Question 1

Which of the following best describes the role of chlorophyll in the light reactions of photosynthesis?

Accepted Answer

Chlorophyll absorbs photons and transfers the excitation energy to the reaction center, initiating electron flow.

Question 2

During the light reactions, which sequence correctly traces the path of energized electrons?

Accepted Answer

Photosystem II $$\rightarrow$$ Cytochrome complex $$\rightarrow$$ Photosystem I $$\rightarrow$$ Ferredoxin $$\rightarrow$$ NADP^+$ reductase

Question 3

Which of the following statements about the Calvin cycle is correct?

Accepted Answer

The Calvin cycle uses ATP and NADPH to reduce carbon dioxide and produce G3P.

Question 4

A plant cell is exposed to a chemical that inhibits ATP synthase. Which process would be directly affected?

Accepted Answer

The production of ATP from ADP and inorganic phosphate during the light reactions.

Question 5

Which of the following best explains why the thylakoid lumen becomes acidic during the light reactions?

Accepted Answer

Protons are actively transported into the lumen as electrons move through the electron transport chain.

Question 6

How many molecules of CO$$_2$$ are fixed and how many molecules of O$$_2$$ are produced for each molecule of glucose synthesized in photosynthesis?

Accepted Answer

$$6$$ molecules of CO$$_2$$ are fixed and $$6$$ molecules of O$$_2$$ are produced.

Question 7

Which pigment is primarily responsible for the green color of plants and is most efficient at absorbing red and blue wavelengths of light?

Accepted Answer

Chlorophyll

Question 8

What is the main function of Rubisco in the Calvin cycle?

Accepted Answer

It catalyzes the fixation of CO$$_2 to $$ribulose-1,5-bisphosphate (RuBP).

Question 9

Which of the following best describes the relationship between the absorption spectrum and the action spectrum of photosynthesis?

Accepted Answer

The action spectrum closely matches the absorption spectrum of chlorophyll, indicating that wavelengths absorbed most efficiently drive photosynthesis.

Question 10

A mutation causes a plant to lack carotenoids. Which of the following would most likely result?

Accepted Answer

The plant would be more susceptible to photooxidative damage due to lack of photoprotection.

Question 11

Which of the following is NOT a way that a proton gradient is established across the thylakoid membrane during the light reactions?

Accepted Answer

Active transport of protons from the stroma into the thylakoid lumen by the Calvin cycle enzymes.

Question 12

Which of the following best describes the process of chemiosmosis in chloroplasts?

Accepted Answer

Protons flow down their concentration gradient through ATP synthase, driving the synthesis of ATP from ADP and inorganic phosphate.

Question 13

Which of the following is the major direct product of the Calvin cycle that can be used to synthesize glucose and other organic molecules?

Accepted Answer

Glyceraldehyde-3-phosphate (G3P)

Question 14

A plant is exposed to light that only includes wavelengths in the green region of the visible spectrum. What is the most likely effect on the rate of photosynthesis?

Accepted Answer

The rate of photosynthesis would decrease because chlorophyll reflects green light and absorbs little of it.

Question 15

Which of the following best describes the difference between autotrophs and heterotrophs?

Accepted Answer

Autotrophs produce their own organic molecules from inorganic sources, while heterotrophs obtain organic molecules by consuming other organisms.

Question 16

Which of the following is a correct statement about the role of NADP^+ reductase in the light reactions?

Accepted Answer

It catalyzes the transfer of electrons from ferredoxin to NADP^+, forming NADPH.

Question 17

Which of the following is the correct order of the three phases of the Calvin cycle?

Accepted Answer

Carbon fixation $$\rightarrow$$ Reduction $$\rightarrow$$ Regeneration

Question 18

If a plant is placed in an environment with no NADP^+ available, which of the following would be the most immediate effect on the light reactions?

Accepted Answer

The production of NADPH would stop, causing electrons to accumulate on ferredoxin.

Question 19

Which of the following best explains why ATP and NADPH are both required for the Calvin cycle?

Accepted Answer

ATP provides energy and NADPH provides reducing power for the synthesis of G3P from CO$$_2.$$

Question 20

Which of the following best describes the process of resonance energy transfer in the light-harvesting complexes?

Accepted Answer

Excitation energy is transferred from one pigment molecule to another until it reaches the reaction center.

Photosynthesis: Key Concepts, Vocabulary, and Mechanisms

Guida di studio - Domande di pratica

Study guide - Flashcard