8. Respiration

Review of Aerobic Cellular Respiration

Cellular Respiration Part 3: The Electron Transport Chain and Oxidative Phosphorylation

Glucose (C6H12O6).

Pyruvate (C3H3O3–).

Water is one of the products of aerobic cellular respiration. What is the source of the oxygen atom utilized to create the water molecules?a) Carbon dioxide (CO2).b) Glucose (C6H12O6).c) Oxygen gas (O2).d) Pyruvate (C3H3O3–).

Suppose a friend says that we don’t need to worry about the rising temperatures associated with global climate change. She claims that increased temperatures will make planktonic algae grow faster and that carbon dioxide (CO2) will be removed from the atmosphere faster. According to her, this carbon will be buried at the bottom of the ocean in calcium carbonate shells. As a result, the amount of carbon dioxide in the atmosphere will decrease and global warming will decline. Comment.

Cellular Respiration ATP count | Logos Learning

 No. Energy cannot be converted to matter in biological systems, and fat is matter. 

 It is used to make water from hydrogen ions and oxygen. 

 No. The energy derived from the reduction of oxygen drives this process. 

 It is released as carbon dioxide and water. 

 No. Energy cannot be converted to matter in biological systems, and carbon dioxide and water are forms of matter. 

 No. Energy cannot be converted to matter in biological systems, and starch is a form of matter. 

Remember your thermodynamics.

Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 32 ATP from one glucose molecule. What happens to the rest of the energy in glucose?

After glucose is fully oxidized by glycolysis, pyruvate processing, and the citric acid cycle, where is most of its energy stored?

The 10 NADH and 2 FADH2 molecules.

Through the first three stages of cellular respiration only 4 ATP molecules have been produced from the initial glucose molecule. In which of the products of these stages is the potential energy to produce more ATP molecules stored?a) The 6 molecules of CO2.b) The H+ ions produced.c) The 10 NADH and 2 FADH2 molecules.d) The 4 molecules of ATP.

 No. Although ADP is converted to ATP during oxidative phosphorylation, there is a better answer. 

 No. Although oxygen functions as the terminal electron acceptor in oxidative phosphorylation, there is a better answer. 

 No. Although ATP is the energy-containing product of oxidative phosphorylation, there is a better answer. 

 None of the listed responses is correct. 

 No. All of the listed responses are involved in oxidative phosphorylation. 

 The first three listed substances are involved in oxidative phosphorylation. 

Consider what is being oxidized (and reduced) and what is being phosphorylated.

Which of the following substances is/are involved in oxidative phosphorylation?

Most of the energy in an ATP molecule is released                   .
a. during cellular respiration;
b.when the terminal phosphate group is hydrolyzed;
c. in the form of new nucleotides;
d. when it is transferred to NADH

Most CO2 from catabolism is released during
a. glycolysis.
b. the citric acid cycle.
c. lactate fermentation.
d. electron transport.

 No. Fatty acids are not products of amino acid catabolism. 

 No. Sugar molecules are not products of amino acid catabolism. 

 No. Lactate is a product of one of the fermentation pathways of pyruvate. 

No. Ethanol and CO2 are products of one of the fermentation pathways of pyruvate.

Consider what portion of an amino acid is not a carbon chain that can be oxidized by cellular respiration.

When protein molecules are used as fuel for cellular respiration, __________ are produced as waste.

 Fats are produced when cells take in more food than they need. 

 No. This is true, but it does not explain why the oxidation of fats produces more energy than sugars. 

 Fats are less soluble in water than sugars. 

 No. This is true, but it has nothing to do with energy production in respiration. 

 Fats do not form true macromolecules as sugars do. 

 Fats are closely related to lipid molecules, which are the basic building blocks of cellular membranes. 

 Fats are better electron donors to oxygen than are sugars. 

Consider what factor or factors determines the energy content of organic molecules when they are oxidized.

A gram of fat oxidized by respiration produces approximately twice as much ATP as a gram of carbohydrate. Which of the following best explains this observation?

Fermentation

Total Products for Each Stage of Aerobic Cellular Respiration

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) through the process of aerobic cellular respiration?a) 4.b) 2.c) 26-34.d) 30-38.

 The muscle cells will have more trouble making enough ATP to meet their energy requirements. 

No. It is correct that in the absence of O2 the cells will have trouble meeting their energy demands, but is this the only correct answer?

 The cells will not be able to carry out oxidative phosphorylation. 

