CBSE Questions for Class 12 Medical Biology Molecular Basis Of Inheritance Quiz 1 - MCQExams.com

A human gene product can be produced by genetically engineered bacteria. This is possible, because the
  • Genetic code is universal.
  • Human chromosome can replicate in bacterial cell.
  • Bacterial cell can carry out the splicing reaction.
  • Mechanism of gene regulation is identical in humans and bacteria.
Genetic code determines
  • Structural pattern of an organism.
  • Sequence of amino acid in protein chain.
  • Variation in offsprings.
  • Consistency of morphological trait.
64 Codons constitute genetic code because
  • There was 64 types of amino acid.
  • 64 types of tRNA.
  • Genetic code is triplet.
  • There are 64 enzymes.
Length of one loop of B DNA is
  • 3.4 nm
  • 0.34 nm
  • 20 nm
  • 10 nm
How many nucleotides in messenger RNA's sequence makes a codon for an amino acid?
  • Three
  • Four
  • One
  • Two
What would happen if in a gene encoding a polypeptide of 50 amino acids, 25$$^{th}$$ codon (UAU) is mutated to UAA?
  • A polypeptide of 24 amino acids will be formed.
  • Two polypeptides of 24 and 25 amino acids will be formed.
  • A polypeptide of 49 amino acids will be formed.
  • A polypeptide of 25 amino acids will be formed.
 Nirenberg synthesized an mRNA containing 34 poly-Adenine (A-A-A-A-A-A-----) and found a polypeptide formed of 11 poly-lysine this proved that genetic code for lysine was
  • One-adenine
  • A-A doublet
  • A-A-A triplet
  • Many adenines
Genetic code consists of
  • Adenine & guanine
  • Guanine & cytosine
  • Cytosine & uracil
  • All of the above
In the base sequence, one strand of DNA is GAT, TAG ,CAT, GAC. what shall be the sequence of its complementary strand?
  • CAT, CTG, ATC, GTA
  • GTA, ATC, CTG, GTA
  • ATC, GTA, CTG, GTA
  • CTA, ATC, GTA, CTG
Watson & Crick proposed the model of DNA structures in which of the following years?
  • 1953
  • 1943
  • 1955
  • 1963
Which of the following is an initiation codon?
  • UAG
  • AUC
  • AUG
  • CCU
The one aspect which is not a salient feature of genetic code, is its being
  • Universal
  • Specific
  • Degenerate
  • Ambiguous
Antiparallel strands of a DNA molecule means that
  • One strand turns anti-clockwise.
  • The phosphate groups of two DNA strands, at their ends, share the same position.
  • The phosphate groups at the start of two DNA strands are in opposite position (pole).
  • One strand turns clockwise.
What is antisense technology?
  • When a piece of RNA that is complementary in sequence is used to stop expression of a specific gene.
  • RNA polymerase producing DNA.
  • A cell displaying a foreign antigen used for synthesis of antigens.
  • Production of somaclonal variants in tissue cultures.
Which one of the following pairs of codons is correctly matched with their function or the signal for the particular amino acid?
  • AUG, ACG - Start/Methionine
  • UUA, UCA -  Leucine
  • GUU, GCU - Alanine
  • UAG, UGA - Stop
Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a "triplet"?
  • Beadle and Tatum
  • Nirenberg and Matthaei
  • Hershey and Chase
  • Morgan and Sturtevant
Production of a human protein in bacteria by genetic engineering is possible because
  • Bacterial cell can carry out the RNA splicing reactions.
  • The mechanism of gene regulation is identical in humans and bacteria.
  • The human chromosome can replicate in bacterial cell.
  • The genetic code is universal.
Which one of the following is wrongly matched?
  • Transcription - Writing information from DNA to t-RNA
  • Translation - Using information in mRNA to make protein
  • Repressor protein - Binds to a operator to stop enzyme synthesis
  • Operon - Structural genes, Operator and Promoter
During transcription, holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. What is that sequence called?
  • CAAT box
  • GGTT box
  • AAAT box
  • TATA box
What is not true for genetic code?
  • It is unambiguous.
  • A codon in mRNA is read in a non-contiguous fashion.
  • It is nearly universal.
  • It is degenerate.
DNA fingerprinting refers to
  • Techniques used for identification of fingerprints of individuals
  • Molecular analysis of profiles of DNA samples
  • Analysis of DNA samples using imprinting devices
  • Techniques used for molecular analysis of different specimens of RNA
If the distance between two consecutive base pairs is $$0.34 nm$$ and the total number of base pairs of a DNA double helix in a typical mammalian cell is $$6.6 \times 10^9 bp$$, then the length of the DNA is approximately
  • 2.5 meters
  • 2.2 meters
  • 2.7 meters
  • 2.0 meters
During DNA replication, Okazaki fragments are used to elongate.
