Question 1

Which molecule is the final electron acceptor in respiration? ​

Accepted Answer

In aerobic respiration, oxygen (O2) is the final electron acceptor, which combines with hydrogen ions to form water (H2O). This process generates a large amount of ATP through oxidative phosphorylation.

Question 2

Ultimately, the carbon molecules in pyruvate end up in which molecule? ​

Accepted Answer

The answer of Ultimately, the carbon molecules in pyruvate end...

Question 3

Which of these molecules has the most potential energy? ​

Accepted Answer

The answer of Which of these molecules has the most...

Question 4

Citrate synthase, the first enzyme in the citric acid cycle, is regulated by ATP concentrations. Why is early regulation of ATP production the most beneficial method for the cell? ​

Accepted Answer

Regulating the citric acid cycle at its initial step through citrate synthase allows the cell to efficiently manage its resources. By controlling the entry point into the cycle, the cell can prevent unnecessary consumption of acetyl-CoA and other substrates when ATP levels are high, thus conserving energy and resources. This is more efficient than regulating later steps, as it prevents the initiation of a cycle that would use up substrates without the need for more ATP.

Question 5

For every glucose molecule that goes through cellular respiration, how many carbon atoms are fully oxidized to CO₂ in the citric acid cycle?

Accepted Answer

In the citric acid cycle, each pyruvate molecule from glycolysis is broken down into CO2 and acetyl-CoA, which has two carbon atoms. In the citric acid cycle, each acetyl-CoA molecule goes through several reactions and ultimately results in the release of two CO2 molecules, meaning that four carbon atoms are fully oxidized to CO2 per glucose molecule undergoing cellular respiration. Therefore, the answer is D) 4.

Question 6

A toxic substance has been found to inhibit glucose transport into mammalian cells. If this substance is administered to a hamster, the likely cause of death would be a lack of ____ production. ​

Accepted Answer

Glucose transport into mammalian cells requires ATP as it is an energy-dependent process. Inhibition of glucose transport would lead to a lack of ATP production, which is crucial for cell metabolism and survival. Therefore, the likely cause of death in a hamster administered with the toxic substance would be a lack of ATP production.

Question 7

What is the fate of CoA after it delivers an acetyl group into the citric acid cycle? ​

Accepted Answer

After delivering an acetyl group into the citric acid cycle, CoA is released and becomes available to be recharged with another acetate. This allows for a continuous cycle of acetyl-CoA entering the citric acid cycle for energy production.

Question 8

What is the function of NADH and FADH₂?

Accepted Answer

NADH and FADH2 both provide electrons to the electron transport chain, which is crucial for the production of ATP through oxidative phosphorylation.

Question 9

Which molecule(s)is/are responsible for delivering the high energy electrons from the citric acid cycle to the electron transfer system? ​

Accepted Answer

Both NADH and FADH2 are responsible for delivering high-energy electrons from the citric acid cycle to the electron transport chain.

Question 10

Per molecule of glucose, oxidation occurs ____ times during the conversion of pyruvate to acetyl CoA. ​

Accepted Answer

​During the conversion of pyruvate to acetyl CoA, each molecule of pyruvate is oxidized twice, resulting in the production of two molecules of CO2 and two molecules of NADH per glucose molecule. Therefore, oxidation occurs two times per molecule of glucose.

Question 11

The enzyme succinate dehydrogenase, located in the inner mitochondrial membrane, is directly involved in ____. ​

Accepted Answer

Succinate dehydrogenase is involved in the citric acid cycle where it catalyzes the oxidation of succinate to fumarate, and it is also part of the electron transfer system as Complex II, where it participates in transferring electrons to the electron transport chain.

Question 12

Which molecule is responsible for carrying the acetyl group from pyruvate into the citric acid cycle? ​

Accepted Answer

CoA (Coenzyme A) is responsible for the transfer of the acetyl group from pyruvate into the citric acid cycle, forming acetyl-CoA.

