Question

5. Which sequence illustrates the order of the steps from food to biochemically useful energy? (2 points)

A) digestion; citric acid cycle; ATP production; acetyl-SCoA production B) digestion; citric acid cycle; acetyl-SCoA production; ATP production C) citric acid cycle; digestion; acetyl-SCoA production; ATP production D) digestion; acetyl-SCoA production; citric acid cycle; ATP production E) digestion; acetyl-SCoA production; ATP production; citric acid cycle

6. When electrons are lost during a metabolic oxidation: (2 points)

A) they go off into the environment B) they are neutralized by protons C) they are picked up by a coenzyme D) carbon dioxide is always given off

7. When rotenone is added to actively respiring mitochondria, the ratio of NADH to NAD+ increases, but the FADH2/FAD ratio remains unchanged. At what step is the system being inhibited? (2 points)

8. Which of the following is not true of the citric acid cycle? (2 points)

A) All enzymes of the cycle are located in the cytoplasm, except succinate dehydrogenase, which is bound to the inner mitochondrial membrane. B) In the presence of malonate, one would expect succinate to accumulate. C) Oxaloacetate is used as a substrate but is not consumed in the cycle. D) Succinate dehydrogenase channels electrons directly into the electron transfer chain. E) The condensing enzyme is subject to allosteric regulation by ATP and NADH. 9. The oxidative decarboxylation of α-ketoglutarate proceeds by means of multistep reactions in which all but one of the following cofactors are required. Which one is not required? (2 points) A) ATP B) Coenzyme A C) Lipoic acid D) NAD+ E) Thiamine pyrophosphate

Answer 1

Ans 5) Correct sequence is : Digestion -> acetyl-CoA production -> citric acid cycle -> ATP production. So, option D is correct answer.

Explanation:

After digestion of food, the resulting simpler compound is glucose which gets metabolized to produce ATP. Firstly, the glucose is oxidized partially into pyruvate by Glycolysis, then the pyruvate is converted to acetyl-CoA by Pyruvate dehydrogenase. Acetyl-CoA then gets completely oxidized by Citric acid cycle. High energy molecules FADH₂ and NADH are produced in the citric acid cycle and then these are utilized by Electron transport chain and ATP synthase to form ATP molecules. The entire process is called cellular respiration.