Glycolysis Questions

1. Early in glycolysis, a glucose molecule is split into which of the following?

(A) Two pyruvate molecules
(B) Four ATP
(C) Two NADH
(D) Two three-carbon sugar molecules
(E) Water and oxygen

2. What is the net gain of ATP from glycolysis?

(A) One molecule
(B) Two molecules
(C) Three molecules
(D) Four molecules
(E) Five molecules

3. Glycolysis takes place in the

(A) mitochondria.
(B) endoplasmic reticulum.
(C) nucleus.
(D) cell membrane.
(E) cytoplasm.

4. In glycolysis, which compounds are oxidized and which are reduced?

(A) Two three-carbon sugars are oxidized, and two NAD⁺ are reduced.
(B) Two three-carbon sugars, and two NAD⁺ are oxidized.
(C) Glucose is reduced, and nothing is oxidized.
(D) Two NAD⁺ are reduced, and two three-carbon sugars are oxidized.
(E) Two NAD⁺, and two three-carbon sugars are reduced.

5. Which of these statements is true?

(A) Glycolysis results in an energy loss.
(B) Glycolysis results in an energy gain.
(C) At the end of glycolysis, glucose is ready to move into the citric acid cycle.
(D) No redox reactions take place during glycolysis.
(E) Glycolysis occurs only when oxygen is present.

Citric Acid Cycle Questions

1. Which compound enters the citric acid cycle?

(A) Glucose
(B) Pyruvate
(C) Acetyl-CoA
(D) NAD⁺
(E) FAD

2. The transition step and the citric acid cycle produce which gas?

(A) Oxygen
(B) Carbon dioxide
(C) Methane
(D) Neon
(E) Nitrogen

3. If only one ATP molecule is made with each turn of the citric acid cycle, where does most of the energy from pyruvate go?

(A) There is no leftover energy because it was all converted to ATP.
(B) It was given off as carbon dioxide.
(C) The energy is needed to replenish the oxaloacetate at the end of the citric acid cycle.
(D) The energy is used to transfer electrons from NADH to NAD⁺.
(E) The energy remains in NADH and FADH₂, at least until the next step of cellular respiration.

4. Which molecule is necessary for the citric acid cycle to run?

(A) Glucose
(B) Hydrogen
(C) Nitrogen
(D) Oxygen
(E) Carbon dioxide

5. Which statement is true about the citric acid cycle?

(A) Oxidation of carbon compounds causes electron transfer to NAD⁺ and FAD.
(B) Reduction of glucose results in ATP production.
(C) Oxaloacetate is reduced, and NADH is oxidized.
(D) The citric acid cycle oxidizes ATP.
(E) Redox reactions are not important to the citric acid cycle.

Oxidative Phosphorylation Questions

1. Which compound is the typical electron donor to the electron transport chain?

(A) Glucose
(B) Water
(C) Pyruvate
(D) FADH₂
(E) NADH

2. What is the final electron acceptor in the electron transport chain?

(A) Water
(B) Oxygen
(C) Carbon dioxide
(D) NAD⁺
(E) FAD

3. Most of the electron carriers in the ETC are

(A) carbohydrates.
(B) lipids.
(C) proteins.
(D) water molecules.
(E) oxygen molecules.

4. A gradient of which ion powers ATP synthase to make ATP?

(A) H⁺
(B) NAD⁺
(C) ADP
(D) FADH
(E) O₂

5. Which membrane is the location of ATP synthase?

(A) The cell membrane
(B) The nuclear membrane
(C) The outer mitochondrial membrane
(D) The inner mitochondrial membrane
(E) The ribosomal membrane

Fermentation and Anaerobic Respiration Questions

1. Fermentation is different than the citric acid cycle and oxidative phosphorylation because

(A) it can take place without oxygen.
(B) it does not use an electron transport chain.
(C) it can produce alcohol.
(D) it can produce lactic acid.
(E) All of the above.

2. Which is the oxidizing agent in fermentation?

(A) Glucose
(B) NAD⁺
(C) NADH
(D) Ethanol
(E) Lactic acid

3. Which organisms are capable of anaerobic respiration?

(A) Cats
(B) Dogs
(C) Humans
(D) Monkeys
(E) Bacteria

4. Fermentation yields which of the following products?

(A) ATP
(B) Oxygen
(C) Water
(D) Glucose
(E) All of the above

5. Which gas is let off by alcohol fermentation?

(A) Oxygen
(B) Methane
(C) Hydrogen
(D) Carbon dioxide
(E) Water vapor

Glycolysis Answers

1. The correct answer is (D).

Although pyruvate, ATP, and NADH are end products of glycolysis, the glucose molecule splits into two early in the process.

2. The correct answer is (B).

Four ATP molecules are made but two are used, so the net gain of ATP is two molecules.

3. The correct answer is (E).

The other phases of cellular respiration take place in the mitochondria.

4. The correct answer is (A).

Oxidation and reduction always happen together. Since NAD⁺ becomes NADH, it loses the +, which means it must gain an electron.

5. The correct answer is (B).

Two ATP and two NADH are gained from glycolysis.

Citric Acid Cycle Answers

1. The correct answer is (C).

Although we started with pyruvate, it was converted to acetyl-CoA in the transition, or bridge step, before entering the citric acid cycle.

2. The correct answer is (B).

Six CO₂ molecules are given off per glucose molecule.

3. The correct answer is (E).

These two compounds will donate their electrons to the electron transport chain, making a gradient of protons that will power ATP synthesis.

4. The correct answer is (D).

The citric acid cycle only runs when O₂ is present. CO₂ is given off as a product.

5. The correct answer is (A).

Acetyl-CoA joins with oxaloacetate to make a six-carbon compound, which is oxidized in the citric acid cycle.

Oxidative Phosphorylation Answers

1. The correct answer is (E).

FADH₂ does donate electrons, but more NADH molecules are made in the citric acid cycle, so it is the donor more often.

2. The correct answer is (B).

Oxygen accepts the electrons and then combines with hydrogen ions to make water.

3. The correct answer is (C).

Proteins make up the numbered complexes I-IV. Ubiquinone is the only non-protein electron carrier.

4. The correct answer is (A).

The protons that are released during electron transfer build up on the other side of the inner mitochondrial membrane.

5. The correct answer is (D).

The electron transport chain happens along the folds of the inner mitochondrial membrane, which provides space for lots and lots of ETCs.

Fermentation and Anaerobic Respiration Answers

1. The correct answer is (E).

Fermentation happens when oxygen is not present. There are two types of fermentation: one produces alcohol, and the other produces lactic acid.

2. The correct answer is (B).

NAD⁺ is reduced to NADH, which makes it the oxidizing agent.

3. The correct answer is (E).

Microorganisms that live in environments with little or no oxygen undergo anaerobic respiration.

4. The correct answer is (A).

Fermentation makes lactic acid or ethanol as waste products.

5. The correct answer is (D).

CO₂ is let off by alcohol fermentation, but not lactic acid fermentation.