Question 13

What is directly responsible for pumping protons out of the mitochondrial matrix? ​

Accepted Answer

Protein complexes I, III, and IV are directly responsible for pumping protons out of the mitochondrial matrix. This process is called the electron transport chain, which generates ATP through oxidative phosphorylation. NADH and FADH2 are electron carriers that feed electrons into the electron transport chain, but they do not directly pump protons out of the matrix. Cytochrome c and ubiquinone are also electron carriers within the electron transport chain, but they do not directly pump protons out of the matrix either. Therefore, the correct answer is D, which includes all of the protein complexes that are directly responsible for pumping protons.

Question 14

What are the functions of cytochrome c and ubiquinone? ​

Accepted Answer

Cytochrome c and ubiquinone both act as electron carriers, shuttling electrons between the protein complexes in the electron transport chain.

Question 15

Free radicals, highly reactive species with unpaired electrons that damage molecules and cells, and can contribute to aging. Coenzyme Q (also known as ubiquinone or CoQ)is often found in lotions and moisturizers. Given what you know about the role of CoQ in cellular respiration, why would it be added to these products? ​

Accepted Answer

Coenzyme Q has antioxidant properties and can act as a free radical scavenger, helping to protect cells from damage. Therefore, it would be added to lotions and moisturizers to absorb free radicals that can cause damage to skin cells.

Question 16

Patients with pyruvate dehydrogenase complex deficiency develop neurological symptoms. Patients with this disease fail to make the substrates required for which metabolic process? ​

Accepted Answer

The answer of Patients with pyruvate dehydrogenase complex deficiency develop...

Question 17

Glycolysis, pyruvate oxidation, and the citric acid cycle all produce ____. ​

Accepted Answer

The answer of Glycolysis, pyruvate oxidation, and the citric acid...

Question 18

Compared to the mitochondrial intermembrane space, the mitochondrial matrix could be described as having ____ pH and _____ pyruvate concentration. ​

Accepted Answer

The mitochondrial matrix has a higher pH (more alkaline) and a lower pyruvate concentration compared to the intermembrane space. The intermembrane space has a lower pH due to the accumulation of protons from the electron transport chain, and a higher concentration of pyruvate due to its transport from the cytosol into the matrix.

Question 19

The final step of the citric acid cycle oxidizes malate to oxaloacetate and reduces NAD⁺. What is the purpose of this step?

Accepted Answer

The purpose of the final step of the citric acid cycle is to regenerate oxaloacetate so that it can combine with another acetyl CoA molecule to restart the cycle. This step does not produce ATP by substrate-level or oxidative phosphorylation, nor does it replenish the supplies of NAD+ and FADH2, which are continuously recycled throughout the cycle.

Question 20

During which stages of cellular respiration is CO₂ released?

Accepted Answer

CO2 is released during both pyruvate oxidation (as pyruvate is converted into acetyl-CoA) and the citric acid cycle (also known as the Krebs cycle), where carbon atoms are released as CO2 in the process of energy production.

Quiz 7: Cellular Respiration: Harvesting Chemical Energy

Which molecule is the final electron acceptor in respiration?

Ultimately, the carbon molecules in pyruvate end up in which molecule?

Which of these molecules has the most potential energy?

Citrate synthase, the first enzyme in the citric acid cycle, is regulated by ATP concentrations. Why is early regulation of ATP production the most beneficial method for the cell?

For every glucose molecule that goes through cellular respiration, how many carbon atoms are fully oxidized to CO₂ in the citric acid cycle?

A toxic substance has been found to inhibit glucose transport into mammalian cells. If this substance is administered to a hamster, the likely cause of death would be a lack of ____ production.

What is the fate of CoA after it delivers an acetyl group into the citric acid cycle?

What is the function of NADH and FADH₂?

Which molecule(s) is/are responsible for delivering the high energy electrons from the citric acid cycle to the electron transfer system?

Per molecule of glucose, oxidation occurs ____ times during the conversion of pyruvate to acetyl CoA.

The enzyme succinate dehydrogenase, located in the inner mitochondrial membrane, is directly involved in ____.

Which molecule is responsible for carrying the acetyl group from pyruvate into the citric acid cycle?

What is directly responsible for pumping protons out of the mitochondrial matrix?

What are the functions of cytochrome c and ubiquinone?

