Section 9-2 The Krebs Cycle and Electron Transport
On average, how many ATP molecules are produced as each pair of high-energy electrons moves down the electron transport chain?
3 ATP
How many ATP molecules are formed during cellular respiration
38
Is the following sentence true or false? Hydrogen serves as the final electron acceptor of the electron transport chain.
False, oxygen
When does the Krebs cycle begin?
It begins when the pyruvic acid molecules enter the mitochondria.
What happens to the carbon dioxide produced in breaking down pyruvic acid?
It is released into the air.
In the presence of oxygen, how is the pyruvic acid produced in glycolysis used?
It is used in the Krebs cycle.
If photosynthesis is the process that "deposits" energy in a "savings account," then what is cellular respiration?
It's the process that "withdraws" the energy.
Where does the electron transport chain get the high-energy electrons that are passed down the chain?
NADH and FADH
What is the energy of the high-energy electrons used for every time 2 high-energy electrons move down the electron transport chain?
They are used to transport hydrogen ions.
What is the energy tally from 1 molecule of pyruvic acid during the Krebs cycle?
4 NADH, 1 FADH, and 1 ATP molecule
What are three sources of ATP a human body uses at the beginning of a race?
Muscles, lactic acid fermentation, and cellular respiration.
What happens to each of the 3 carbon atoms in pyruvic acid when it is broken down?
1 carbon atom becomes part of a carbon dioxide molecule.The other two become part of acetyl-CoA.
During the energy extraction part of the Krebs cycle, how many molecules of CO2 are released?
2 molecules
At the end of glycolysis, how much of the chemical energy in glucose is still unused?
About 90% is unused.
Why are aerobic forms of exercise so beneficial for weight control?
After the first amount of energy is used, fats and other food molecules are broken down to receive more energy.
What are the final waste products of cellular respiration?
Carbon dioxide and water
A runner needs more energy for a longer race. How does the body generate the necessary ATP?
Cellular respiration
What is the electron transport chain?
It is a series of proteins in the inner membrane of the mitochondria.
What happens to pyruvic acid during the Krebs cycle?
It is broken down into carbon dioxide.
What happens to the energy of glucose that is not used to make ATP molecules?
It is released as heat.
Why is the Krebs cycle also known as the citric acid cycle
Its first product is citric acid.
When a runner needs quick energy for a short race, what source can supply enough ATP for about 90 seconds?
Lactic acid fermentation
When electrons join NAD+ and FAD during the Krebs cycle, what do they form?
NADH and FADH
Why does a sprinter have an oxygen debt to repay after the race is over?
Oxygen is the only way to help get out the lactic acid in our body.
How are photosynthesis and cellular respiration opposite in terms of oxygen?
Photosynthesis releases oxygen, when cellular respiration needs oxygen to start the process.
How are photosynthesis and cellular respiration opposite in terms of carbon dioxide?
Photosynthesis requires carbon dioxide to start, while cellular respiration releases carbon dioxide as a waste product.
What does the electron transport chain use the high-energy electrons from the Krebs cycle for?
The electrons are used to convert the ADP into ATP.
Because the final stages of cellular respiration require oxygen, they are said to be
aerobic
