formation from DNA.

$\bullet$ During transcription, RNA polymerase makes a copy of a gene from the DNA to mRNA.

$\bullet$ During transcription, the DNA site at which RNA polymerase binds is called a promoter.

$\bullet$ Transcription begins with binding of sigma factor proteins to the RNA polymerase holoenzyme, thus, allowing it to bind to promoter DNA.

$\bullet$ RNA polymerase creates a transcription bubble, which separates the two strands of the DNA helix.

$\bullet$ Then RNA polymerase moves towards the transcription start site for the process of transcription.

$\textbf{Option (B):}$

$\bullet$ Regulatory sequences are bound tightly and specifically by transcriptional regulators, proteins that can recognize DNA sequences and bind to them.

$\bullet$ The binding of regulatory proteins to the DNA can regulate transcription by preventing or increasing transcription from a particular promoter.

$\textbf{Option (C):}$

$\bullet$ Enhancer sequences are regulatory DNA sequences that bind by specific proteins called transcription factors, enhance the transcription of an associated gene.

$\bullet$ Enhancer sequences can be positioned in both forward or reversed sequence orientations and still affect gene transcription.

Hence, the correct option is (A)

In a mRNA sequence of N

$_2$ -base is 5' AUG GUG CUC AAA 3'. What is the correct sequence of anticodons which recognizes codons of mRNA

0%
a, b, c, d
0%
d, a, b, c
0%
c, d, b, a
0%
d, c, b, a

Explanation

The primary nucleobases are cytosine (DNA and RNA), guanine (DNA and RNA), adenine (DNA and RNA), thymine (DNA) and uracil (RNA), abbreviated as C, G, A, T and U respectively. Because A, G, C, and T appear in the DNA, these molecules are called DNA-bases. A, G, C and U are called as RNA-bases. Uracil and thymine are identical except that uracil lacks the 5' methyl group. Adenine and guanine belong to the double-ringed class of molecules called purines. Cytosine, thymine, and uracil are all pyrimidines. In normal spiral DNA the bases form pairs between the two strands. A with T and C with G. Purines pair with pyrimidines mainly for dimensional reasons. only this combination fits the constant width geometry of the DNA spiral. The A-T and C-G pairings are required to match the hydrogen bonds between the amine and carbonyl groups on the complementary bases. So, if a mRNA sequence of N

$_2$ base is 5' AUG GUG CUC AAA 3', the correct sequence of anticodons are UAC, CAC, GAG and UUU. Thus, option C is correct and other options are wrong.

Sometimes the starting codon is GUG in place of AUG, GUG normally stands for

0%
Valine
0%
Glycine
0%
Methionine
0%
Tyrosine

Transcription means synthesis of

0%
DNA
0%
Protein
0%
mRNA
0%
Enzyme

Degeneration of a genetic code is attributed to the

0%
First member of a codon
0%
Second member of a codon
0%
Entire codon
0%
Third member of a codon

One turn of the helix in a B form DNA is approximately

0%
20 nm
0%
0.34 nm
0%
3.4 nm
0%
2 nm

Explanation

Majority of DNA present in the cytoplasm of living cells exist in double helical structure as described by Watson and Crick. Watson and Crick proposed that DNA molecule is in the form of a double helix with two polynucleotide chains coiled around one another in a spiral. This is known as B-DNA or biological DNA.

It has 10 nucleotides pairs per turn of the double helix and is right handed with a diameter of 20

$\mathring A$ . One complete turn of the double helix is 34

$\mathring A$ .The distance between adjacent stacks or nucleotides is 3.4

$\mathring A$ .

Each chain has a sequence of oligonucleotides attached together by phosphodiester bonds joining the adjacent deoxyribose molecules. The two polynucleotide chains are helically coiled round one another with the help of hydrogen bonds between nitrogen bases of opposite strands. The base pairing is specific: adenine always pairs with thymine and cytosine always pairs with guanine. Other forms of DNA are A-DNA found in high salt concentration or in dehydrated form with 11 nucleotide pairs per turn and is right handed, its diameter is 23 Z-DNA is left handed with 12 nucleotide pairs per turn. The length of DNA double helix in a typical mammalian cell is calculated comes out to be approximately 2.2metres (by multiplying the total number of bp with distance between two consecutive bp, i.e., 6.6million bp X 0.34 nanometer/bp.

Which of the following is an initiation codon?

0%
AUG
0%
UAG
0%
UGA
0%
UAA

Genetic code is

0%
Universal
0%
Non-ambiguous
0%
Triplet
0%
All of the above

A sample of DNA is found to have the base composition (mole ratio) of A = 40, T = 22, G = 21 and C =This suggests

0%
DNA is circular duplex.
0%
DNA is linear duplex.
0%
DNA is single stranded.
0%
DNA has high melting point.

$Drosophila$ , a set of homeotic genes which control body plan at the time of organ differentiation is known as

0%
TATA box
0%
Homeobox
0%
Pribnow box
0%
All of the above

Explanation

Homeodomain is a DNA-binding domain having 60 amino acids that is present in transcription factors which regulate expression of homeotic genes, hence, the name homeodomain. These genes regulate the development of body patterns and known as homeogenes. The DNA sequence that encodes this domain is known as the homeobox.

The Pribnow box is the consensus sequence of six nucleotides "TATAAT" and forms the essential part of a promoter site on bacterial DNA. This site is recognized and bound by RNA polymerase subunit during transcription initiation. Since,

$Drosophila$ is an eukaryotic organism, it can not have pribnow box which is prokaryotic promoter site.
The TATA box is a DNA sequence in promoter region of archaeal and eukaryotic housekeeping genes. These genes are the constitutive genes that maintain the basic cellular function and are expressed under normal physiological conditions. Hence, TATA box does not regulate the homeotic genes. Thus, correct answer is option B.

CBSE Questions for Class 12 Medical Biology Molecular Basis Of Inheritance Quiz 3 - MCQExams.com

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Practice Class 12 Medical Biology Quiz Questions and Answers

CBSE Questions for Class 12 Medical Biology Molecular Basis Of Inheritance Quiz 3 - MCQExams.com

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Practice Class 12 Medical Biology Quiz Questions and Answers

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