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MCQs BIOCHEMISTRY: DNA Structure

Discussion in 'Exam Preparation' started by aayisha quddus, Dec 4, 2014.

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  1. aayisha quddus

    aayisha quddus Member

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    14
    1.
    The accepted hypothesis for DNA replication is

    A. conservative theory
    B. dispersive theory
    C. semi-conservative theory
    D. evolutionary theory
    Answer & Explanation
    Answer: Option C

    2.
    When DNA polymerase is in contact with guanine in the parental strand, what does it add to the growing daughter strand?

    A. Phosphate B. Cytosine
    C. Uracil D. Guanine
    Answer & Explanation
    Answer: Option B

    3.
    Telomeres are usually rich in which nucleotide?

    A. Adenine B. Guanine
    C. Thymine D. Cytosine
    Answer & Explanation
    Answer: Option B

    4.
    Which is the largest among the followings?

    A. Nucleotide
    B. Nitrogenous base
    C. Phosphate
    D. Carbon
    Answer & Explanation
    Answer: Option A

    5.
    The chromosomal DNA complexes with

    A. three types of histone as H1, H2A and H4
    B. five types of histone as H1, H2A, H2B, H3 and H4
    C. four types of histone as H1, H2A, H3 and H4
    D. two types of histone as H1 and H4
    Answer & Explanation
    Answer: Option B

    6.
    Taylor, Woods and Hughes labeled Vicia DNA by allowing new DNA synthesis in the presence of radioactive thymine. After DNA replication (S phase of the cell cycle), it was observed that

    A. only one chromatid of a chromosome was labeled
    B. both chromatids of a chromosome were labeled
    C. both (a) and (b)
    D. neither chromatid was labeled
    Answer & Explanation
    Answer: Option B

    7.
    In DNA double helix, the two DNA chains are held together by

    A. covalent bonds between the pair of bases
    B. hydrogen bonds between the pair of bases
    C. ionic bonds between the pair of bases
    D. none of the above
    Answer & Explanation
    Answer: Option B

    8.
    The 5' and 3' numbers are related to the

    A. length of the DNA strand
    B. carbon number in sugar
    C. the number of phosphates
    D. the base pair rule
    Answer & Explanation
    Answer: Option B

    9.
    Messelsen and Stahl model of replication was called

    A. conservative replication
    B. semi-conservative replication
    C. dispersive replication
    D. Cri du Chat
    Answer & Explanation
    Answer: Option B

    9.
    Messelsen and Stahl model of replication was called

    A. conservative replication
    B. semi-conservative replication
    C. dispersive replication
    D. Cri du Chat
    Answer & Explanation
    Answer: Option B

    11.
    DNA replication takes place in which direction?

    A. 3' to 5'
    B. 5 'to 3'
    C. Randomly
    D. Vary from organism to organism
    Answer & Explanation
    Answer: Option B

    2.
    DNA gyrase in E. coli

    A. adds positive supercoils to chromosomal DNA
    B. can be inhibited with antibiotics
    C. is required only at the oriC site
    D. performs the same function as helicase in eukaryotes
    Answer & Explanation
    Answer: Option B

    13.
    In DNA, there are

    A. five bases known as adenine, guanine, thymine, tryptophan and cytosine
    B. four bases known as adenine, guanine, thymine and cytosine
    C. three bases known as adenine, guanine and cytosine
    D. only two bases known as adenine and cytosine
    Answer & Explanation
    Answer: Option B

    14.
    In DNA, guanine pairs with

    A. Adenine B. Cytosine
    C. Thymine D. Uracil
    Answer & Explanation
    Answer: Option B

    15.
    Which of the following is incorrect?

    A. In DNA double helix, two strands of the DNA are bound with each other with the bases
    B. Adenine always pairs with thymine
    C. Guanine always pairs with the cytosine
    D. None of the above
    Answer & Explanation
    Answer: Option D

    16.
    What is the only common methylation in the DNA of eukaryotes?

    A. Adenosine in GpA dinucleotides
    B. Guanosine in ApGpA trinucleotides
    C. Cytosine in CpG dinucleotides
    D. None of the above
    Answer & Explanation
    Answer: Option C

    17.
    DNAs when charged, migrate in a gel towards the

    A. positive pole
    B. negative pole
    C. will not migrate
    D. none of these
    Answer & Explanation
    Answer: Option A

    18.
    What is the approximate size (in kb) of the E. coli genome?

    A. 3000 kilobase
    B. 4500 kilobase
    C. 5500 kilobase
    D. 6500 kilobase
    Answer & Explanation
    Answer: Option B

    19.
    In the study of one experiment it was found that the value of Tm for DNA is = 40° C. If the cell has 20% GC at the above Tm, then what will be value of 'Tm' if the GC% increases to 60%?

    A. Remains same
    B. Increases
    C. Decreases
    D. Can not be compared
    Answer & Explanation
    Answer: Option B

    20.
    What is the range of melting point temperatures (Tm) for most DNA molecules?

    A. 50 to 60°C
    B. 60 to 80°C
    C. 70 to 90°C
    D. 80 to l00°C
    Answer & Explanation
    Answer: Option D
     
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