Q: Which of the following equations correctly represents the overall process of aerobic cellular respiration of glucose?

$$ \mathrm{C_6H_{12}O_6} + 6\,\mathrm{O_2} \rightarrow 6\,\mathrm{CO_2} + 6\,\mathrm{H_2O} + \text{energy (ATP + heat)} $$

Question 1

Which of the following statements best explains why the oxidation of glucose during cellular respiration is considered exergonic?

Accepted Answer

Because electrons are transferred from glucose to oxygen, releasing energy as they move to a lower energy state.

Question 2

During cellular respiration, which molecule acts as the final electron acceptor in the electron transport chain in aerobic organisms?

Accepted Answer

O$$_2$$

Question 3

A patient is diagnosed with a genetic disorder that causes a defect in the enzyme phosphofructokinase. Which of the following would most likely be affected in this patient?

Accepted Answer

The rate of glycolysis would be altered, affecting the overall rate of ATP production.

Question 4

Which of the following equations correctly represents the overall process of aerobic cellular respiration of glucose?

Accepted Answer

$$ \mathrm{C_6H_{12}O_6} + 6\,\mathrm{O_2} ightarrow 6\,\mathrm{CO_2} + 6\,\mathrm{H_2O} + 	ext{energy (ATP + heat)} $$

Question 5

Which of the following best describes the role of NAD$$^+ in $$cellular respiration?

Accepted Answer

It functions as an oxidizing agent, accepting electrons during redox reactions.

Question 6

A researcher isolates mitochondria and provides them with an abundant supply of NADH, ADP, and inorganic phosphate, but no oxygen. Which of the following outcomes is most likely?

Accepted Answer

The electron transport chain will stop, and little or no ATP will be produced.

Question 7

Which of the following statements about substrate-level phosphorylation is correct?

Accepted Answer

It directly transfers a phosphate group from an organic substrate to ADP to form ATP.

Question 8

In brown fat cells of hibernating mammals, the uncoupling protein allows protons to flow back into the mitochondrial matrix without generating ATP. What is the primary benefit of this adaptation?

Accepted Answer

It generates heat to maintain body temperature during hibernation.

Question 9

Which of the following best explains why fats yield more ATP per gram than carbohydrates when oxidized in cellular respiration?

Accepted Answer

Fats have more hydrogen atoms, providing more electrons for the electron transport chain.

Question 10

A facultative anaerobe such as yeast is grown in two flasks: one with oxygen and one without. Which of the following best describes the difference in glucose consumption between the two flasks?

Accepted Answer

Yeast will consume glucose at a faster rate in the absence of oxygen to compensate for lower ATP yield.

Question 11

Which of the following is a key regulatory enzyme in glycolysis that acts as the 'pacemaker' of cellular respiration?

Accepted Answer

Phosphofructokinase

Question 12

In lactic acid fermentation, which of the following occurs?

Accepted Answer

Pyruvate is reduced directly by NADH to form lactate, regenerating NAD$$^+.$$

Question 13

Which of the following best describes the function of the electron transport chain in mitochondria?

Accepted Answer

It uses the energy from electrons to pump protons, creating a gradient used for ATP synthesis.

Question 14

Which of the following is a correct sequence of events for the flow of electrons during aerobic cellular respiration?

Accepted Answer

Glucose $$\rightarrow$$ NADH $$\rightarrow$$ Electron Transport Chain $$\rightarrow O$_2$$

Question 15

Which of the following is a reason why the exact number of ATP molecules generated from one molecule of glucose during cellular respiration is not always the same?

Accepted Answer

The type of shuttle used to transport electrons from cytosolic NADH into mitochondria can affect ATP yield.

Question 16

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation allows glycolysis to continue by regenerating NAD$$^+ in $$the absence of oxygen.

Question 17

A mutation causes a cell to lack the enzyme dehydrogenase required for the conversion of pyruvate to acetyl CoA. Which process would be directly affected?

Accepted Answer

The citric acid cycle would receive less acetyl CoA, reducing its activity.

Question 18

Which of the following best explains why glycolysis is considered one of the earliest metabolic pathways to have evolved?

Accepted Answer

It is found in nearly all organisms and occurs in the cytosol without the need for organelles.

Question 19

Which of the following is a correct description of the fate of lactate produced in human muscle cells during strenuous exercise?

Accepted Answer

It is transported to the liver, where it is converted back to pyruvate for further metabolism.

Question 20

Which of the following best describes the role of feedback inhibition in cellular respiration?

Accepted Answer

It prevents the overproduction of ATP by inhibiting key enzymes when energy is sufficient.

Cellular Respiration and Fermentation: Pathways of Energy Harvest

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