What Do You Know About Glycolysis Metabolic Pathway? Trivia Quiz

1. NAD+ is a __________, its reduced form is _____________.

Electron carrier, NADPH

Electron carrier, NADH

Reducing agent, NAD

Transport protein, NADH

NAD+ is a molecule that functions as an electron carrier in cellular respiration. It accepts electrons from other molecules and becomes reduced to NADH. NADH can then donate these electrons to the electron transport chain, where they are used to generate ATP. Therefore, NAD+ is correctly identified as an electron carrier, and its reduced form is correctly identified as NADH.

Explanation

NAD+ is a molecule that functions as an electron carrier in cellular respiration. It accepts electrons from other molecules and becomes reduced to NADH. NADH can then donate these electrons to the electron transport chain, where they are used to generate ATP. Therefore, NAD+ is correctly identified as an electron carrier, and its reduced form is correctly identified as NADH.

2. How many molecules of carbon dioxide are generated for each molecule of acetyl CoA introduced into the citric acid cycle?

1

2

3

4

For each molecule of acetyl CoA introduced into the citric acid cycle, two molecules of carbon dioxide are generated. This is because during the citric acid cycle, the acetyl CoA is oxidized and broken down, resulting in the release of two molecules of carbon dioxide as a byproduct. Therefore, the correct answer is 2.

Explanation

For each molecule of acetyl CoA introduced into the citric acid cycle, two molecules of carbon dioxide are generated. This is because during the citric acid cycle, the acetyl CoA is oxidized and broken down, resulting in the release of two molecules of carbon dioxide as a byproduct. Therefore, the correct answer is 2.

3. What are the inputs and ouputs of the citric acid cycle?

Inputs: glucose, oxygen; outputs: carbon dioxide, ATP

Inputs: acetyl CoA, NAD, FAD, ADP; outputs: carbon dioxide, NADH, FADH2, ATP

Inputs: glucose, ATP, NAD, ADP; outputs: pyruvate, ATP, NADH, water

Inputs: pyruvate, NAD, FAD, ADP; outputs: carbon dioxide, NADH, FADH2, ATP

The citric acid cycle, also known as the Krebs cycle, is a series of chemical reactions that occur in the mitochondria of cells. It is an important part of cellular respiration and plays a key role in the production of ATP, the main energy currency of cells.

The correct answer states that the inputs of the citric acid cycle are acetyl CoA, NAD, FAD, and ADP. Acetyl CoA is derived from the breakdown of glucose or other molecules, while NAD and FAD are coenzymes that carry electrons. ADP is a precursor molecule that is used to produce ATP.

The outputs of the citric acid cycle are carbon dioxide, NADH, FADH2, and ATP. Carbon dioxide is a waste product that is released into the bloodstream and eventually exhaled. NADH and FADH2 are high-energy molecules that carry electrons to the electron transport chain, where they are used to generate more ATP. Finally, ATP is the end product of the citric acid cycle and is used by cells as a source of energy.

Explanation

The citric acid cycle, also known as the Krebs cycle, is a series of chemical reactions that occur in the mitochondria of cells. It is an important part of cellular respiration and plays a key role in the production of ATP, the main energy currency of cells.

The correct answer states that the inputs of the citric acid cycle are acetyl CoA, NAD, FAD, and ADP. Acetyl CoA is derived from the breakdown of glucose or other molecules, while NAD and FAD are coenzymes that carry electrons. ADP is a precursor molecule that is used to produce ATP.

The outputs of the citric acid cycle are carbon dioxide, NADH, FADH2, and ATP. Carbon dioxide is a waste product that is released into the bloodstream and eventually exhaled. NADH and FADH2 are high-energy molecules that carry electrons to the electron transport chain, where they are used to generate more ATP. Finally, ATP is the end product of the citric acid cycle and is used by cells as a source of energy.

4. In the conversion of glucose and oxygen to carbon dioxide and water, which molecule is oxidized?

Oxygen

Carbon dioxide

Glucose

Water

Glucose is oxidized in the conversion of glucose and oxygen to carbon dioxide and water. This is because oxidation involves the loss of electrons, and glucose loses electrons during this process. Oxygen, on the other hand, acts as the oxidizing agent and accepts the electrons from glucose, but it is not itself being oxidized.

Explanation

Glucose is oxidized in the conversion of glucose and oxygen to carbon dioxide and water. This is because oxidation involves the loss of electrons, and glucose loses electrons during this process. Oxygen, on the other hand, acts as the oxidizing agent and accepts the electrons from glucose, but it is not itself being oxidized.

5. Why is glycolysis considered one of the first metabolic pathways to have evolved?

It relies on fermentation, which is characteristic of archaea & bacteria

It is found only in prokaryotes, whereas eukaryotes use their mitochondria to produce ATP

It produces much less ATP than does the electron transport chain & chemiosmosis

It relies totally on enzymes that are produced by free ribosomes, and bacteria have only free ribosomes and no bound ribosomes

It is nearly universal, is located in the cytosol, and does not involve oxygen

Glycolysis is considered one of the first metabolic pathways to have evolved primarily because it is nearly universal, occurring in virtually all living organisms, and it does not require oxygen. These characteristics suggest that glycolysis likely evolved in an ancient, oxygen-lacking environment, possibly before the atmosphere contained significant amounts of oxygen. Additionally, glycolysis occurs in the cytosol, the fluid component of the cell, making it accessible to simple cells without specialized organelles like mitochondria. This universality and simplicity make glycolysis a fundamental and ancient metabolic pathway.

