Question 26: Answer each of the following questions clearly and concisely.
1. Compare and discuss how cells store energy and release energy using ATP. Be specific!

2. Compare lactic acid fermentation and alcoholic fermentation by describing what pyruvic acid is changed into. Be sure to include what type of organism each one takes place in.

What is pyruvic acid changed into? Organism:
Alcoholic Fermentation

Lactic Acid Fermentation

3. Name the three processes of aerobic cellular respiration. What is the total ATP produced from one glucose?

3 Processes of Cellular Respiration:

4. Name the two stages of photosynthesis and list the starting molecule(s) and ending molecule(s) of each.

Stages Starting Molecule(s) Product(s)

5. What is the general chemical equation of photosynthesis?

6. When and why does our body use lactic acid fermentation?

7. Explain how the equations for photosynthesis and cellular respiration compare.

Question 27:
Critical Reading
Read these passages from the text and answer the questions that follow.
Fermentation
An important way of making ATP without oxygen is called fermentation. It involves glycolysis but not the other two stages of aerobic respiration. Many bacteria and yeasts carry out fermentation. People use these organisms to make yogurt, bread, wine, and biofuels. Human muscle cells also use fermentation. This occurs when muscle cells cannot get oxygen fast enough to meet their energy needs through aerobic respiration. There are two types of fermentation: lactic acid fermentation and alcoholic fermentation. Both types are described below.
Lactic Acid Fermentation
In lactic acid fermentation, pyruvic acid from glycolysis changes to lactic acid. In the process, NAD+ forms from NADH. NAD+, in turn, lets glycolysis continue. This results in additional molecules of ATP. This type of fermentation is carried out by the bacteria in yogurt. It is also used by your muscle cells when you work them hard and fast.
Did you ever run a race and notice that your muscles feel tired and sore afterward? This is because your muscle cells use lactic acid fermentation for energy. This causes lactic acid to build up in the muscles. It is the buildup of lactic acid that makes the muscles feel tired and sore.

Alcoholic Fermentation
In alcoholic fermentation, pyruvic acid changes to alcohol and carbon dioxide. NAD+ also forms from NADH, allowing glycolysis to continue making ATP. This type of fermentation is carried out by yeasts and some bacteria. It is used to make bread, wine, and biofuels.

Alcoholic fermentation produces ethanol and NAD+. The NAD+ allows glycolysis to continue making ATP.
Have your parents ever put corn in the gas tank of their car? They did if they used gas-containing ethanol. Ethanol is produced by the alcoholic fermentation of glucose in corn or other plants. This type of fermentation also explains why bread dough rises. Yeasts in bread dough use alcoholic fermentation and produce carbon dioxide gas. The gas forms bubbles in the dough, which causes the dough to expand. The bubbles also leave small holes in the bread after it bakes, making the bread light and fluffy.

Questions
1. What is fermentation?

2. Why is NAD+ so important in fermentation?

3. Both lactic acid fermentation and alcoholic fermentation begin with the same molecule. What is that molecule and where did it come from?

4. Why is bread light and fluffy?

5. Why do your muscles get sore after intense activity?