CBSE Questions for Class 12 Medical Biology Molecular Basis Of Inheritance Quiz 6 - MCQExams.com

Duplication of DNA is called as
  • Replication
  • Transduction
  • Transcription
  • None of the above
DNA polymerase enzyme is required for the synthesis of 
  • RNA from DNA
  • DNA from DNA
  • RNA from RNA
  • DNA from RNA
Identify the triplet codons which code for amino acids serine and proline.  
(a) UCC (b) CCA (c) GGG (d) AAG. 
The correct answer is
  • a and c
  • b and d
  • c and d
  • a and b
Anitcodon is present on
  • rRNA
  • mtRNA
  • tRNA
  • mRNA
Which one of the following pairs of codons is correctly matched with their function or the signal for the the particular amino acid?
  • AUG, ACG - Start/methionine
  • UUA, UCA - Leucine
  • GUU - Alanine
  • UAG, UGA - Stop
The basis of DNA fingerprinting is
  • The double helix
  • Error in base sequence
  • Polymorphism in sequence
  • DNA replication
  • DNA coiling
DNA strands are anti-parallel because of
  • H-bonds
  • Phosphate diester bonds
  • Disulphide bonds
  • Peptide bonds
What is the DNA strand on which a new DNA is synthesised?
  • Complementary
  • Primer
  • Template
  • Okazaki fragment
There are 64 codons in genetic code dictionary, because
  • There are 64 types of tRNA's found in the cell.
  • There are 44 meaningless and 20 codons for amino acids.
  • Genetic code is triplet.
  • There are 64 amino acids to be coded.
Which of following has a clover leaf shaped structure?
  • tRNA
  • rRNA
  • DNA
  • mRNA
Anticodon is associated with
  • mRNA
  • DNA
  • tRNA
  • rRNA
It is theoretically possible for a gene from any organism to function in any other organism. Why is this possible ?
  • All organisms have ribosomes.
  • All organisms have the same genetic code.
  • All organisms are made up of cells.
  • All organisms have similar nuclei.
The term degeneracy was given by
  • A. Kornberg
  • Barbara McClintock
  • Bernfield and Nirenberg
  • Hershey and Chase
Human Genome Project (HGP) is closely associated with the rapid development of a new area in biology called as
  • Biotechnology
  • Bioinformatics
  • Biogeography
  • Bioscience
Nobel Prize to A.Kornberg and S.Ochoawas given for
  • Artificial synthesis of DNA and RNA
  • Theory of natural selection
  • Mutation theory
  • One gene one polypeptide chain theory
Choose the mismatched pair
  • Nuclein - Friedrich Meischer
  • Double helix of DNA - Watson and Crick
  • Genetic code - Anand Mohan Chakrabarty
  • Gene - Johansen
Genetic code was discovered by
  • Holley and Nirenberg
  • Nirenberg and Matthei
  • Holley Nirenberg and Khorana
  • W. Fleming and Matthei
Termination codon is
  • UAA
  • UCG
  • AUG
  • UUU
Which of the following can result in inaccurate test results in DNA fingerprinting?
  • Sample size
  • Tissue decay
  • Blood transfussion
  • All of the above
Purines possess nitrogen at
  • $$1, 2, 4$$ and $$6$$ position
  • $$1, 3, 5$$ and $$7$$ position
  • $$1, 3, 7$$ and $$9$$ position
  • $$1, 2, 6$$ and $$8$$ position
In a DNA molecule distance between two bases is
  • $$2nm/20\overset{o}{A}$$
  • $$0.2nm/2\overset{o}{A}$$
  • $$3.4nm/34\overset{o}{A}$$
  • $$0.34nm/3.4\overset{o}{A}$$
Nitrogenous base present in DNA are
(a) Thymine
(b) Cytosine
(c) Adenine
(d) Guanine
  • a, b, c
  • a, c, d
  • b, c, d
  • all
Which of the following tests helps to solve crimes?
  • Proteomics
  • DNA fingerprinting
  • Blood analysis
  • None of the above
.................... is a forensic technique used to identify individuals by characteristics of their DNA.
  • DNA profiling
  • DNA fingerprinting
  • DNA typing
  • All of the above
Double helical model of DNA was proposed by
  • Watson and Crick
  • Kornberg and Ochoa
  • Jacob and Monod
  • Beadle and Tatum
If the tRNA anticodon for the amino acid is CAA (reading 3' to 5') then the codon for valine (reading 5' to 3') in mRNA will be
  • TTG
  • GGU
  • CCA
  • CCG
  • GUU
Which of the following is characterized by the tightly coiled, condensed form of DNA that is not transcribed?
  • Promoter
  • Enhancer
  • Operator
  • Euchromatin
  • Heterochromatin
The DNA sequences that codes for the polypeptide glutamine, lysine, histidine is
491566_421138b20c1c4c9c85c8c48a0033225d.png
  • CAG AAA CAU
  • ACT CCC ACG
  • GUC UUU GUA
  • GTC TTT GTA
  • None of the above
Degeneracy in genetic code exists because
  • More than one codon can code for a single amino acid
  • One codon can code for multiple amino acids
  • More than on anticodon can bind to a given codon
  • Only one anticodon can bind to a given codon
  • None of the above
Which of the following DNA sequence codes for the tRNA anticodon GAU?
  • GUA
  • GAT
  • CTA
  • CAU
  • UAC
Minisatellites or VNTRs are used in
  • DNA fingerprinting
  • Polymerase chain reaction (PCR)
  • gene therapy
  • gene mapping
Which one of the following codes for an amino acid?
  • Cistron
  • Exon
  • Codon
  • Intron
For the given diagram showing the replication of DNA, asterisk (*) represents
490943_8c9fac495389476c932762e8739fc3f9.png
  • Promoter
  • Okasaki fragment
  • Template
  • Lagging strand
  • Leading strand
Which of the following is utilized by all living organisms?
  • $$C{O}_{2}$$
  • A triplet genetic code to produce proteins
  • Oxygen
  • ADP as cellular energy
  • Membrane-bound organelles

