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Photosynthesis Review Questions for AP Biology

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By — McGraw-Hill Professional
Updated on Apr 25, 2014

Review the following concepts if needed:

Review Questions

Questions 1–4 refer to the following answer choices— use each answer only once.

  1. Transpiration
  2. Calvin cycle
  3. CAM photosynthesis
  4. Cyclic photophosphorylation
  5. Noncyclic photophosphorylation
  1. Plants use this process so that they can open their stomata at night and close their stomata during the day to avoid water loss during the hot days, without depleting the plant's CO2 reserves.
  2. Uses NADPH, ATP, and CO2 as the inputs to its reactions.
  3. Photosynthetic process that has ATP as its sole product. There is no oxygen and no NADPH produced from these reactions.
  4. The process by which plants lose water via evaporation through their leaves.
  5. The photosynthetic process performed by some plants in an effort to survive the hot and dry conditions of climates such as the desert is called
    1. carbon fixation.
    2. C3 photosynthesis.
    3. C4 photosynthesis.
    4. cyclic photophosphorylation.
    5. noncyclic photophosphorylation.
  6. Which of the following is the photosynthetic stage that produces oxygen?
    1. The light-dependent reactions
    2. Chemiosmosis
    3. The Calvin cycle
    4. Carbon fixation
    5. Photorespiration
  7. Which of the following reactions occur in both cellular respiration and photosynthesis?
    1. Carbon fixation
    2. Fermentation
    3. Reduction of NADP+
    4. Chemiosmosis
    5. Formation of NADH
  8. Which of the following is not a product of the light-dependent reactions of photosynthesis?
    1. O2
    2. ATP
    3. NADPH
    4. Sugar
  9. Which of the following is an advantage held by a C4 plant?
    1. More efficient light absorption
    2. More efficient photolysis
    3. More efficient carbon fixation
    4. More efficient uptake of carbon dioxide into the stomata
    5. More efficient ATP synthesis during chemiosmosis
  10. Carbon dioxide enters the plant through the
    1. Stomata
    2. Stroma
    3. Thylakoid membrane
    4. Bundle sheath cell
  11. Which of the following is the source of the oxygen released during photosynthesis?
    1. CO2
    2. H2O
    3. Rubisco
    4. PEP carboxylase
    5. Pyruvate
  12. Which of the following is an incorrect statement about the dark reactions of photo synthesis?
    1. The main inputs to the reactions are NADPH, ATP, and CO2.
    2. The main outputs of the reactions are NADP+, ADP, and sugar.
    3. More NADPH is used than ATP during the dark reactions.
    4. Carbon fixation is the first step of the process.
    5. The reactions occur in the stroma of the chloroplast.
  13. Which of the following is the source of the carbon in sugar produced during photo synthesis?
    1. CO2
    2. H2O
    3. Rubisco
    4. PEP carboxylase
    5. Pyruvate
  14. The light-dependent reactions of photosynthesis occur in the
    1. stroma.
    2. mitochondrial matrix.
    3. thylakoid membrane.
    4. cytoplasm.
    5. nucleus.

Answers and Explanations

  1. C—CAM plants open their stomata at night and close their stomata during the day to avoid water loss due to heat. The carbon dioxide taken in during the night is incorporated into organic acids and stored in vacuoles until the next day, when the stomata close and CO2 is needed for the Calvin cycle.
  2. B—The Calvin cycle uses ATP, NADPH, and CO2 to produce the desired sugar output of photosynthesis.
  3. D—Cyclic photophosphorylation occurs because the Calvin cycle uses more ATP than it does NADPH. This is a problem because the light reactions produce an equal amount of ATP and NADPH. The plant compensates for this disparity by dropping into the cyclic phase when needed to produce the ATP necessary to keep the lightindependent reactions from grinding to a halt.
  4. A—Transpiration is the process by which plants lose water through their leaves. Not much else to be said about that.
  5. C—One of the major problems encountered by plants in hot and dry conditions is of photorespiration. In hot conditions, plants close their stomata to avoid losing water to transpiration. The problem with this is that the plants run low on CO2 and fill with O2. The oxygen competes with the carbon dioxide and attaches to RuBP, leaving the plant with a lowered capacity for growth. C plants cycle CO2 from mesophyll cells to bundle sheath cells, creating a higher concentration of CO2 in that region, thus allowing rubisco to carry out the Calvin cycle without being distracted by the O2 competitor.
  6. A—The light-dependent reactions are the source of the oxygen given off by plants.
  7. D—Chemiosmosis occurs in both photosynthesis and cellular respiration. This is the process by which the formation of ATP is driven by electrochemical gradients in the cell. Hydrogen ions accumulate on one side of a membrane, creating a proton gradient that causes them to move through channels to the other side of that membrane, thus leading, with the assistance of ATP synthase, to the production of ATP.
  8. D—Sugar is a product not of the light-dependent reactions of photosynthesis but of the Calvin cycle (the dark reactions). The outputs of the light-dependent reactions are ATP, NADPH, and O2.
  9. C—C4 plants fix carbon more efficiently than do C3 plants. Please see the explanation for question 5 for a more detailed explanation of this answer.
  10. A—The stomata is the structure through which the CO2 enters a plant and the oxygen produced in the light-dependent reactions leaves the plant.
  11. B—The source of the oxygen produced during photosynthesis is the water that is split by the process of photolysis during the light-dependent reactions of photosynthesis. In this reaction, two hydrogen ions and an oxygen atom are formed from the water. The oxygen atom immediately finds and pairs up with another oxygen atom to form the oxygen product of the light-dependent reactions.
  12. C—This is a trick question. I reversed the two compounds (NADPH and ATP) in this one. More ATP than NADPH is used in the Calvin cycle. It is for this reason that cyclic photophosphorylation exists—to produce ATP to make up for this disparity.
  13. A—The carbon of CO2 is used to produce the sugar created during the Calvin cycle.
  14. C—The light-dependent reactions occur in the thylakoid membrane of the chloroplast. Remember, the thylakoid system resembles the various stacks of poker chips located within the stroma of the chloroplast. The light-independent reactions occur in the stroma of the chloroplast.
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