Biology Chapter 4.5 Cellular Respiration Quiz

Questions and Answers

What is the function of glycolysis?

To break down glucose into two molecules of pyruvate. Additionally, 2 NADH form and 4 ATP molecules are made.

What happens to the molecules formed during glycolysis when oxygen is available?

When oxygen is available, the pyruvate and NADH are used for cellular respiration in the mitochondria.

What is meant by a 'net gain of two ATP molecules' from glycolysis?

Glycolysis makes 4 ATP molecules, but 2 ATP molecules are used to first split the glucose molecule, resulting in a net gain of 2 ATP molecules.

What is the function of the Krebs cycle?

The Krebs cycle breaks down citric acid and transfers energy to the electron transport chain. Signup and view all the answers

What is the 1st step of the Krebs cycle?

Pyruvate broken down into a two-carbon molecule and a molecule of carbon dioxide. Signup and view all the answers

What is the 2nd step of the Krebs cycle?

Coenzyme A bonds to the 2-carbon molecule made from the breakdown of pyruvate. Signup and view all the answers

What is the 3rd step of the Krebs cycle?

The two-carbon part of the intermediate molecule is added to a 4-carbon molecule to form citric acid. Signup and view all the answers

What is the 4th step of the Krebs cycle?

The citric acid molecule is broken down by an enzyme to form a 5-carbon molecule. Signup and view all the answers

What is the 5th step of the Krebs cycle?

The five-carbon molecule is broken down to form a 4-carbon molecule, NADH, and ATP. Signup and view all the answers

What is the 6th step of the Krebs cycle?

Enzymes rearrange the four-carbon molecule, releasing high-energy electrons. Signup and view all the answers

Where is the electron transport chain in cellular respiration located?

The electron transport chain takes place in and across the inner membrane of the mitochondrion. Signup and view all the answers

What is the function of the electron transport chain?

To take energy from the Krebs cycle to produce ATP. Signup and view all the answers

What is the 1st step of the electron transport chain?

Proteins inside the inner membrane take high-energy electrons from NADH and FADH2. Signup and view all the answers

What is the 2nd step of the electron transport chain?

High-energy electrons pump hydrogen ions across the inner membrane. Signup and view all the answers

What is the 3rd step of the electron transport chain?

The flow of hydrogen ions is used to make ATP via ATP synthase. Signup and view all the answers

What is the 4th step of the electron transport chain?

Oxygen picks up electrons and hydrogen ions to form water. Signup and view all the answers

Why is oxygen needed for cellular respiration?

To pick up the electrons that travel along the chain and hydrogen ions, forming CO2 and water. Signup and view all the answers

Study Notes

Glycolysis

Glycolysis breaks down glucose into two pyruvate molecules, generating 2 NADH and a gross production of 4 ATP.
In the presence of oxygen, pyruvate and NADH enter cellular respiration pathways in mitochondria.
A net gain of 2 ATP from glycolysis results from producing 4 ATP but using 2 ATP to initiate glucose splitting.

Krebs Cycle

The Krebs cycle starts by breaking down pyruvate into a 2-carbon molecule and releasing carbon dioxide, producing NADH.
Coenzyme A attaches to the 2-carbon molecule that enters the Krebs cycle.
Citric acid is formed by combining the 2-carbon molecule with a 4-carbon molecule.
The citric acid is then broken down into a 5-carbon molecule, producing NADH and releasing carbon dioxide.
The breakdown of the 5-carbon molecule yields a 4-carbon molecule, another NADH, and ATP, with more carbon dioxide released.
The cycle finishes by rearranging the 4-carbon molecule, releasing high-energy electrons and creating NADH and FADH2 while retaining the 4-carbon backbone.

Electron Transport Chain

Located in and across the inner mitochondrial membrane, the electron transport chain extracts energy from NADH and FADH2.
High-energy electrons are removed from NADH and FADH2 by proteins within the inner membrane.
The energy from electrons pumps hydrogen ions across the membrane, creating a chemiosmotic gradient.
ATP production occurs as hydrogen ions flow back through ATP synthase, generating approximately three ATP for each pair of electrons.
Oxygen serves as the final electron acceptor, combining with electrons and hydrogen ions to form water, a waste product of cellular respiration.

Role of Oxygen

Essential for cellular respiration, oxygen facilitates the acceptance of electrons and hydrogen ions, leading to the production of carbon dioxide and water as waste products.

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Description

Test your knowledge on cellular respiration with this detailed quiz focused on glycolysis and its function. Explore key concepts such as the transformation of glucose into pyruvate and the role of oxygen in the process. Perfect for biology students looking to reinforce their understanding of this essential metabolic pathway.