Model Answers Quiz 2

7/27/2019 Model Answers Quiz 2

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MODERN BIOLOGY (BT 101)

Quiz 2, 13.04.2011

1. Which of the following statements is FALSE?

A) Glycolysis is controlled by allosteric inhibitionB) Pyruvic acid is an end-product of fermentation in absence of oxygen

C) Pyruvate dehydrogenase is a multienzyme complex

Ans: Pyruvic acid is an end-product of fermentation in absence of oxygen

Hint: Slides 19 and 20 ofhttp://shilloi.iitg.ernet.in/~biotech/BT101/metabolism.pdf

2. Enzymes catalyzing oxidative phosphorylation are primarily present in:

A) Inner Mitochondrial MembraneB) Endoplasmic reticulum

C) Ribosomes

Ans: Inner Mitochondrial Membrane

Hint: Slide 41, http://shilloi.iitg.ernet.in/~biotech/BT101/metabolism.pdf

3. Glycolysis is increased by:

A) Glucagon B) Heparin C) Insulin

Ans: Insulin

Hint: Slide 27, 30, 31, http://shilloi.iitg.ernet.in/~biotech/BT101/metabolism.pdf

4. Fructose-2, 6-bisphosphate is formed by the action of

A) Phosphofructokinase-1

B) Phosphofructokinase-2C) Fructose-1, 6-bisphosphatase

Ans: Phosphofructokinase-2


5. X45 is a small peptide produced by a bacterium which can create a pore in the mitochondrial membranes through

which H+ can flow. Treatment of human cells growing in a flask with X45 will lead to:

A) Inhibition of Glycolysis in these cellsB) Reduced energy production in these cells

C) Massive growth of these cells

Ans: Reduced energy production in these cells



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6. A protein gets degraded by hydrolysis which follows first order kinetics. The first order rate constant for degradation

of this protein is 0.035 per hr. Calculate the half life of this protein.

A) Approximately 50 hr B) Approximately 20 hr C) Approximately 5 hr

Ans: Approximately 20 hr

Hint: Slide 5, http://shilloi.iitg.ernet.in/~biotech/BT101/kinetics1.pdf

7. The dissociation constant of a ligand binding to a receptor is 10

-9

M. The rate constant for dissociation is 10

-4

1/sec.What is the association rate constant for this ligand?

A) 105

1/M.sec B) 105

1/sec C) 10-13

1/sec

Ans: 105 1/M.sec

Hint: Slide 7, http://shilloi.iitg.ernet.in/~biotech/BT101/kinetics2.pdf

8. Which of the following statements is FALSE?

A) Decrease in pH reduces oxygen binding affinity of HemoglobinB) Hemoglobin can be in two different states with varying affinity for oxygen

C) Formation of Carbamate increases oxygen binding affinity of Hemoglobin

Ans: Formation of Carbamate increases oxygen binding affinity of Hemoglobin

Hint: slide 20, http://shilloi.iitg.ernet.in/~biotech/BT101/kinetics4.pdf

9. The oxygen binding behavior of Hemoglobin in presence /absence of a drug G67 is shown here. Which of the

following statements is TRUE?

A) G67 increases the affinity of Hemoglobin for Oxygen

B) G67 decreases the affinity of Hemoglobin for OxygenC) G67 increases the number of oxygen molecules that can bind to Hemoglobin

Ans: G67 decreases the affinity of Hemoglobin for Oxygen



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10. Lineweaver-Burk plots for two enzymes E1 and E2 are shown bellow. Both of these enzymes follow Michaelis

Menten kinetics. MichaelisMenten constants for E1 and E2 are K1 and K2 respectively. Which of the following is

TRUE?

A) K1 > K2 B) K1 < K2 C) K1 = K2

Ans: K1 > K2


11. Which RNA molecule is small and has a very specific secondary and tertiary structure so that it can bind an amino

acid at one end and messenger RNA at the other?

A) RNA nucleotide B) transfer RNA C) ribosomal RNA

Ans: transfer RNA

12. The defective protein causing sickle cell anemia is caused by the substitution of one nucleotide in the gene HBB on

chromosome number 11, resulting in the change of the amino acid glutamic acid to valine. This is an example of what

kind of mutation?

A) missense B) nonsense C) frameshift

Ans: missense

13. HIV, the virus that causes AIDS, infects only cells with the CD4 receptor protein in their outer cell membranes.Why do some cells in the human body have the CD4 protein while others do not?

A) Cells with CD4 protein have mutated.

B) The CD4 gene is active only in certain cells.

C) Cells with CD4 proteins are aneuploid.

Ans: The CD4 gene is active only in certain cells.

14. Normally, cells lose a bit of the tips of their chromosomes each time they go through a cell cycle. When the tips of

the chromosomes degrade too much the DNA can no longer be replicated and the cell can no longer divide. Cancer

cells avoid this problem and continue to divide indefinitely by producing:

A) DNA polymerase B) RNA polymerase C) Telomerase

Ans: telomerase


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15. Sequencing of a 5 base-long segment of DNA using the Sanger method produced the set of DNA fragments listed

below. Each fragment ends with the fluorescent dideoxynucleotide indicated by the letters A, C, G, or T. Construct the

sequence of this complementary strand and determine the sequence of the ORIGINAL DNA molecule.

Complementary DNA Fragments produced during sequencing:

O-O-C O-O-O-O-G O-T O-O-O-A A

Choose the Original DNA Sequence

A) 5 A-T-C-A-G 3 B) 5 T-A-G-T-C 3 C) 5 C-T-G-A-T 3

Ans : 5 C-T-G-A-T 3

16. Shania Twain produced a two-disk set of original songs. One disk is a collection of nineteen songs, performed in a

country style. The other disk includes the same nineteen songs in the same order, but performed in a "pop" style. If we

think of music CDs as being analogous to chromosomes, these two disks would be analogous to

____________________

A) sister chromatids

B) different numbered chromosomesC) homologous chromosomes

Ans: homologous chromosomes

17. One complete turn of the double helix contains 10 pairs of bases and is 3.4 nm long. What is the approximate

length of the DNA coding sequence of lysozyme, a protein of 129 amino acids?

A) 132 nm B) 113 nm C) 129 nm

Ans: 132nm

18. Neuromuscular junction is a specialised

A) electric synapse B) chemical synapse C) ephaptic coupling

Ans: chemical synapse

19. The diagram shows the structure of a neuromuscular junction. Identify structure G

A) Post synaptic membrane B) Synaptic vesicle C) Motor neuron

Ans: Post synaptic membrane

G


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20. The resting membrane potential of a motor neuron at a neuromuscular junction is around -50mV. What would

happen to the action potential when they are depolarised?

A) increases B) decreases C) do not change

Ans: increases

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Model Answers Quiz 2