In the name of ALLAH, the most beneficient, the most merciful

Biochemistry-I (BIO202)

Multiple Choice Questions (MCQs)

Objective Questions

  1. Z-DNA have a

    1. Zig-Zag apperarance
    2. Double helical nature
    3. uracil base
    4. single stranded nature
  2. A DNA segment contains 100 Adenine and 100 cytosines, how many nucleotides are present in the segment?

    1. 50
    2. 100
    3. 200
    4. 400
  3. ATP is a

    1. nucleoside
    2. nucleotide
    3. vitamin
    4. nucleic acid
  4. Which one of the following is true of the pentoses found in nucleic acids?

    1. C-5 and C-1 of the pentose are joined to phosphate groups.
    2. The bond that joins nitrogenous bases to pentoses is an O-glycosidic bond.
    3. The pentoses are always in the β-furanose forms.
    4. The straight-chain and ring forms undergo constant interconversion.
  5. Chromatin is composed of

    1. nucleic acids and protein
    2. nucleic acids only
    3. proteins only
    4. None of the given
  6. According to Chargaff's Rules
    which one is not correct

    1. adenine equals the amount of thymine.
    2. guanine equals the amount of cytosine
    3. total amount of purines equals the total amount of pyrimidines
    4. guanine equals the amount of thymine
  7. Nucleosomes can be packed more tightly to form a polynucleosome also called a nucleofilament or a ________nm fiber.

    1. 10
    2. 30
    3. 50
    4. 100
  8. There are ________ classes of histones

    1. 3
    2. 5
    3. 7
    4. 9
  9. In living cells, nucleotides and their derivatives can serve as:

    1. carries of metabolic energy.
    2. enzyme cofactors.
    3. intracellular signals.
    4. All of the given
  10. Disruption of DNA can occur in the laboratory with alteration in

    1. PH
    2. salt concentration
    3. heated above 80°C
    4. All of the given
  11. Adenosine 3'-phosphate-5'-phosphosulfate is the ________ donor.

    1. Sulfate
    2. Phosphate
    3. Adenosine
    4. None of the given
  12. Under appropriate conditions DNA will form a hybrid with a complementary ________.

    1. DNA
    2. RNA
    3. Both DNA and RNA
    4. None of the given
  13. The DNA wrapped around the nucleosome core is continuous and joins one nucleosome core to the next -the linker DNA
    this 50 bp DNA is complexed with the fifth type of histone. ________

    1. H1
    2. H2A, H2B
    3. H3
    4. H4
  14. S-adenosylmethionine is a ________ group donor.

    1. Methyl
    2. Phosphate
    3. Adenosine
    4. Sulfate
  15. The complex folding of large chromosomes within eukaryotic chromatin and bacterial nucleoids is generally considered ________.

    1. primary structure
    2. secondary structure
    3. tertiary structure
    4. All of the given
  16. The difference between thymine and uracil is:

    1. one methylene group on the pyrimidine ring
    2. one methyl group on the pyrinidine ring.
    3. one hydroxyl group on the ribose ring.
    4. one amine group on the pyrimidine ring.
  17. The ________ strand is called Template strand while

    1. 5'-3
    2. 3'-5
    3. 3'-3
    4. 5'-5
  18. histones are ________ charged

    1. positively
    2. negatively
    3. neutral
    4. None of the given
  19. The DNA oligonucleotide abbreviated pATCGAC:

    1. has seven phosphate groups.
    2. has a hydroxyl at its 3' end.
    3. has a phosphate on its 3' end.
    4. has an A at its 3' end.
  20. single-stranded DNA has a ________ relative absorbance at 260nm wavelength than does double-stranded DNA.

    1. lower
    2. higher
    3. equal
    4. None of the given
  21. Around structural core of the nucleosome, a segment of the DNA double helix is wound nearly twice-approximately ________.

    1. 100bp
    2. 120bp
    3. 140bp
    4. 160bp
  22. DNA that is not copied during the synthesis of mRNA is also called as

    1. Non Template
    2. coding strand
    3. mRNA-like strand
    4. All of the given
  23. When linked to vitamins nucleotides are structural components of several essential coenzymes, for example,

    1. coenzyme A
    2. coenzyme B
    3. coenzyme C
    4. coenzyme D
  24. Find the correct statement about phosphodiester linkage between adjacent nucleotides in nucleic acids

    1. 3'-phosphate of one nucleotide joins the 3'-hydroxyl of the next nucleotide
    2. 3'-phosphate of one nucleotide joins the 5'-hydroxyl of the next nucleotide
    3. 5'-phosphate of one nucleotide joins the 5'-hydroxyl of the next nucleotide
    4. 5'-phosphate of one nucleotide joins the 3'-hydroxyl of the next nucleotide
  25. Any regular, stable structure taken up by some or all of the nucleotides in a nucleic acid can be referred to as

