$$\mathrm{RuBP} + \mathrm{CO}_2 \rightarrow 2\ \mathrm{3\text{-}phosphoglycerate}$$

Question 1

Which of the following best describes the main function of the light-dependent reactions of photosynthesis?

Accepted Answer

To convert solar energy into chemical energy in the form of ATP and NADPH

Question 2

Which molecule acts as the primary electron donor in Photosystem II during oxygenic photosynthesis?

Accepted Answer

Water ($$2H_2O)$$

Question 3

The energy content of a photon is inversely proportional to its wavelength. Which equation correctly represents this relationship?

Accepted Answer

$$E = \frac{hc}{\lambda}$$

Question 4

Which of the following pigments is primarily responsible for the absorption of light in the blue and red regions of the visible spectrum in plants?

Accepted Answer

Chlorophyll a

Question 5

What is the main role of the cytochrome b$$_6/f $$complex in the photosynthetic electron transport chain?

Accepted Answer

It transfers electrons from plastoquinol to plastocyanin and pumps protons into the thylakoid lumen

Question 6

During noncyclic electron flow, what is the final electron acceptor?

Accepted Answer

NADP$$^+$$

Question 7

Which of the following best explains why C$$_4$$ plants are more efficient than C$$_3$$ plants under hot, dry conditions?

Accepted Answer

C$$_4$$ plants spatially separate carbon fixation and the Calvin cycle, concentrating CO$$_2$$ around rubisco and minimizing photorespiration

Question 8

Which of the following is a direct product of the Calvin cycle that can be used to synthesize glucose and other carbohydrates?

Accepted Answer

Glyceraldehyde 3-phosphate (G3P)

Question 9

Photorespiration occurs when rubisco reacts with O$$_2$$ instead of CO$$_2. $$What is one consequence of this process?

Accepted Answer

CO$$_2 is $$released and ATP is consumed, reducing the efficiency of photosynthesis

Question 10

Which of the following statements about cyclic electron flow in photosynthesis is correct?

Accepted Answer

It produces ATP but not NADPH or O$$_2$$

Question 11

A plant cell is exposed to light, but the Calvin cycle is inhibited. Which of the following would you expect to accumulate?

Accepted Answer

NADPH

Question 12

Which of the following best describes the role of the oxygen-evolving complex (OEC) in photosystem II?

Accepted Answer

It catalyzes the splitting of water to release electrons, protons, and O$$_2$$

Question 13

Which of the following equations represents the fixation of CO$$_2 by $$rubisco in the Calvin cycle?

Accepted Answer

$$\mathrm{RuBP} + \mathrm{CO}_2 ightarrow 2\ \mathrm{3	ext{-}phosphoglycerate}$$

Question 14

Which of the following is a key difference between C$$_4$$ and CAM plants in their strategies to avoid photorespiration?

Accepted Answer

C$$_4$$ plants separate carbon fixation and the Calvin cycle spatially, while CAM plants separate them temporally

Question 15

If a mutation prevented the formation of plastocyanin, which process would be directly affected?

Accepted Answer

Electron transfer from the cytochrome b$$_6/f $$complex to photosystem I

Question 16

Which of the following best explains why green plants appear green?

Accepted Answer

Chlorophyll a and b absorb red and blue light but reflect green light

Question 17

During the Calvin cycle, how many turns are required to produce one molecule of glyceraldehyde 3-phosphate (G3P)?

Accepted Answer

3

Question 18

Which of the following statements about the fate of G3P produced in the Calvin cycle is correct?

Accepted Answer

Some G3P is used to regenerate RuBP, while some is used to synthesize glucose and other carbohydrates

Question 19

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

Accepted Answer

Excitation energy is transferred from one pigment molecule to another without the transfer of electrons

Photosynthesis: Phototrophic Energy Metabolism and Carbon Fixation

Study Guide - Practice Questions