The helicase enzyme breaks

I. Covalent bonds

II. Hydrogen bonds

III. Ionic bonds
  • II only
  • I and II
  • I and III
  • II and III
  • I, II and III
Choose the correct mRNA sequence for the given DNA sequence.
5'- AGTTCG- 3'
  • 3'-TCUUGC-5'
  • 5'-UCAACG-3'
  • 5'-AGTTCG-3'
  • 5'-TCAACG-3'
  • 3'-UCAAGC-5'
Which of the following statements, best supports the claim that organisms share fundamental processes as a result of evolution?
  • All organisms have the ability to use oxygen to capture energy from the breakdown of organic molecules.
  • All organisms introduced into new environments have the capacity to fill vacant ecological roles.
  • All organisms have structures such as chloroplasts and mitochondria within their cells that reflect past symbiotic relationships between prokaryotic precursors.
  • All organisms share a genetic code organized into triplet codons, making it possible for one organism to express a gene from any other organism.
The given table shows the genetic code depicting the amino acids that correspond to mRNA codons. Each codon is read from $${3}^{\prime}$$ (first nucleotide) to $${5}^{\prime}$$ (third nucleotide). Find out the amino acid sequence that can be assembled from the mRNA associated with the given DNA strand.
DNA template strand: $${5}^{\prime} - GCG ACA TAC ACT - {3}^{\prime}$$

497169_3cc35acf59cf430fb37f8635287b5ea8.png
  • Ala - Cys - Met
  • Arg - Cys - Met
  • Ala - Thr - Tyr - Thr
  • Ala - Thr - Tyr - Trp
  • Arg - Thr - Tyr - Thr
Replication of a complementary strand of DNA using an existing template strand of DNA can only be accomplished in the presence of RNA nucleotides to serve as primers for replicative enzymes. This fact is drawn upon as evidence in support of
  • The snowball Earth hypothesis.
  • The abiotic synthesis of organic monomer molecules, also known as the "Reducing Atmosphere" hypothesis.
  • The endosymbiotic theory for the evolution of eukaryotic life.
  • The existence of a genetic system that predates the use of DNA as genetic material.
If a molecule was introduced that interfered with the normal function of the enzyme DNA ligase, what would be the most likely effect during replication?
  • DNA could not unwind for replication to proceed.
  • Fragments of DNA could not be joined together.
  • New DNA nucleotides could not be added to the growing strand.
  • RNA primers could not be replaced with DNA nucleotides.
Rosalind Franklin produced an X-ray image that helped Watson and Crick determine the width of a DNA molecule.