No. Without O2 oxidative phosphorylation will stop, but is this the only correct answer?

 The cells will consume glucose at an increased rate. 

 No. To meet their energy demands using only the ATP from glycolysis, cells will have to metabolize glucose at a higher rate, but is this the only correct answer? 

 Only the first two answers are correct. 

Consider the consequences of anaerobic conditions for cells.

If muscle cells in the human body consume O2 faster than it can be supplied, which of the following is likely to result?

2.8 Aerobic Respiration

 It supplies a non-oxygen electron acceptor to cells so that the cells can respire anaerobically. 

 No. Animal cells cannot respire anaerobically. 

 It supplies oxygen so that aerobic cellular respiration can occur instead of fermentation. 

 No. Though this is correct, a more comprehensive answer exists. 

 It supplies glucose to the rapidly dividing cells of the tumor. 

 No. Although this is true, there is a more comprehensive explanation. 

 It supplies a non-oxygen electron acceptor to cells so that the cells can respire anaerobically, and it supplies oxygen so that aerobic cellular respiration can occur instead of fermentation. 

 No. Animal cells cannot respire anaerobically; they must either respire aerobically or perform fermentation. 

 It supplies oxygen so that aerobic cellular respiration can occur instead of fermentation, and it supplies glucose to the rapidly dividing cells of the tumor. 

For ATP synthesis to be as efficient as possible, what molecules are required?

When solid tumors of animals reach a certain size, the center of the tumor begins to die. To prevent this, the tumor can recruit new blood vessels. What purpose does the recruitment of blood vessels to growing tumors serve?

Glycolysis (and Exploding Sugar Demo!)

No. NADH is formed when electrons removed from glucose are used to reduce NAD+.

 No. The oxygen in water enters the mitochondrion as molecular oxygen from the atmosphere. 

 No. ATP is produced by the phosphorylation of ADP. 

 No. Oxygen gas is reduced to water in cellular respiration. 

Determine the fate of oxygen atoms in glucose in the process of cellular respiration.

In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and after a few minutes, radioactive oxygen atoms showed up in __________.

 Temperature goes up but carbon dioxide levels remain constant because heat is a by-product of cellular respiration but carbon dioxide is converted to sugar during cellular respiration. 

 No. Although temperature would go up due to heat being produced by cellular respiration, carbon dioxide is a by-product and not used by cellular respiration. 

 Neither temperature nor carbon dioxide levels change because cellular respiration is 100% efficient and because carbon dioxide produced by cellular respiration is just as rapidly consumed by cellular respiration. 

 No. The process is only about 38% efficient, with the rest of the energy lost to the environment as heat. Carbon dioxide is not consumed during cellular respiration. 

 Temperature goes down and carbon dioxide levels remain constant. This is because cellular respiration, being an endergonic reaction, requires an input of heat energy from the environment to occur and because carbon dioxide is neither produced nor consumed by cellular respiration. 

 No. Cellular respiration is an exergonic process and as organic molecules are oxidized, carbon dioxide is released. 

 Temperature goes up and the level of carbon dioxide goes down. This is because cellular respiration is an exergonic process that is only about 38% efficient; the remaining energy is lost to the environment as heat. Also, carbon dioxide is being converted to organic molecules such as fats and sugars during cellular respiration. 

 No. Though your reasoning about temperature is correct, cellular respiration does not use carbon dioxide to synthesize organic molecules. 

 Temperature and the level of carbon dioxide rise as heat and carbon dioxide are by-products of cellular respiration. 

Consider the reaction that summarizes cellular respiration and the efficiency of cellular respiration.

Which of the following statements is the best explanation of what happens to the temperature and carbon dioxide concentration during a 1-hour class period in a classroom of 300 students if the heating and air-conditioning is turned off and all doors are kept closed?

ATP Accounting

 At the end of glycolysis to oxidize pyruvate 

No. Pyruvate oxidation does not directly require O2.

 At the end of the citric acid cycle to regenerate citric acid 

No. The production of citric acid does not directly require O2.

Between glycolysis and the citric acid cycle to split a carbon from pyruvate, producing CO2

No. This does not require O2.

As a source of O2 in every reaction that produces CO2

No. The oxygen atoms in CO2 come from glucose and water, not from O2.

At the end of the electron transport chain to accept electrons and form H2O

What redox reaction involves O2 during cellular respiration?

During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes?

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General Biology