Important Question Gate Life Science

Q1. Four proteins (P1, P2, P3 and P4) have 17, 10, 21 and 14 percent hydrophobic amino-acids respectively. The order of precipitation of these proteins using ammonium sulphate will be

1. P3, P1, P4, P2
2. P3, P1, P2, P4
3. P2, P4, P3, P1
4. P2, P4, P1, P3

Answer: A

Q2. Which one of the following pairs of amino-acids in the protein has high propensity to take up the α-helix conformation?

1. Gly-Asp
2. Pro-His
3. Gly-Pro
4. Ala-Arg

Answer: D

Q3. Which one of the following closely defines ‘Molten Globule’ state of a protein?

1. State with high degree of secondary structure and loss of tertiary structure
2. State with complete loss of secondary structure
3. Completely unfolded state
4. Loss of quaternary structure

Answer: A

Q4. Which one of the following amino-acids has highest fluorescence quantum yield (𝜙) in aqueous solution?

1. Tyrosine
2. Tryptophan
3. Phenylalanine
4. Histidine

Answer: B

Q5. Which one of the following compounds does NOT block electron transport?

1. Cyanide
2. Rotenone
3. Oligomycin
4. Antimycin A

Answer: C

Q6. The pair of amino-acids which does NOT undergo post-translational modification is

1. Asn-His
2. Tyr-Ser
3. Asn-Ser
4. Ala-Gly

Answer: D

Q7. Upon stimulation of a eukaryotic cell, the intracellular calcium (Ca 2+ ) is released from

1. Endoplasmic reticulum
2. Nucleus
3. Peroxisome
4. Mitochondria

Answer: A

Q8. Leguminous plants maintain a very low concentration of free oxygen in their root nodules because

1. the nitrogen fixing bacteria living in the root nodules are anaerobic
2. of binding of oxygen to leghemoglobin
3. reductase enzyme of the nitrogenase complex helps in removal of O2
4. nitrogenase enzyme of the nitrogenase complex helps in removal of O2

Answer: B

Q9. The membrane of mature B cells have

1. both IgG and IgM
2. both IgG and IgD
3. both IgM and IgE
4. both IgM and IgD

Answer: D

Q10. An amino-acid has one proton donating group in the side chain (R). The pK COOH , pK NH2 and pK R values for this amino-acid are 2.19, 9.67 and 4.25, respectively. Which one of the following statements about this amino-acid is CORRECT?

1. Majority of the molecules will have a net charge of -1 at pH of 7.0
2. Majority of the molecules will have a net charge of 0 at pH of 4.25
3. All the molecules will have a deprotonated R group at pH of 3.22
4. During titration with a strong base, deprotonation will start with the R group

Answer: A