Question 1

Which structural feature of the inner mitochondrial membrane is most directly responsible for its increased surface area and enhanced capacity for ATP production?

Accepted Answer

Cristae folds

Question 2

Matrix proteins are imported into the mitochondrion from the cytoplasm. Which sequence of events correctly describes this process?

Accepted Answer

Proteins are unfolded by chaperones, pass through TOM and TIM, and require ATP hydrolysis for import

Question 3

During pyruvate oxidation, which enzyme complex catalyzes the conversion of pyruvate to acetyl CoA, and what are the main products?

Accepted Answer

Pyruvate dehydrogenase complex; NADH, CO$$_2$$, and acetyl CoA

Question 4

Which of the following best explains why aerobic respiration is more efficient than fermentation?

Accepted Answer

Aerobic respiration uses oxygen as the final electron acceptor, allowing complete oxidation of glucose

Question 5

In the citric acid cycle, the exergonic hydrolysis of the thioester bond in succinyl CoA is coupled to the synthesis of which molecule in animal cells?

Accepted Answer

GTP

Question 6

Which of the following is a correct sequence of the five stages of cellular respiration?

Accepted Answer

Glycolysis, pyruvate oxidation, citric acid cycle, electron transport chain, oxidative phosphorylation

Question 7

Beta-oxidation of fatty acids produces which key molecule that enters the citric acid cycle?

Accepted Answer

Acetyl CoA

Question 8

Which of the following statements about mitochondrial DNA is correct?

Accepted Answer

It is circular and encodes rRNAs, tRNAs, and some inner membrane protein polypeptides

Question 9

Allosteric regulation of the citric acid cycle is primarily achieved by which molecule acting on dehydrogenases?

Accepted Answer

NADH

Question 10

A patient presents with a mitochondrial disorder affecting the import of matrix proteins. Which step is most likely impaired?

Accepted Answer

Hydrolysis of ATP required for translocation through TOM and TIM complexes

Question 11

Which of the following best describes the role of the proton gradient in mitochondria?

Accepted Answer

It is harnessed to synthesize ATP during oxidative phosphorylation

Question 12

Which equation correctly represents the overall reaction for pyruvate oxidation?

Accepted Answer

$$\mathrm{Pyruvate} + \mathrm{NAD}^+ + \mathrm{CoA} \rightarrow \mathrm{Acetyl\ CoA} + \mathrm{NADH} + \mathrm{CO}_2$$

Question 13

In a cell with high ATP levels, what is the expected effect on pyruvate dehydrogenase (PDH) activity?

Accepted Answer

PDH is inactivated by phosphorylation

Question 14

Which of the following is NOT a product of the citric acid cycle per acetyl CoA molecule?

Accepted Answer

2 ATP

Question 15

Fatty acid beta-oxidation involves repeated cycles of which sequence of reactions?

Accepted Answer

Oxidation, hydration, oxidation, thiolysis

Question 16

Which of the following statements about mitochondrial location in cells is correct?

Accepted Answer

Mitochondria are located near regions where energy is required, such as flagella and cilia

Question 17

Which process allows mitochondria to be isolated and their function to be determined experimentally?

Accepted Answer

Differential centrifugation

Question 18

Which of the following is a correct statement about the permeability of the mitochondrial membranes?

Accepted Answer

The inner membrane is more selective and contains cristae to increase surface area

Question 19

Which of the following best explains why fats yield more energy than carbohydrates upon complete oxidation?

Accepted Answer

Fats are more highly reduced, allowing more electrons to be transferred to NAD$$^+$$ and FAD during beta-oxidation

Mitochondrial Structure, Function, and Cellular Respiration

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