Q: Which of the following best describes the overall chemical equation for photosynthesis in plants?

$$6 \mathrm{CO}_2 + 12 \mathrm{H}_2\mathrm{O} + \text{Light energy} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2 + 6 \mathrm{H}_2\mathrm{O}$$

Question 1

Which of the following best describes the overall chemical equation for photosynthesis in plants?

Accepted Answer

$$6 \mathrm{CO}_2 + 12 \mathrm{H}_2\mathrm{O} + 	ext{Light energy} ightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2 + 6 \mathrm{H}_2\mathrm{O}$$

Question 2

Which structure within the chloroplast is the primary site of the light reactions of photosynthesis?

Accepted Answer

Thylakoid membrane

Question 3

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

Accepted Answer

To use ATP and NADPH to convert $$\mathrm{CO}_2$$ into sugar

Question 4

Which pigment is the primary light-capturing molecule in the light reactions of photosynthesis?

Accepted Answer

Chlorophyll a

Question 5

Why do most leaves appear green to our eyes?

Accepted Answer

They reflect and transmit green light while absorbing violet-blue and red light.

Question 6

Which of the following best explains why the action spectrum for photosynthesis is broader than the absorption spectrum of chlorophyll a?

Accepted Answer

Accessory pigments such as chlorophyll b and carotenoids absorb additional wavelengths.

Question 7

During the light reactions, what is the immediate source of electrons for the reduction of NADP+ to NADPH?

Accepted Answer

Ferredoxin (Fd)

Question 8

Which process in photosynthesis is most directly responsible for the release of oxygen gas ($$\mathrm{O}_2$$)?

Accepted Answer

Splitting of water molecules during the light reactions

Question 9

What is the role of ATP synthase in the chloroplast?

Accepted Answer

It uses the proton gradient to synthesize ATP from ADP and $$P_i.$$

Question 10

Which of the following statements about chemiosmosis in chloroplasts and mitochondria is correct?

Accepted Answer

Both generate ATP by coupling proton diffusion to phosphorylation of ADP.

Question 11

A plant is exposed to light with a wavelength of 700 nm. Which photosystem is most directly activated by this light?

Accepted Answer

Photosystem I (P700)

Question 12

Which enzyme catalyzes the fixation of carbon dioxide in the Calvin cycle?

Accepted Answer

Rubisco (RuBP carboxylase-oxygenase)

Question 13

Why is photorespiration considered a wasteful process for C3 plants?

Accepted Answer

It consumes oxygen and releases carbon dioxide without producing sugar.

Question 14

How do C4 plants minimize the cost of photorespiration?

Accepted Answer

By incorporating $$\mathrm{CO}_2$$ into a four-carbon compound in mesophyll cells

Question 15

Which adaptation allows CAM plants to survive in arid environments?

Accepted Answer

They open their stomata at night and fix $$\mathrm{CO}_2$$ into organic acids.

Question 16

A scientist isolates a pigment from a plant that absorbs light maximally at 450 nm and 680 nm. Which pigment is most likely being studied?

Accepted Answer

Chlorophyll a

Question 17

Which of the following is a direct product of the Calvin cycle?

Accepted Answer

Glyceraldehyde 3-phosphate (G3P)

Question 18

If a plant's thylakoid membranes were punctured so that the interior of the thylakoid was no longer separated from the stroma, which process would be most directly affected?

Accepted Answer

Generation of a proton gradient for ATP synthesis

Question 19

Which of the following best explains why the Calvin cycle must turn three times to produce one net G3P molecule?

Accepted Answer

Each turn fixes one $$\mathrm{CO}_2$$, and three are needed to produce enough carbon for one G3P.

Question 20

Which of the following is NOT a function of carotenoids in plants?

Accepted Answer

Directly fixing carbon dioxide in the Calvin cycle

Photosynthesis: Mechanisms, Structures, and Adaptations

Study Guide - Practice Questions

Study Guide - Flashcards