What did this information help them realize?
  • Bonding between two purines would be consistent with the diameter of the DNA helix.
  • Chargaffs Rule did not apply to the DNA molecule.
  • Bonding between a purine and pyrimidine would be consistent with this width of a DNA helix since each rung has a three-ring molecular dimension.
  • Adenine must bond with cytosine, and guanine must bond with thymine on each rung of the DNA ladder to accommodate for proper diameter of the double helix.
Which of the following is a transcription factor produced by a regulatory gene?
  • A promoter
  • An operon
  • A cofactor
  • A repressor
Which choice describes the incorrect statement regarding the bonding arrangement in the Watson-Crick model of DNA?
  • Deoxyribose can bind to the nitrogenous bases A, T, C or U.
  • A phosphate group binds to each rung of the ladder containing a purine and a pyrimidine.
  • Hydrogen bonds connect the nucleotide from one strand to the nucloetide of the other strand.
  • Phosphodiester bonds link to deoxyribose forming the backbone of DNA.
A strand of DNA has the following sequence:  5'-ACTGCCTATGCT-3'.
 What is the complementary strand that will be formed when the molecule undergoes replication during the M phase of the cell cycle?
  • 5'-TGACGGATACGA- 3'
  • 3' -TGACGGATACGA- 5'
  • 5'-ACTGCCTATGCT-3'
  • 3'-ACTGCCTATGCT- 5'
  • 3'-UGACGGAUACGA-5'
All of the following statements about DNA replication are true except 
  • DNA replication begins with an RNA primer.
  • Hydrogen bonds must be broken for replication to occur.
  • DNA replication begins at the promoter.
  • Bacterial DNA replication proceeds in a circular fashion.
  • One half of a new DNA strand must be assembled as small pieces instead of a continuous piece.
A mutation occurs in the gene encoding the enzyme DNA polymerase of a eukaryotic cell. Which of the following events of DNA replication would not occur? 
  • The DNA helix would not unwind properly for replication.
  • The DNA helix would not be held apart so that it could be replicated by DNA polymerase.
  • An RNA primer would not be generated so that DNA replication could begin.
  • Complementary nucleotides would not be paired with the template strands.
  • The Okazaki fragments on the lagging strand of DNA would not be joined together correctly.
A single strand sequence of coding DNA reads 5' GCC ATG ACT 3.
What amino acids would be coded with the enzyme RNA polymerase by this section?
Use the codon table to help you.
529866_14172b1da54a48a1bdf5e43016c0438c.png
  • Serine-histidine-glycine.
  • Arginine-tyrosine-stop.
  • Alanine-methionine-threonine.
  • Serine-valine-proline.
Which major concept of genetics was illustrated in the model designed by Watson and Crick?
529336_bb246307fdfe4e6d8a0430f54bb009f2.png
  • DNA exhibits a double helix structure.
  • DNA was the molecule of heredity.
  • DNA copies itself through semiconservative replication.
  • Amino acids may have been the first biological molecules formed on Earth.
The genetic code of a segment of DNA reads $$3$$ TTCGGGTAGAAA $$5$$. A mutation occurs between the second and third base where an extra cytosine is added.
What would be the resulting amino acids that would be translated from the gene?
529872_44bc5fd09f98405595e926b54d3cf83a.png
  • Lysine-Histidine-Arginine-Phenylalanine
  • Lysine-Alanine-Histidine-Leucine
  • Lysine- Arginine-Asparagine-Glutamic acid
  • Lysine-Alanine-Phenylalanine-Glutamic acid
Which best describes the process of DNA replication?
  • Multiple "bubbles" form in the DNA that proceed with replication in both directions from the bubble.
  • A single "bubble" forms in the DNA that proceeds with replication in a single direction from the bubble.
  • DNA polymerase adds nucleotides to each separated strand of the DNA molecule at the replication fork replicating two leading strands at one end of the bubble and two lagging stands at the other side of the bubble.
  • Replication occurs at a single replication fork that replicates lagging and leading strands in the same direction.
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