Patients with pyruvate dehydrogenase complex deficiency develop neurological symptoms. Patients with this disease fail to make the substrates required for which metabolic process?

Glycolysis, pyruvate oxidation, and the citric acid cycle all produce ____.

Compared to the mitochondrial intermembrane space, the mitochondrial matrix could be described as having pH and _ pyruvate concentration.

The final step of the citric acid cycle oxidizes malate to oxaloacetate and reduces NAD⁺. What is the purpose of this step?

During which stages of cellular respiration is CO₂ released?

Quiz 7: Cellular Respiration: Harvesting Chemical Energy

Which molecule is the final electron acceptor in respiration? ​

Ultimately, the carbon molecules in pyruvate end up in which molecule? ​

Which of these molecules has the most potential energy? ​

Citrate synthase, the first enzyme in the citric acid cycle, is regulated by ATP concentrations. Why is early regulation of ATP production the most beneficial method for the cell? ​

For every glucose molecule that goes through cellular respiration, how many carbon atoms are fully oxidized to CO2 in the citric acid cycle? ​

A toxic substance has been found to inhibit glucose transport into mammalian cells. If this substance is administered to a hamster, the likely cause of death would be a lack of ____ production. ​

What is the fate of CoA after it delivers an acetyl group into the citric acid cycle? ​

What is the function of NADH and FADH2? ​

Which molecule(s) is/are responsible for delivering the high energy electrons from the citric acid cycle to the electron transfer system? ​

Per molecule of glucose, oxidation occurs ____ times during the conversion of pyruvate to acetyl CoA. ​

The enzyme succinate dehydrogenase, located in the inner mitochondrial membrane, is directly involved in ____. ​

Which molecule is responsible for carrying the acetyl group from pyruvate into the citric acid cycle? ​

What is directly responsible for pumping protons out of the mitochondrial matrix? ​

What are the functions of cytochrome c and ubiquinone? ​

Patients with pyruvate dehydrogenase complex deficiency develop neurological symptoms. Patients with this disease fail to make the substrates required for which metabolic process? ​

Glycolysis, pyruvate oxidation, and the citric acid cycle all produce ____. ​

Compared to the mitochondrial intermembrane space, the mitochondrial matrix could be described as having ____ pH and _____ pyruvate concentration. ​

The final step of the citric acid cycle oxidizes malate to oxaloacetate and reduces NAD+. What is the purpose of this step? ​

During which stages of cellular respiration is CO2 released? ​

Which molecule is the final electron acceptor in respiration?

Ultimately, the carbon molecules in pyruvate end up in which molecule?

Which of these molecules has the most potential energy?

Citrate synthase, the first enzyme in the citric acid cycle, is regulated by ATP concentrations. Why is early regulation of ATP production the most beneficial method for the cell?

For every glucose molecule that goes through cellular respiration, how many carbon atoms are fully oxidized to CO₂ in the citric acid cycle?

A toxic substance has been found to inhibit glucose transport into mammalian cells. If this substance is administered to a hamster, the likely cause of death would be a lack of ____ production.

What is the fate of CoA after it delivers an acetyl group into the citric acid cycle?

What is the function of NADH and FADH₂?

Which molecule(s) is/are responsible for delivering the high energy electrons from the citric acid cycle to the electron transfer system?

Per molecule of glucose, oxidation occurs ____ times during the conversion of pyruvate to acetyl CoA.

The enzyme succinate dehydrogenase, located in the inner mitochondrial membrane, is directly involved in ____.

Which molecule is responsible for carrying the acetyl group from pyruvate into the citric acid cycle?

What is directly responsible for pumping protons out of the mitochondrial matrix?

What are the functions of cytochrome c and ubiquinone?

Patients with pyruvate dehydrogenase complex deficiency develop neurological symptoms. Patients with this disease fail to make the substrates required for which metabolic process?

Glycolysis, pyruvate oxidation, and the citric acid cycle all produce ____.

Compared to the mitochondrial intermembrane space, the mitochondrial matrix could be described as having pH and _ pyruvate concentration.

The final step of the citric acid cycle oxidizes malate to oxaloacetate and reduces NAD⁺. What is the purpose of this step?

During which stages of cellular respiration is CO₂ released?