0

Krebs Cycle: The Central Hub of Energy Metabolism - Exploring the Citric Acid Cycle

Description: Welcome to the quiz on the Krebs Cycle, also known as the Citric Acid Cycle! This quiz will test your understanding of this central metabolic pathway, which plays a crucial role in energy production and the metabolism of carbohydrates, fats, and proteins.
Number of Questions: 14
Created by:
Tags: krebs cycle citric acid cycle energy metabolism cellular respiration
Attempted 0/14 Correct 0 Score 0

What is the primary function of the Krebs Cycle?

  1. To generate ATP through oxidative phosphorylation

  2. To produce NADH and FADH2, which are used in the electron transport chain

  3. To convert pyruvate into acetyl-CoA

  4. All of the above


Correct Option: D
Explanation:

The Krebs Cycle performs multiple essential functions, including generating ATP, producing NADH and FADH2, and converting pyruvate into acetyl-CoA.

How many steps are involved in the Krebs Cycle?

  1. 6

  2. 8

  3. 10

  4. 12


Correct Option: B
Explanation:

The Krebs Cycle consists of a series of eight enzymatic reactions that occur in a cyclic manner.

Which molecule enters the Krebs Cycle?

  1. Glucose

  2. Pyruvate

  3. Acetyl-CoA

  4. Citrate


Correct Option: C
Explanation:

Acetyl-CoA, derived from the breakdown of carbohydrates, fats, and proteins, is the molecule that enters the Krebs Cycle.

What is the first reaction of the Krebs Cycle?

  1. Condensation of acetyl-CoA with oxaloacetate to form citrate

  2. Isomerization of citrate to isocitrate

  3. Oxidation of isocitrate to α-ketoglutarate

  4. Decarboxylation of α-ketoglutarate to succinyl-CoA


Correct Option: A
Explanation:

The first reaction of the Krebs Cycle is the condensation of acetyl-CoA with oxaloacetate to form citrate, catalyzed by the enzyme citrate synthase.

Which reaction of the Krebs Cycle produces the most ATP?

  1. Conversion of isocitrate to α-ketoglutarate

  2. Decarboxylation of α-ketoglutarate to succinyl-CoA

  3. Conversion of succinyl-CoA to succinate

  4. Oxidation of succinate to fumarate


Correct Option: B
Explanation:

The decarboxylation of α-ketoglutarate to succinyl-CoA, catalyzed by the enzyme α-ketoglutarate dehydrogenase, is the reaction that produces the most ATP in the Krebs Cycle.

What is the final product of the Krebs Cycle?

  1. Oxaloacetate

  2. Malate

  3. Fumarate

  4. Succinate


Correct Option: A
Explanation:

The final product of the Krebs Cycle is oxaloacetate, which is regenerated to start the cycle again.

How many molecules of ATP are produced per glucose molecule through the Krebs Cycle?

  1. 2

  2. 4

  3. 6

  4. 8


Correct Option: A
Explanation:

The Krebs Cycle directly produces 2 molecules of ATP per glucose molecule.

What is the role of NADH and FADH2 in the Krebs Cycle?

  1. They are electron carriers that transfer electrons to the electron transport chain

  2. They are used to generate ATP through oxidative phosphorylation

  3. They are involved in the decarboxylation reactions of the Krebs Cycle

  4. All of the above


Correct Option: D
Explanation:

NADH and FADH2 are electron carriers that transfer electrons to the electron transport chain, where ATP is generated through oxidative phosphorylation. They are also involved in the decarboxylation reactions of the Krebs Cycle.

Which enzyme catalyzes the conversion of isocitrate to α-ketoglutarate?

  1. Citrate synthase

  2. Aconitase

  3. Isocitrate dehydrogenase

  4. α-Ketoglutarate dehydrogenase


Correct Option: C
Explanation:

The conversion of isocitrate to α-ketoglutarate is catalyzed by the enzyme isocitrate dehydrogenase.

What is the name of the enzyme that catalyzes the decarboxylation of α-ketoglutarate to succinyl-CoA?

  1. Citrate synthase

  2. Aconitase

  3. Isocitrate dehydrogenase

  4. α-Ketoglutarate dehydrogenase


Correct Option: D
Explanation:

The decarboxylation of α-ketoglutarate to succinyl-CoA is catalyzed by the enzyme α-ketoglutarate dehydrogenase.

Which reaction of the Krebs Cycle involves the transfer of a high-energy phosphate group to GDP to form GTP?

  1. Conversion of isocitrate to α-ketoglutarate

  2. Decarboxylation of α-ketoglutarate to succinyl-CoA

  3. Conversion of succinyl-CoA to succinate

  4. Oxidation of succinate to fumarate


Correct Option: C
Explanation:

The conversion of succinyl-CoA to succinate, catalyzed by the enzyme succinyl-CoA synthetase, involves the transfer of a high-energy phosphate group to GDP to form GTP.

What is the name of the enzyme that catalyzes the oxidation of succinate to fumarate?

  1. Succinate dehydrogenase

  2. Fumarase

  3. Malate dehydrogenase

  4. Citrate synthase


Correct Option: A
Explanation:

The oxidation of succinate to fumarate is catalyzed by the enzyme succinate dehydrogenase.

Which reaction of the Krebs Cycle involves the addition of water to fumarate to form malate?

  1. Conversion of isocitrate to α-ketoglutarate

  2. Decarboxylation of α-ketoglutarate to succinyl-CoA

  3. Conversion of succinyl-CoA to succinate

  4. Oxidation of succinate to fumarate


Correct Option: D
Explanation:

The addition of water to fumarate to form malate is catalyzed by the enzyme fumarase.

What is the name of the enzyme that catalyzes the oxidation of malate to oxaloacetate?

  1. Succinate dehydrogenase

  2. Fumarase

  3. Malate dehydrogenase

  4. Citrate synthase


Correct Option: C
Explanation:

The oxidation of malate to oxaloacetate is catalyzed by the enzyme malate dehydrogenase.

- Hide questions