Question

20. Inhibition of the enzyme malate dehydrogenase (MDH) from Plasmodium falciparum is a potential novel treatment for malaria. MDH catalyzes the conversion of malate to oxaloacetate. Which metabolic pathway in P. falciparum will be directly affected if MDH is inhibited? a. Glycolysis b. The electron transport chain c. The citric acid cycle d. Alcohol fermentation 21. Which of the following compounds has the greatest amount of energy for a cell? a. CO b. ATP C. Glucose d. Lactic acid e. NADH 22. Escherichia coli is a facultative anaerobe. Imagine that two cultures of E. coli have been growing in glucose broth for 1 day. One culture was grown with Oz and the other was grown without 02. Which culture, if any, used more glucose? a. The culture grown with Oz used more glucose b. The culture grown without O, used more glucose c. Both cultures used an equal amount of glucose 23. Numerical answer: Not every organism can create 38 ATP from a single molecule of glucose. Organisms that carry out anaerobic respiration and use molecules other than oxygen for respiration are usually less efficient than aerobes. If an organism made 2 ATP per NADH and 1.5 ATP per FADH, how much ATP would this organism make from one molecule of glucose? 24. The explosive TNT (trinitrotoluene) is easily handled by people who use it. For example, it can be melted in a frying pan without it exploding. To cause TNT to explode, a smaller detonation must occur usually through the use of a percussion or blasting cap. Another explosive, Nitrogen Triiodide is much more dangerous to handle. Nitrogen triiodide is a contact explosive, and will detonate if it is simply dropped onto a surface from a height of a few feet. The reason why TNT is more stable than nitrogen triiodide is because: a. TNT has a higher activation energy compared to nitrogen triiodide b. TNT has a lower activation energy compared to nitrogen triiodide CTNT has more chemical potential energy than nitrogen trijodide d. TNT has less chemical potential energy compared to nitrogen triiodide

Answer 1

20. Correct answer (C ) (citric acid cycle)

The enzyme Malate dehydrogenase or (MDH) reversibly catalyzes the oxidation of malate to oxaloacetate. This occurs with the reduction of NAD+ to NADH. This reaction is part of the steps at the end of citric acid cycle.

21. Correct answer (C ) (glucose )

38 number of ATP molecules can be produced with the oxidation of one glucose molecule during cellular respiration. Hence ATP which is the source of energy for a cell can be produced the most from one molecule of glucose.

22.Correct answer (b) (the culture without oxygen uses more glucose )

In the absence of oxygen, glucose is consumed at a much higher rate. This happens because less usable energy can be harvested from glucose in the absence of oxygen. In the presence of oxygen, a glucose molecule yields about 30 ATP molecules. Whereas in the absence of oxygen only 2 ATP molecules can be produced per glucose molecule.

23. For a process of anaerobic respiration, production of ATP is always 2 as glucose is not fully converted into energy and no oxidative phosphorylation of pyruvate occur.

Hence a detail about aerobic respiration is given here, where the number of NADH and FADH2 production and ATP produced by them is shown.

Glycolysis preparatory phase :

Produces 2 ATP

Oxidative phosphorylation :

Produces 2 NADH (each producing 2 ATP) hence 4ATP produced.

Oxidative decarboxylation of pyruvate :

Produces 2 NADH (each producing 2 ATP) hence 4ATP produced

Krebs cycle:

Produces 6 NADH (each producing 2 ATP) and 2FADH2 (each producing 1.5 ATP) hence 12+3 ATP=15 ATP produced

Hence total number of ATP produced in this reaction is 2+4+4+15 = 25 ATP molecules form one glucose molecule.

24.Correct answer (a) TNT has higher activation energy than nitrogen triiodide .

TNT is a stable explosive because it needs a higher energy for its activation or ignition. Whereas nitrogen tritiodide is a very sensitive explosive with an very low activation energy that it it gets activated even from simple triggers like touch.

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