Cellular Respiration and Fermentation Quiz

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Questions and Answers

What characterizes a reduction in redox reactions?

An atom or molecule gains electron(s). (correct)

Only protons (H+) are transferred.

The reaction involves no electron transfer.

An atom or molecule loses electron(s).

What is an important feature of adenosine triphosphate (ATP)?

It loses phosphate groups without releasing energy.

It serves as a storage molecule for DNA.

It acts as the cellular currency for energy. (correct)

It contains only one phosphate group.

Which statement about oxidized molecules is correct?

They gain electrons and have higher potential energy.

They lose protons and have lower potential energy. (correct)

They gain protons and have lower potential energy.

They undergo a process that results in more C-H bonds.

What occurs during the cleavage of the outermost phosphate group in ATP?

ADP and inorganic phosphate (Pi) are formed while releasing energy. Signup and view all the answers

How can one determine if reduction has occurred during a redox reaction?

By observing an increase in C-H bonds. Signup and view all the answers

Which of the following is true regarding redox reactions?

Electrons may shift positions within covalent bonds. Signup and view all the answers

What is the result of the highly exergonic reaction of ATP hydrolysis?

It generates energy used for muscle contraction. Signup and view all the answers

What role do electron donors play in redox reactions?

They are oxidized and provide electrons. Signup and view all the answers

What is the primary outcome of glycolysis?

Conversion of glucose into two molecules of pyruvate Signup and view all the answers

What occurs during the Energy Investment Phase of glycolysis?

Glucose is phosphorylated using 2 ATP molecules Signup and view all the answers

What type of phosphorylation is involved in ATP production during glycolysis?

Substrate-level phosphorylation Signup and view all the answers

How many net ATP molecules are produced from glycolysis?

2 ATP Signup and view all the answers

What happens to NAD+ during glycolysis?

It is reduced to NADH Signup and view all the answers

Which of the following statements is true regarding glycolysis?

It occurs in the cytoplasm Signup and view all the answers

What are G3P molecules produced from in the first phase of glycolysis?

Phosphorylation of glucose Signup and view all the answers

Which of the following best describes substrate-level phosphorylation?

ATP is produced by transferring a phosphate group from a substrate to ADP Signup and view all the answers

What are the primary outputs of each glucose molecule in the Citric Acid Cycle?

6 CO2, 10 NADH, 2 FADH2, and 4 ATP Signup and view all the answers

Which substrate-level phosphorylation process occurs in lactic acid fermentation?

Transfer of a phosphate group from a substrate molecule to ADP Signup and view all the answers

During the Citric Acid Cycle, what happens to most of glucose's original energy?

It remains mostly in NADH and FADH2 for ATP production. Signup and view all the answers

What does the Electron Transport Chain primarily do?

It flows protons to generate a proton gradient through redox reactions. Signup and view all the answers

If a radioactive sugar is fed to a mouse, which metabolic pathway does the radioactivity follow?

Sugar to pyruvate to Citric Acid Cycle to CO2 Signup and view all the answers

What is required to generate ATP through oxidative phosphorylation?

A proton gradient established by electron transport. Signup and view all the answers

Where does lactic acid fermentation primarily occur in muscle cells?

In the cytoplasm. Signup and view all the answers

Which statement accurately describes the reduction of NAD+ during cellular respiration?

NAD+ is reduced in both glycolysis and the Citric Acid Cycle. Signup and view all the answers

What is a likely reason for the absence of detectable alcohol when sugar has been metabolized?

They did not grow the culture in anaerobic conditions Signup and view all the answers

Which stage of cellular respiration directly produces ATP through substrate-level phosphorylation?

Citric acid cycle Signup and view all the answers

In what conditions do cells use fermentation to produce ATP?

In the absence of oxygen Signup and view all the answers

What is the main disadvantage of using fermentation over cellular respiration?

Fermentation produces less ATP Signup and view all the answers

Which of the following statements best describes aerobic cellular respiration?

It requires oxygen for the complete oxidation of glucose Signup and view all the answers

What role do enzymes play in biological chemical reactions?

They typically catalyze one specific reaction. Signup and view all the answers

What happens to oxygen atoms during cellular respiration?

