The Calvin cycle, the "dark reaction" or Carbon fixation reactions of photosynthesis, cannot occur at night in a living plant. Which of the following best describes why this is true? A) The stomata are incapable of opening at night, thus CO2 cannot enter the leaf B) The reactions of the Calvin cycle are dependent on light reactions for high-energy compounds C) Several enxymes necessary for Calvin cycle activity have been degraded during the day and must be replaced

The Calvin cycle, the "dark reaction" or Carbon fixation reactions of photosynthesis, cannot occur at night in a living plant. Which of the following best describes why this is true? A) The stomata are incapable of opening at night, thus CO2 cannot enter the leaf B) The reactions of the Calvin cycle are dependent on light reactions for high-energy compounds C) Several enxymes necessary for Calvin cycle activity have been degraded during the day and must be replaced

BIOLOGY:CONCEPTS+APPL.(LOOSELEAF)

10th Edition

ISBN:9781305967359

Author:STARR

Publisher:STARR

Chapter20: The Protists

Section: Chapter Questions

Problem 4CT: Melvin Calvin and Andrew Benson determined the steps in the light-independent reactions of...

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Melvin Calvin and Andrew Benson determined the steps in the light-independent reactions of photosynthesis by exposing the green alga Chlorella to CO2 labeled with the radioisotope carbon 14. By looking at which compounds the C14 ended up in, they were able to identify all intermediates in this cyclic pathway. Why did they predict correctly that the same set of intermediates would be formed in the light reaction in land plants?
Which part of the Calvin cycle would be affected if a cell could not produce the enzyme RuBIsCO?
Which of the following substances does not participate in the Calvin-Benson cycle? a. ATP c. NADPH e. PGAL b. O2 d. RuBP f. CO2
DRAW a curved arrow mechanism for photosynthesis with the following steps. Step 1: Absorption of sunlight and excitation of chlorophyll molecules Step 2: Transfer of energy to reaction center chlorophylls, which lose an electron and become oxidized. Step 3: Electron transfer from oxidized chlorophylls to an electron acceptor, such as a quinone molecule Step 4: Electron transfer from the quinone molecule to a chain of electron carriers, such as cytochromes, which generate a proton gradient across the thylakoid membrane Step 5: ATP synthesis by ATP synthase using the energy of the proton gradient. Step 6: Transfer of electrons from the electron carriers to the enzyme rubisco, which catalyzes the carboxylation of ribulose bisphosphate (RuBP) with CO2, forming an unstable 6-carbon intermediate. Step 7: Cleavage of the 6-carbon intermediate into two 3-carbon molecules, which are phosphorylated by ATP and reduced by NADPH to form glyceraldehyde-3-phosphate (G3P) Step 8: Conversion of G3P to…
In photosynthesis, which of the following is NOT true about the light-dependent (“light”) reaction? In photosynthesis, which of the following is NOT true about the light-dependent (“light”) reaction? Glucose is synthesized from CO2 and water during the light-dependent reaction The light-dependent reaction converts light energy to chemical energy stored in ATP The light-dependent reaction (non-cyclic) captures electrons in NADPH Light-excited electrons in chlorophyll provide the energy for ATP production None of the other four answers (All are true of the light-dependent reaction)
Which of the following defines photorespiration? The metabolic pathway by which most autotrophs use the energy of light to make sugars from carbon dioxide and water The light-independent reactions of photosynthesis Process by which electron flow through electron transfer chains sets up a hydrogen ion gradient that drives ATP formation An inefficient metabolic pathway of producing sugars that occurs when O2 attaches to rubisco
• Describe the differences in color between the leaf which was fully exposed to sunlight and the one which was covered with black paper. • Where do the protons used in the light reactions come from? • What is the significance of light reaction? • What are the products of light reactions that are used in the Calvin cycle? • What are the roles of ATP and NADPH in photosynthesis?
• Photosystems are used in which phase of photosynthesis?• Which of the following molecules is produced during the photosynthesis phase?
What are the two places where light energy is required in the light reaction of photosynthesis? Why must energy be supplied at precisely these points?
Which of the following correctly sequences the steps of non-cyclic electron transport? a) Chlorophyll molecules absorb UV radiation exciting electrons which flow through photosystem I, returning to the chlorophyll molecules b) Electrons donated from water molecules pass through photosystem I then photosystem II before returning to the chlorophyll molecules, generating ATP in the process c) Water is oxidized by the capture of light energy; these excited electrons are passed through the dark reactions, returning to chlorophyll during the final light reactions d) The ATP and NADPH generated by the reactions of photosystem II and photosystem I are utilized by the Calvin Cycle to build high energy glucose molecules
Which of the following is NOT true of photosynthesis? Light-excited electrons in chlorophyll provide the energy for ATP production The light-independent (“dark”) reaction makes glucose from carbon dioxide (CO2) and water, using energy trapped by the light-dependent reaction The light-dependent reaction captures electrons in NADPH, which are used for glucose synthesis in the light-independent (“dark”) reaction The light-independent (“dark”) reaction converts light energy to chemical energy stored in ATP None of the other four answers (all are true of photosynthesis)
Where is the electrochemical gradient located in the chloroplast? Why is it important? Why are the Light Independent Reactions important? Name the 3 stages of the Calvin Cycle? What is the function of ribulose bisphosphate, RUBISCO, glyceraldehyde 3- phosphate in the Calvin Cycle? How much energy is utilized? What is Carbon Fixation? What is Photorespiration? Why is it wasteful? Why are some plants called C4 plants and why are they important? How have they adapted to unfavorable climatic conditions? How do the activities of C4 plants compare with the activities of CAM plants?