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Respiration and photosynthesis
8 MDCAT Biology questions with answers and explanations.
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Where does glycolysis take place in a cell?
- 1 Mitochondrial matrix
- 2 Cytoplasm
- 3 Nucleus
- 4 Inner mitochondrial membrane
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Correct answer: Cytoplasm
Glycolysis happens in the cytoplasm and does not need oxygen. It splits glucose into two molecules of pyruvate.
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What is the net gain of ATP from glycolysis of one glucose molecule?
- 1 2
- 2 4
- 3 36
- 4 38
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Correct answer: 2
Glycolysis uses 2 ATP and makes 4, so the net gain is 2 ATP.
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What is the final electron acceptor in aerobic respiration?
- 1 Carbon dioxide
- 2 NAD+
- 3 Oxygen
- 4 Water
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Correct answer: Oxygen
Oxygen accepts the electrons at the end of the electron transport chain and is reduced to water.
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The Krebs cycle takes place in the:
- 1 Cytoplasm
- 2 Mitochondrial matrix
- 3 Outer mitochondrial membrane
- 4 Golgi apparatus
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Correct answer: Mitochondrial matrix
The enzymes of the Krebs cycle are in the fluid matrix inside the mitochondrion.
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Alcoholic fermentation in yeast produces:
- 1 Lactic acid only
- 2 Ethanol and carbon dioxide
- 3 Acetic acid and water
- 4 Ethanol and oxygen
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Correct answer: Ethanol and carbon dioxide
Pyruvate is converted to ethanal, and then to ethanol. Carbon dioxide is released in the first step.
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The oxygen released during photosynthesis comes from:
- 1 Carbon dioxide
- 2 Glucose
- 3 Water
- 4 Chlorophyll
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Correct answer: Water
Water is split by light in photolysis. This was shown by experiments with heavy oxygen.
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Which products of the light reactions are used to run the Calvin cycle?
- 1 ATP and NADPH
- 2 Glucose and oxygen
- 3 ADP and NADP+
- 4 Pyruvate and NADH
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Correct answer: ATP and NADPH
The light reactions make ATP and NADPH, which supply the energy and reducing power for fixing carbon dioxide.
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How many carbon atoms does a molecule of pyruvate have?
- 1 2
- 2 3
- 3 4
- 4 6
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Correct answer: 3
Glucose has six carbons, and glycolysis splits it into two three-carbon molecules of pyruvate.