Explanation

Glycolysis is considered one of the first metabolic pathways to have evolved primarily because it is nearly universal, occurring in virtually all living organisms, and it does not require oxygen. These characteristics suggest that glycolysis likely evolved in an ancient, oxygen-lacking environment, possibly before the atmosphere contained significant amounts of oxygen. Additionally, glycolysis occurs in the cytosol, the fluid component of the cell, making it accessible to simple cells without specialized organelles like mitochondria. This universality and simplicity make glycolysis a fundamental and ancient metabolic pathway.

6. Cyanide is a poison that blocks the passage of electrons along the ETC. Which of the following is a metabolic effect of this poison?

No proton gradient would be produced, and ATP synthesis would cease

NADH supplies would be exhausted, and ATP synthesis would cease

Alcohol would build up in the cells

Electrons are passed directly to oxygen, causing cells to explode

The pH of the intermembrane space becomes much lower than normal

Cyanide is a poison that blocks the passage of electrons along the Electron Transport Chain (ETC). The ETC is responsible for creating a proton gradient across the inner mitochondrial membrane, which is necessary for ATP synthesis. Therefore, if cyanide blocks the ETC, no proton gradient would be produced, leading to the cessation of ATP synthesis. This explains why no proton gradient would be produced, and ATP synthesis would cease as a metabolic effect of cyanide poisoning.

Explanation

Cyanide is a poison that blocks the passage of electrons along the Electron Transport Chain (ETC). The ETC is responsible for creating a proton gradient across the inner mitochondrial membrane, which is necessary for ATP synthesis. Therefore, if cyanide blocks the ETC, no proton gradient would be produced, leading to the cessation of ATP synthesis. This explains why no proton gradient would be produced, and ATP synthesis would cease as a metabolic effect of cyanide poisoning.

7. In addition to 2 net ATP and carbon dioxide, infermentation either ______ or ______ are produced.

Pyruvate or alcohol

Acetyl CoA or lactic acid

Lactic acid or alcohol

Pyruvate or NADH

In fermentation, pyruvate is converted into either lactic acid or alcohol. This process occurs in the absence of oxygen and is an alternative pathway for energy production. Lactic acid fermentation occurs in certain bacteria and muscle cells, while alcohol fermentation is common in yeast and some bacteria. Both pathways regenerate NAD+ from NADH, allowing glycolysis to continue producing ATP. Therefore, the correct answer is lactic acid or alcohol.

Explanation

In fermentation, pyruvate is converted into either lactic acid or alcohol. This process occurs in the absence of oxygen and is an alternative pathway for energy production. Lactic acid fermentation occurs in certain bacteria and muscle cells, while alcohol fermentation is common in yeast and some bacteria. Both pathways regenerate NAD+ from NADH, allowing glycolysis to continue producing ATP. Therefore, the correct answer is lactic acid or alcohol.

8. Account for the net production of ATP at each step of cell respiration for one molecule of glucose.

Glycolysis=2, citric acid cycle=2, oxidative phosphorylation=32

Glycolysis=4, citric acid cycle=2, oxidative phosphorylation=32

Glycolysis=2, citric acid cycle=1, oxidative phosphorylation=32

Glycolysis=2, citric acid cycle=2, oxidative phosphorylation=36

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Explanation

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9. What is the role of oxygen in cellular respiration?

It is reduced in glycolysis as glucose is oxidized

It provides electrons to the ETC

It provides the activation energy needed for oxidation to occur

It is the final electron acceptor for the ETC

It combines with the carbon removed during the citric acid cycle to form carbon dioxide

Oxygen serves as the final electron acceptor for the electron transport chain (ETC) in cellular respiration. During the ETC, electrons are passed along a series of proteins, and oxygen accepts these electrons at the end of the chain, forming water. This process is crucial for the production of ATP, the energy currency of the cell. Without oxygen as the final electron acceptor, the ETC would not be able to function properly, leading to a decrease in ATP production and potentially disrupting cellular respiration.

Explanation

Oxygen serves as the final electron acceptor for the electron transport chain (ETC) in cellular respiration. During the ETC, electrons are passed along a series of proteins, and oxygen accepts these electrons at the end of the chain, forming water. This process is crucial for the production of ATP, the energy currency of the cell. Without oxygen as the final electron acceptor, the ETC would not be able to function properly, leading to a decrease in ATP production and potentially disrupting cellular respiration.

10. Which of the following reactions is incorrectly paired with its location?

ATP synthysis-inner membrane of the mitochondrion, matrix, and cytosol

Fermentation - cell cytosol

Glycolysis - cell cytosol

Substrate level phosphorylation - cytosol & matrix

Citric acid cycle - cristae of mitochondrion

The citric acid cycle, also known as the Krebs cycle, takes place in the matrix of the mitochondrion, not in the cristae. The cristae of the mitochondrion are involved in the electron transport chain, which is a separate process that occurs after the citric acid cycle. Therefore, the pairing of the citric acid cycle with the cristae of the mitochondrion is incorrect.

Explanation

The citric acid cycle, also known as the Krebs cycle, takes place in the matrix of the mitochondrion, not in the cristae. The cristae of the mitochondrion are involved in the electron transport chain, which is a separate process that occurs after the citric acid cycle. Therefore, the pairing of the citric acid cycle with the cristae of the mitochondrion is incorrect.