Chapter 9: Photosynthesis and Cellular Respiration Review

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1. In cells, the energy available in food is used to make an energy-rich compound called
ATP
2. The first step in releasing the energy of glucose in the cell is known as
Glycolysis
3. The process that releases energy from food in the presence of oxygen is
ATP Synthase
4. Which organisms perform cellular respiration
Polar Bear
5. The net gain of energy from glycolysis is
2 ATP molecules
6. Because fermentation takes place in the absence of oxygen, it is said to be
Anaerobic
7. The Krebs cycle takes place within the
mitochondrion
8. The electron transport chain uses the high-energy electrons from the Kerbs cycle to
Convert ADP to ATP
9. A total of 36 molecules of ATP are produced from 1 molecule of glucose as a result of
cellular respiration
10. During heavy exercise, the buildup of lactic acid in muscle cells results in
Oxygen Debt
12. How is glucose changed during glycolysis? What products are produced as a result of glycolysis?
During glycolysis, glucose is bro- ken down into two molecules of pyruvic acid. The other products are ATP molecules and high-energy electrons that are picked up by NAD+.
13. What are the two pathways that might follow glycolysis? What factor can determine which of those pathways a cell might follow?
After glycolysis, if oxygen is avail- able, a cell might carry out the rest of cellular respiration. If oxygen is not available, some cells carry out the rest of fermentation.
14. Use formulas to write a chemical equation for cellular respiration. Label the formulas with the names of the compounds
6O2 + C6H12O6 → 6CO2 + 6H2O + energy; oxygen + glucose → carbon dioxide + water + energy
16. How is NAD+ involved in the products of glycolysis? What happens to a cell's NAD+ when large numbers of high energy electrons are produced in a short time?
NAD+ picks up high-energy electrons produced during glycolysis, forming NADH. The large number of high- energy electrons quickly fills all of the cell's available NAD+ molecules. Without NAD+, the cell cannot keep glycolysis going, and ATP production stops.
17. Which two compounds react during fermentation? Which of these compounds passes higher energy electrons to the other?
Pyruvic acid and NADH react together as NADH passes high- energy electrons to pyruvic acid
18. Write the equations to show how lactic fermentation compares with alcoholic germentation. Which reactant(s) do they have in common?
Lactic acid fermentation: glucose → lactic acid Alcoholic fermentation: glucose → alcohol CO2
Both have glucose as the reactant.
19. How are fermentation and cellular respiration similar? What is the main difference between their starting compounds?
Fermentation and cellular respiration are both processes that break down glucose and release the energy stored in the molecule. Both start with the process of glycolysis, which produces pyruvic acid. Cellular respiration requires oxygen as a reactant. Fermentation occurs with- out oxygen.
20. Summarize what happens during the krebs cycle. What happens to the high energy electrons generated during the krebs cycle?
During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of reactions that give off energy. The high-energy electrons that are produced are picked up by a series of electron carriers, and the energy is used to convert ADP into ATP.
21. How is ATP synthase involved in making energy available to the cell?
ATP synthase is a large protein through which hydrogen ions (H) pass, converting ADP into high- energy ATP.
22. When runners race for about 20
minutes, how do their bodies obtain energy?
At the beginning of a race, runners' energy comes from ATP that is present in their muscles and that is produced by lactic acid fermentation. When runners race for about 20 minutes, their bodies use cellular respiration to use stored carbohydrates to make ATP. The body stores energy in muscle and other tissues in the form of carbohydrate glycogen.
• Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen
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• Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound
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• Glycolysis captures two pairs of high-energy electrons with the carrier NAD+. Because glycolysis does not require oxygen, it supplies chemical energy to cells when oxygen is not available
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• The two main types of fermentation are alcoholic fermentation and lactic acid fermentation
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• In the absence of oxygen, yeast and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes
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• Animals cannot perform alcoholic fermentation, but some cells, such as human muscle cells, can convert glucose into lactic acid. This is called lactic acid fermentation
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• During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions
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• The electron transport chain uses the high energy electrons from the Krebs cycle to convert ADP into ATP
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• The products of photosynthesis are similar to the reactants of cellular respiration. The Products of cellular respiration are the reactants of photosynthesis
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