    1. primary structure
    2. secondary structure
    3. tertiary structure
    4. All of the given
  26. Purine base found in RNA is

    1. Cytosine
    2. Thymine
    3. Guanine
    4. Uracil
  27. The sugar molecule present in nucleotide is

    1. Triose
    2. Tetrose
    3. Pentose
    4. Hexose
  28. A short length of DNA molecule has 80 thymine and 80 guanine bases. The total number of nucleotide in the DNA fragment is

    1. 160
    2. 40
    3. 320
    4. 640
  29. Separation of the two strands of the double helix when ________ bonds between the paired bases are disrupted.

    1. phosphodiester
    2. hydrogen
    3. glycosilic bond
    4. None of the given
  30. Nucleic acids are a polymer of nucleotide monomeric units. Each nucleotide consists of

    1. base-.sugar.-OH
    2. sugar.-phosphate
    3. base-.sugar.-phosphate
    4. sugar.-OH
  31. Which of the following is a palindromic sequence?

    1. AGGTCC
      TCCAGG
    2. CCTTCC
      GCAAGG
    3. GAATCC
      CTTAGG
    4. GGATCC
      CCTAGG
  32. Eukaryotic DNA is associated with tightly bound basic ________, called histones.

    1. lipid
    2. proteins
    3. carbohydrates
    4. nucleic acid
  33. The phosphodiester bonds that link adjacent nucleotides in both RNA and DNA:

    1. always link A with T and G with C.
    2. are susceptible to alkaline hydrolysis
    3. form between the planar rings of adjacent bases.
    4. join the 3' hydroxyl of one nucleotide to the 5'hydroxyl of the next.
  34. When DNA is heated, the temperature at which ________ of the helical structure is lost is defined as the melting temperature.

    1. one half
    2. two half
    3. three half
    4. complete
  35. higher GC base pairs increases Tm, because, with three hydrogen bonds, require ________ heat energy to dissociate than AT base pairs.

    1. less
    2. more
    3. equal
    4. None of the given
  36. A phosphodiester bond is present in

    1. Nucleic acids in a nucleotide
    2. Monosaccharides in a polysaccharide
    3. Amino acids in a polypeptide
    4. Fatty acids in a diglyceride
  37. These ________ bonds, plus the van der Waals and hydrophobic interactions between the adjacent stacked bases, stabilize the structure of the double helix.

    1. phosphodiester
    2. nitrogen
    3. hydrogen
    4. None of the given
  38. DNA replication is

    1. Conservative
    2. Non-conservative
    3. Semi-conservative
    4. None of the given
  39. The "energy carrier" ATP is an example of a(n):

    1. deoxyribonucleoside triphosphate
    2. di-nucleotide
    3. ribonucleotide
    4. ribonucleoside triphosphate
  40. Compounds that generate nitrous acid (such as nitrites, nitrates, and nitrosamines) change DNA molecules by:

    1. Breakage of phosphodiester bonds
    2. Deamination of bases
    3. Depurination
    4. Formation of thymine dimers
  41. Certain anticancer drugs, exert their cytotoxic effect by intercalating into
    the ________ groove of the DNA double helix, thus interfering with RNA and DNA synthesis

    1. narrow
    2. major
    3. phosphate backbone
    4. bases
  42. DNA model was presented by Watson and Crick in ________.

    1. 1951
    2. 1953
    3. 1955
    4. 1957
  43. Which one is example of coenzymes

    1. FAD
    2. NAD+
    3. NADP+
    4. All of the given
  44. In a double-stranded nucleic acid, cytosine typically base-pairs with:

    1. Adenosine
    2. Guanine
    3. Inosine
    4. Thymine
  45. The Tm of DNA is influenced by

    1. higher the content of GC base pairs
    2. base composition of the DNA
    3. salt concentration of the solution
    4. All of the given
  46. Nucleotides are composed of

    1. A nitrogenous base (purine or pyrimidine)
    2. A pentose monosaccharide
    3. One, two, or three phosphate groups
    4. All of the given
  47. RNA duplexes are ________ stable than DNA duplexes.

    1. more
    2. less
    3. equal
    4. None of the given
  48. Nucleotides also serve as carriers of activated intermediates in the synthesis of ________.

    1. Carbohydrates
    2. Lipids
    3. Proteins
    4. All of the given
  49. Nucleoside contains

    1. base-sugar
    2. base-phosphate
    3. base-sugar-phosphate
    4. sugar-phosphate