AP Biology : Understand aerobic respiration

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Understand Aerobic Respiration

Oxygen is necessary for aerobic respiration, because __________.

Possible Answers:

it establishes the proton gradient

it is the final electron acceptor in the electron transport chain

it is necessary in order for ATP synthase to work properly

it donates its electrons to the electron transport chain

Correct answer:

it is the final electron acceptor in the electron transport chain

Explanation:

Oxygen is the final electron acceptor in aerobic respiration. It becomes water upon being reduced by the accepted electrons, which explains why water is one of the products of respiration. Without the presence of oxygen, electrons would remain trapped and bound in the final step of the electron transport chain, preventing further reaction.

NADH and FADH2 are necessary to donate electrons to the electron transport chain.

Example Question #2 : Understand Aerobic Respiration

Which of the following chemical equations represents the net chemical reaction of aerobic cellular respiration?

Possible Answers:

None of these

Correct answer:

Explanation:

Aerobic cellular respiration is the process of breaking down glucose  to form intermittent electron electron carriers, which eventually donate their electrons to the final electron acceptor, oxygen, at the end of the electron transport chain. This process produces usable energy in the form of ATP, as well as waste produced of carbon dioxide and water.

Example Question #3 : Understand Aerobic Respiration

Eukaryotes are capable of producing ATP with or without oxygen. In comparison, prokaryotes __________.

Possible Answers:

None of these; it depends on the type of prokaryote.

only produce ATP when oxygen is present

are also capable of producing ATP with and without oxygen

only produce ATP when oxygen is not present

do not produce ATP

Correct answer:

None of these; it depends on the type of prokaryote.

Explanation:

One way to divide prokaryotes is into aerobes and anaerobes. Aerobes are organisms that can survive and grow in the presence of oxygen while anaerobes did not require oxygen for survival and growth. All aerobes can produce ATP with or without oxygen (though they may need oxygen for survival. However some anaerobes are harmed by the presence of oxygen (obligate anaerobes). These anaerobes can produce ATP through glycolysis or anaerobic respiration, where another molecule besides oxygen is used as the final electron acceptor for the electron transport chain.

Example Question #131 : Cellular Respiration

In the process of cellular respiration, if no oxygen is available, what is the fate of the pyruvate molecules produced during glycolysis?

Possible Answers:

Used to produce protons to increase the proton gradient

Used for lactic acid or alcoholic fermentation

Used to produce more glucose

Used to produce oxygen

Correct answer:

Used for lactic acid or alcoholic fermentation

Explanation:

If no oxygen is available, anaerobic respiration will occur. This can either be lactic acid fermentation, or alcoholic fermentation. In alcoholic or lactic acid fermentation, the pyruvate are decarboxylated and ultimately used to produce either ethanol or lactic acid, and regenerate NAD+ which will be reused for another cycle of glycolysis (2 ATP are produced for each round of glycolysis).

Example Question #132 : Cellular Respiration

Anaerobic respiration occurs when?

Possible Answers:

In the presence of 

In the absence of 

In the presence of 

In the absence of 

Correct answer:

In the absence of 

Explanation:

If no oxygen is available, anaerobic respiration will occur. This can either be lactic acid fermentation, or alcoholic fermentation. In alcoholic or lactic acid fermentation, the pyruvate are decarboxylated and ultimately used to produce either ethanol or lactic acid, and regenerate NAD+ which will be reused for another cycle of glycolysis (2 ATP are produced for each round of glycolysis).

Example Question #133 : Cellular Respiration

Where does anaerobic respiration occur in a cell?

Possible Answers:

Inner mitochondrial membrane

Cytosol

Mitochondrial matrix

Chloroplast

Correct answer:

Cytosol

Explanation:

In the absence of oxygen, pyruvate produced during glycolysis will be used for either lactic acid or alcoholic fermentation, producing lactic acid or ethanol (as waste products) and regenerating NAD+ to be used for another cycle of glycolysis. This fermentation occurs in the cytosol of the cell.

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