PYQ Vault

Chemistry · Textbook solutions

Biomolecules

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. Plus every board question asked from this chapter. · 29 questions

14. Biomolecules — worked examples

6 q

Solved Examples

Worked · 6
  1. Solved Ex.14.1
    An alcoholic compound was found to have molcular mass of 90 u. It was acetylated. Molecular mass of the acetyl derivative was found to be 174 u. How many alcoholic (-OH) groups must be present in the original compound?
  2. Solved Ex.14.2
    Assign D/L configuration to the following monosaccharides.
  3. Solved Ex.14.3
    Chymotrypsin is a digestive enzyme that hydrolyzes those amide bonds for which the carbonyl group comes from phenylalanine, tyrosine or tryptophan. Write the symbols of the amino acids and peptides smaller than pentapeptide formed by hydrolysis of the following hexapeptide with chymotrypsin. Gly-Tyr-Gly-Ala-Phe-Val
  4. Solved Ex.14.4
    Write down the structures of amino acids constituting the following peptide. CH3−CH(NH2)−CO−NH−CH(CH2OH)−CO−NH−CH(CH2SH)−COOH\mathrm{CH_3-CH(NH_2)-CO-NH-CH(CH_2OH)-CO-NH-CH(CH_2SH)-COOH}
  5. Solved Ex.14.5
    Draw a schematic representation of trinucleotide segment 'ACT' of a DNA molecule.
  6. Solved Ex.14.6
    Write the sequence of the complementary strand of the following portion of a DNA molecule : 5' - ACGTAC-3'

Exercises

23 q

1. Select the most correct choice.

Practice · 6
  1. Select the most correct choice.
    Ex Q.1 (i)
    CH2OH−CO−(CHOH)4−CH2OH\mathrm{CH_2OH-CO-(CHOH)_4-CH_2OH} is an example of
    1. A.
      Aldohexose
    2. B.
      Aldoheptose
    3. C.
      Ketotetrose
    4. D.
      Ketoheptose
  2. Ex Q.1 (ii)
    Open chain formula of glucose does not contain
    1. A.
      Formyl group
    2. B.
      Anomeric hydroxyl group
    3. C.
      Primary hydroxyl group
    4. D.
      Secondary hydroxyl group
  3. Ex Q.1 (iii)
    Which of the following does not apply to CH2NH2−COOH\mathrm{CH_2NH_2-COOH}
    1. A.
      Neutral amino acid
    2. B.
      L - amino acid
    3. C.
      Exists as zwitter ion
    4. D.
      Natural amino acid
  4. Ex Q.1 (iv)
    Tryptophan is called essential amino acid because
    1. A.
      It contains aromatic nucleus.
    2. B.
      It is present in all the human proteins.
    3. C.
      It cannot be synthesised by human body.
    4. D.
      It is essential constituent of enzymes.
  5. Ex Q.1 (v)
    A disulfide link gives rise to the following structure of protein.
    1. A.
      Primary
    2. B.
      Secondary
    3. C.
      Tertiary
    4. D.
      Quaternary
  6. Ex Q.1 (vi)
    RNA has
    1. A.
      A - U base pairing
    2. B.
      P-S-P-S backbone
    3. C.
      double helix
    4. D.
      G - C base pairing

2. Give scientific reasons :

Practice · 5
  1. Give scientific reasons :
    Ex Q.2 (i)
    The disaccharide sucrose gives negative Tollens test while the disaccharide maltose gives positive Tollens test.
  2. Ex Q.2 (ii)
    On complete hydrolysis DNA gives equimolar quantities of adenine and thymine.
  3. Ex Q.2 (iii)
    α\alpha - Amino acids have high melting points compared to the corresponding amines or carboxylic acids of comparable molecular mass.
  4. Ex Q.2 (iv)
    Hydrolysis of sucrose is called inversion.
  5. Ex Q.2 (v)
    On boiling egg albumin becomes opaque white.

3. Answer the following

Practice · 4
  1. Answer the following
    Ex Q.3 (i)
    Some of the following statements apply to DNA only, some to RNA only and some to both. Lable them accordingly. a. The polynucleotide is double stranded. (........) b. The polynucleotide contains uracil. (........) c. The polynucleotide contains D-ribose (........). d. The polynucleotide contains Guanine (........).
  2. Ex Q.3 (ii)
    Write the sequence of the complementary strand for the following segments of a DNA molecule. a. 5' - CGTTTAAG - 3' b. 5' - CCGGTTAATACGGC - 3'
  3. Ex Q.3 (iii)
    Write the names and schematic representations of all the possible dipeptides formed from alanine, glycine and tyrosine.
  4. Ex Q.3 (iv)
    Give two evidences for presence of formyl group in glucose.

4. Draw a neat diagram for the following:

Practice · 8
  1. Draw a neat diagram for the following:
    Ex Q.4 (i)
    Haworth formula of glucopyranose
  2. Ex Q.4 (ii)
    Zwitter ion
  3. Ex Q.4 (iii)
    Haworth formula of maltose
  4. Ex Q.4 (iv)
    Secondary structure of protein
  5. Ex Q.4 (v)
    AMP
  6. Ex Q.4 (vi)
    dAMP
  7. Ex Q.4 (vii)
    One purine base from nucleic acid
  8. Ex Q.4 (viii)
    Enzyme catalysis