$6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$

Question 1

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

Accepted Answer

$6CO_2 + 6H_2O + 	ext{light energy} ightarrow C_6H_{12}O_6 + 6O_2$

Question 2

During the light reactions of photosynthesis, which molecule acts as the final electron acceptor?

Accepted Answer

$NADP^+$

Question 3

Which pigment is primarily responsible for the green color of leaves and is essential for the light reactions?

Accepted Answer

Chlorophyll a

Question 4

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

Accepted Answer

To convert CO$_2$ into sugar (G3P)

Question 5

Which enzyme catalyzes the first step of carbon fixation in the Calvin cycle?

Accepted Answer

Rubisco

Question 6

In the light reactions, what is the role of the electron transport chain in the thylakoid membrane?

Accepted Answer

It pumps protons into the thylakoid space to create a proton gradient

Question 7

Which of the following statements about photorespiration is correct?

Accepted Answer

Photorespiration consumes O$_2$ and releases CO$_2$ without producing ATP or sugar

Question 8

How do CAM plants minimize water loss while still performing photosynthesis?

Accepted Answer

By opening stomata at night to fix CO$_2$ into organic acids, then using it during the day

Question 9

Which of the following best explains why plants appear green?

Accepted Answer

Chlorophyll reflects and transmits green light while absorbing other wavelengths

Question 10

A scientist exposes a plant to only green light. What is the most likely effect on the rate of photosynthesis?

Accepted Answer

It will decrease because green light is not efficiently absorbed

Question 11

Which of the following is a product of the light reactions that is directly used in the Calvin cycle?

Accepted Answer

$ATP$

Question 12

What is the main difference between C$_3$ and C$_4$ plants regarding carbon fixation?

Accepted Answer

C$_4$ plants initially fix CO$_2$ into a four-carbon compound, while C$_3$ plants fix it into a three-carbon compound

Question 13

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

Accepted Answer

Thylakoid membrane

Question 14

If a plant's thylakoid membranes were damaged, which process would be most directly affected?

Accepted Answer

Production of ATP and NADPH during the light reactions

Question 15

Which of the following best describes the role of ATP synthase in photosynthesis?

Accepted Answer

It uses the proton gradient to synthesize ATP from ADP and inorganic phosphate

Question 16

A plant is placed in an environment with no carbon dioxide. Which phase of the Calvin cycle will be directly inhibited?

Accepted Answer

Carbon fixation

Question 17

Which of the following is true about the relationship between photosynthesis and cellular respiration?

Accepted Answer

Photosynthesis stores energy in organic molecules, while cellular respiration releases energy from them

Question 18

Which molecule is regenerated during the Calvin cycle to allow the cycle to continue?

Accepted Answer

RuBP

Question 19

A mutation disables the enzyme NADP$^+$ reductase in a plant cell. What is the most immediate consequence?

Accepted Answer

The plant cannot produce NADPH, limiting the Calvin cycle

Question 20

Which of the following is a real-world application of understanding photosynthesis for addressing climate change?

Accepted Answer

Engineering plants to fix more CO$_2$ and produce more biomass

Photosynthesis: Mechanisms and Importance (Chapter 10 Study Guide)

Study Guide - Practice Questions