They are reduced to form water. Signup and view all the answers

What is the first step in cellular respiration?

Glycolysis. Signup and view all the answers

Which process involves glucose being broken down to pyruvate?

Glycolysis. Signup and view all the answers

Which reaction must occur in an electron transport chain during photosynthesis?

Reduction. Signup and view all the answers

What is the total maximum ATP yield from one molecule of glucose during cellular respiration?

29 ATP. Signup and view all the answers

What does the active site of an enzyme do?

Binds the substrate through weak interactions. Signup and view all the answers

Which of the following statements about glucose is true?

Glucose is preferred by most organisms for energy production. Signup and view all the answers

Study Notes

Redox Reactions

Redox reactions involve electron transfer and are coupled processes of reduction and oxidation.
Reduction: an atom/molecule gains electrons; oxidation: an atom/molecule loses electrons.
Electron donors are paired with electron acceptors during redox reactions.
Electrons may shift positions in covalent bonds or be completely transferred from one atom to another.

Adenosine Triphosphate (ATP)

ATP serves as the cellular energy currency and fuels most cellular activities.
ATP possesses high potential energy due to its four negative charges concentrated in a small area.
The cleaving of the terminal phosphate group from ATP produces ADP and inorganic phosphate (Pi), releasing energy for cellular work.

Enzymes

Enzymes are protein catalysts that facilitate specific reactions.
They significantly increase the rate of biological reactions by bringing substrates together in an optimal orientation.
The active site of the enzyme binds to the substrate through weak interactions.

Glucose as Energy Source

Glucose is the preferred energy source for most organisms and is metabolized to produce ATP.
It can be processed through cellular respiration or fermentation.

Cellular Respiration Overview

In cellular respiration, glucose carbon atoms are oxidized to carbon dioxide, and oxygen atoms are reduced to water.
The process consists of four main stages:
- Glycolysis: glucose converted into pyruvate.
- Pyruvate processing: pyruvate oxidized into acetyl CoA.
- Citric acid cycle: acetyl CoA oxidized to carbon dioxide.
- Electron transport and oxidative phosphorylation: ATP is produced from the oxidation of reduced compounds.

Glycolysis

Glycolysis consists of 10 reactions occurring in the cytoplasm, breaking glucose into two pyruvate molecules.
No oxygen is required for glycolysis.
Two phases:
- Energy Investment Phase: utilizes 2 ATP to phosphorylate glucose.
- Energy Payoff Phase: produces 2 pyruvate, reduces 2 NAD+ to NADH, and generates 4 ATP (net gain of 2 ATP).

Substrate-Level Phosphorylation

ATP is generated through the enzyme-catalyzed transfer of a phosphate group from a substrate to ADP.
Occurs during glycolysis and the citric acid cycle.

The Citric Acid Cycle

The citric acid cycle entails the complete oxidation of glucose with one glucose molecule driving two cycles.
Each cycle produces energy carriers (NADH and FADH2) and ATP.

Oxidation of Glucose

The initial three stages of cellular respiration completely oxidize glucose.
Each glucose molecule yields 6 CO2, reduces 10 NAD+ to NADH, reduces 2 FAD to FADH2, and produces 4 ATP via substrate-level phosphorylation.
Most energy is retained in NADH and FADH2 for ATP production through oxidative phosphorylation.

The Electron Transport Chain (ETC)

The ETC oxidizes NADH and FADH2, utilizing the released energy to pump protons (H+) across the mitochondrial inner membrane, establishing a proton gradient.

Fermentation

Fermentation is utilized to produce ATP in the absence of oxygen, albeit inefficiently compared to cellular respiration.

Summary

Cellular respiration is the process cells use to produce ATP when oxygen is available and consists of:
- Glycolysis
- Pyruvate oxidation
- Citric acid cycle
- Electron Transport Chain
ATP is generated by substrate-level phosphorylation (in glycolysis and the citric acid cycle) and oxidative phosphorylation (in the ETC).
In oxygen absence, cells resort to fermentation for ATP production.

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Description

Test your knowledge on cellular respiration and fermentation, focusing on redox reactions. Understand the process of electron transfer, oxidation, and reduction in biological systems. This quiz will help reinforce your understanding of these essential biochemical processes.