  • The lagging strand away from the replication fork
  • The leading strand towards replication fork
  • The lagging strand towards replication fork
  • The leading strand away from replication fork
If the total amount of adenine and thymine in a double-stranded DNA is 45%, the amount of guanine in this DNA will be
  • 22.5%
  • 27.5%
  • 45%
  • 55%
Which one of the following pairs is correctly matched with regard to the codon and the amino acid coded by it?
  • UUU - Valine
  • AAA - Lysine
  • AUG - Cysteine
  • CCC - Alanine
Which codon gives signal for the start of polypeptide (protein) chain synthesis?
  • AUG
  • UGA
  • GUA
  • UAG
What is the function of a non-sense codon?
  • To release polypeptide chain from tRNA.
  • To form an unspecified amino acid.
  • To terminate the message of a gene controlled protein synthesis.
  • To convert a sense DNA into non sense DNA.
Which one of the following pairs is correctly matched with regard to the codon and the amino acid coded by it?
  • UUA - Valine
  • AAA - Lysine
  • AUG - Cysteine
  • CCC - Alanine
Termination of chain growth in protein synthesis is brought about by
  • UUG, UGC, UCA
  • UCG, GCG, ACC
  • UAA, UAG, UGA
  • UUG, UAG, UCG
Which of the following is correct regarding genetic code?
  • UUU is the initiation codon which also codes for phenylalanie.
  • There are $$64$$ triplet codons and only $$20$$ amino acids.
  • Three random nitrogen bases specify the placement of one amino acid.
  • UAA is the nonsense codon which also codes for methionine.
Which one of the following codons codes for the same information as UGC?
  • UGU
  • UGA
  • UAG
  • UGG
During protein synthesis in an organism, at one point the process comes to a halt. Select the group of the three codons from the following from which any one of the three could bring about this halt?
  • UUU, UCC, UAU
  • UUC, UAC
  • UAG, UGA, UAA
  • UUG, UCA, UCG
Which scientist gave wobble hypothesis?
  • R. W. Holley
  • H. G. Khorana
  • M. Nirenberg
  • F. H. C. Crick
AUG codes for
  • Valine
  • Histidine
  • Phenylalanine
  • Methionine
If the total amount of adenine and thymine in a double-stranded DNA is 60% the amount of guainine in this DNA will be
  • 15%
  • 20%
  • 30%
  • 40%
Select the correct option regarding genetic code of Glycine.
  • GUU, GUC, GUA
  • GAU, GAC, GAA
  • GGU, GGA, GGC
  • GGU, GGA, GCU
A segment of DNA contains 1200 nucleotides, of which 200 have adenine base. How many cytosine bases are present in this segment of DNA?
  • 100
  • 200
  • 400
  • 800
Sample can be collected for DNA fingerprinting by
  • Buccal swab
  • Blood
  • Hair
  • All of the above
Guanine pairs with
  • Adenine
  • Cytosine
  • Thymine
  • None of the above
Watson and Crick are known for their discovery that DNA
  • Is a single stranded helix
  • Contains deoxyribose only
  • Is a double stranded helix
  • Synthesizes rRNA
Number of nitrogenous bases in a codon is
  • 3
  • 2
  • 1
  • 5
DNA finger printing was discovered by 
  • Alec Jeffreys
  • Kary Mullis
  • C. Milstein
  • Dr. Paul Berg
A DNA molecule that recognizes specific transcription factors that can stimulate transcription of nearby genes is depicted by
  • Promoter
  • Enhancer
  • Operator
  • Euchromatin
  • Heterochromatin
The process of RNA formation from DNA is called as
  • Transition
  • Translation
  • Transversion
  • Transcription
An amino acid is coded by .............. nucleotides.
  • 1
  • 3
  • 6
  • 9
  • 12
Which of the following enzyme is essential for DNA replication? 
  • DNA polymerase
  • Urease
  • Ligase
  • Zymase
The structure of DNA is
  • Linear
  • Double helix
  • Single helix
  • Triple helix
The above-given model of t-RNA was explained by
606336_a951fd907ea94f1d8eb9657196c60d50.png
  • Watson and crick
  • Friedrick meischer
  • Clover leaf
  • None of the above
The amino acid attaches to the .......... end of the amino acid acceptor arm.
  • 5'
  • 3'
  • Bidirectional
  • None of the above
With four bases the number of possible triplet codons is
  • 24
  • 32
  • 48
  • 64
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