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15) An apoenzyme + cofactor(s) - a) Inhibitor b) active site c) substrate d) holoenzyme 16) Aspartate-transcarbamylase is an enveloved in a pathway that may produces molecule called Cytidine triphosphate. Cytidine triphosphate can bind to anot t o this enzyme, rendering the active site nonfunctional. This is an example of a) ATP hydrolysis b) competitive inhibition c) feedback inhibition d) allosteric activation 17) Which of the following is false regarding fermentation? a) fermentation occurs in the absence of the respiratory final electron acceptor b) fermentation regenerates NAD+. c) fermentation generates ATP via oxidative phosphorylation. d) the Kreb's cycle and electron transport chain are not involved in fermentation 18) The conversion of glucose-6-phosphate to fructose 1,6-bisphosphate has a positive delta G (+1.7 kj/mol). This reaction is: a) spontaneous and exergonic b) spontaneous and endergonic c) not spontaenous and exergonic d) not spontaneous and endergonic

Answer 1

Q.15. Answer- d. Holoenzyme

Explanation- apoenzyme is incomplete and inactive form of enzyme that lacks cofactor. When cofactor is attached to apoenzyme the enzyme become complete and catalytically active enzyme known as holoenzyme.

Q.16. Answer- c. Feedback inhibition

Explanation- In the mechanism of feedback inhibition end product of pathway inhibits the allosteric enzyme of the same pathway by binding with enzymes allosteric site and inhibits enzymes activity. In this example, cytidine triphosphate binds to allosteric site of aspartate transcarbamoylase and makes enzyme nonfunctional so that this is example of feedback inhibition.

Q.17. Answer-d. The Krebs cycle and electron transport chain are not involved in fermentation

Explanation- In fermentation pyruvate is converted into ethanol or lactate and NAD+ is produced with is used as electron acceptor for glycolysis. Pyruvate does not converted to acetyl-CoA because the process is anaerobic and Krebs cycle and electron transport chain not occurs. Bacteria ferments nutrients anaerobically to produce ATP.

Q.18. Answer- d. Non-spontaneous and endergonic

Explanation- when glucose 6-phosphate is converted into fructose1,6-bisphosphate , the change in Gibbs free energy is +1.7kj/mol . The positive value of Gibbs free energy indicates that reaction is endergonic that means energy is required by the reaction and this reaction is non-spontaneous that is depending on enzymes.