Home Page Textbooks Prentice Hall Biology (California) Section 9.2: The Krebs Cycle and Electron Transport

Prentice Hall Biology (California)

1st Edition

Kenneth R. Miller, Levine

ISBN: 9780132013529

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Section 9.2: The Krebs Cycle and Electron Transport

Exercise 1

Result

1 of 1

In Krebs cycle, the pyruvic acid molecules produced during glycolysis are broken down into carbon dioxide, NADH, ATP, and FADH$_{2}$. This process takes place inside the mitochondria.

Exercise 2

Result

1 of 1

The high-energy electrons from glycolysis and Krebs cycle are utilized by the electron transport chain to convert ADP into ATP. This process starts with the electron transport of the NADH and FADH, movement of the hydrogen ion, and ends with ATP production.

Exercise 3

Step 1

1 of 2

For each molecule of glucose, the process of glycolysis only makes a net gain of 2 ATP. This is less efficient because glucose is not fully oxidized to CO$_2$ as it still contains a lot of energy.

Step 2

2 of 2

In contrast, cellular respiration fully oxidizes each molecule of glucose to CO$_2$, which releases a lot more energy (36 to 38 ATP) compared to glycolysis alone. Thus, it is more efficient.

Exercise 4

Solution 1

Solution 2

Step 1

1 of 2

**Cellular respiration** is a set of metabolic reactions and processes that happen in the cells of an organism. It is an overall process that converts chemical energy from oxygen molecules into ATP.

Step 2

2 of 2

In the process of glycolysis, the net ATP production is only 2. But together with the Krebs cycle and electron transport chain release, there are about **36 molecules** of ATP per molecule of glucose that will be produced.

Result

1 of 1

During glycolysis (anaerobic), there are 2 ATP molecules that are produced. On the other hand, during cellular respiration (aerobic), there are 36 ATP molecules that are produced. The net total of ATP molecules produced in the entire breakdown of glucose is 38 ATP molecules.

Exercise 5

Step 1

1 of 3

The flow of energy in photosynthesis is actually the reverse process when compared to cellular respiration. In photosynthesis, the energy from the sun is converted and stored as chemical energy in the form of chemical bonds in carbohydrates such as glucose sugars.

Step 2

2 of 3

On the other hand, cellular respiration breaks down the chemical bonds in carbohydrates such as glucose sugars in order to release its chemical energy and transfer it to ATP, which will then be used by the cell for its everyday activities.

Step 3

3 of 3

As we can see, photosynthesis **stores** energy within the chemical bonds of carbohydrates. In contrast, cellular respiration **releases** energy by breaking down the chemical bonds of carbohydrates. In conclusion, these processes are interconnected with each other.

Exercise 6

Result

1 of 1

When water and carbon dioxide come together during photosynthesis, a glucose molecule is formed. Just like the money in a savings account, the glucose is stored in the body in the form of ATP. Whenever the body needs energy, the ATP is taken and consumed. Using the ATP is like withdrawing the money from the bank account and spending the cash.

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Section 9.2: The Krebs Cycle and Electron Transport

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