CSIR Life Sciences Biochemistry MCQ Unit-1 Molecules and their Interaction Relevant to Biology
1. The ionic strength of a 0.2 M Na2HPO4 solution will be (Dec 2015)
a. 0.2 M
b. 0.4 M
c. 0.6 M
d. 0.8 M
μ is Ionic strength, Ci is the molar concentration of any ion in solution and zi is its valence.
Ans: c. 0.6 M
2. A cell line deficient in salvage pathway for nucleotide biosynthesis was fed with medium containing 15N labelled amino acids. Purines were then extracted. Treatment with which one of the following amino acids is likely to produce 15N labelled purines? (Dec 2015)
a. Aspartic acid
Ans: a. Aspartic acid or Glycine or Glutamine
3.Enzymes accelerate a reaction by which one of the following strategies? (dec 2015)
a. Decreasing energy required to form the transition state.
b. Increasing kinetic energy of the substrate.
c. Increasing the free energy difference between substrate and the product.
d. Increasing the turn over number of enzymes.
Ans: a. Decreasing energy required to form the transition state.
4.Coupling of the reaction centers of oxidative phosphorylation is achieved by which one of the following? (dec 2015)
a. Making a complex of all four reaction centers.
b. Locating all four complexes in the inner membrane.
c. Ubiquinones and cytochrome C.
d. Pumping of protons.
Ans: c. Ubiquinones and cytochrome
5.The genome of a bacterium is composed of a single DNA molecule which is 109 bp long. How many moles of genomic DNA is present in the bacterium [Consider Avogadro No= 6 x 10 23] (dec 2015)
a. 1/6 x 10 -23
b. 1/6 x 10 -14
c. 6 x 10 14
d. 6 x 10 23
Ans: a. 1/6 x 10 -23
6. The solubility of gases in water depends on their interaction with water molecules. Four gases i.e. carbon dioxide, .oxygen, sulphur dioxide and ammonia are dissolved in water. In terms of their solubility which of the following statements is correct? (Jun, 2016)
a . Ammonia > Oxygen > Sulphur dioxide > Carbon dioxide
b. Oxygen > Carbon dioxide > Sulphur dioxide > Ammonia
c. Sulphur dioxide > Oxygen > Ammonia > Carbon dioxide
d. Ammonia > Sulphur dioxide > Carbon dioxide > Oxygen
Ans: d. Ammonia > Sulphur dioxide > Carbon dioxide > Oxygen
7. Penicillin acts as a suicide substrate. Which one of the following steps of catalysis does a suicide inhibitor affect?( Jun, 2016)
Ans: c. k3
8.Which of the following is NOT true for cholesterol metabolism? (Jun, 2016)
a. HMG-CoA reductase is the key regulator of cholesterol biosynthesis.
b. Biosynthesis takes place in the cytoplasm.
c. Reduction reactions use NADH as cofactor.
d. Cholesterol is transported by LDL in plasma.
Ans:c. Reduction reactions use NADH as cofactor.
9. The -COOH group of cellular amino acids can form which of the following bonds inside the cell? ( Jun, 2016)
1. Ether and ester bonds.
2. Ester and amide bonds.
3. Amide and ether bonds.
4. Amide and carboxylic anhydride bonds
Ans: 2. Ester and amide bonds.
10. Choose the most appropriate pH at which the net charge is zero for the molecule from the data shown below : (Dec, 2016)
Ans: b. 2.91
11. Excess oxygen consumed after a vigorous exercise is (Dec, 2016)
a. to pump out lactic acid from muscle.
b. to increase the concentration of lactic acid in muscle.
c. to reduce dissolved carbon dioxide in blood.
d. to make ATP for gluconeogenesis.
Ans: d. to make ATP for gluconeogenesis.
12. The gel to liquid crystalline phase transition temperature in phosphatidyl choline (PC) lipids composed of dioleoyl (DO), dipalmitoyl (DP), disteroyl (DS) and palmitoyl oleoyl (PO) fatty acids in increasing order will be (Dec, 2016)
a. DOPC > DPPC > POPC > DSPC
b. DSPC > DPPC > POPC > DOPC
c. DPPC > DSPC > DOPC > POPC
d. POPC > DPPC > DOPC > DSPC
Ans: b. DSPC > DPPC > POPC > DOPC