Question 1

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

Accepted Answer

$6 \mathrm{CO}_2 + 6 \mathrm{H}_2\mathrm{O} \rightarrow C_6H_{12}O_6 + 6 \mathrm{O}_2$

Question 2

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

Accepted Answer

$\mathrm{NADP}^+$

Question 3

A plant is exposed to light, but its supply of NADP$^+$ is depleted. What immediate effect will this have on the light-dependent reactions?

Accepted Answer

The electron transport chain will stop because electrons have nowhere to go.

Question 4

Which of the following best explains why plants appear green to the human eye?

Accepted Answer

Chlorophyll reflects green wavelengths of light.

Question 5

If a plant is placed in an environment with no light, which process will immediately stop?

Accepted Answer

The splitting of water molecules to release electrons.

Question 6

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

Accepted Answer

$\mathrm{G3P}$ (glyceraldehyde-3-phosphate)

Question 7

A mutation causes a plant to lack Photosystem II. Which of the following would be most directly affected?

Accepted Answer

The production of $\mathrm{O}_2$ from water.

Question 8

Which of the following best describes the role of ATP and NADPH in the Calvin cycle?

Accepted Answer

They provide energy and reducing power to convert $\mathrm{CO}_2$ into sugars.

Question 9

In a laboratory experiment, a plant is supplied with water containing radioactive oxygen ($^{18}\mathrm{O}$). After photosynthesis, where would you expect to find the radioactive oxygen?

Accepted Answer

In the oxygen gas ($\mathrm{O}_2$) released by the plant.

Question 10

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

Accepted Answer

It requires ATP and NADPH produced by the light-dependent reactions.

Question 11

A plant is exposed to a herbicide that blocks the electron transport chain between Photosystem II and Photosystem I. What is the most likely immediate effect?

Accepted Answer

NADPH production will decrease.

Question 12

Which of the following best explains the importance of the light-dependent reactions for the Calvin cycle?

Accepted Answer

They provide ATP and NADPH needed for carbon fixation.

Question 13

If the concentration of $\mathrm{CO}_2$ in a plant's environment is drastically reduced, which process will be most directly affected?

Accepted Answer

The Calvin cycle's ability to fix carbon.

Question 14

Which of the following is NOT a product of the light-dependent reactions of photosynthesis?

Accepted Answer

Glucose

Question 15

A plant is genetically modified so that its thylakoid membranes are leaky to protons ($\mathrm{H}^+$). What is the most likely consequence?

Accepted Answer

ATP synthesis will decrease due to loss of the proton gradient.

Question 16

Which of the following best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?

Accepted Answer

The light-dependent reactions provide ATP and NADPH to the light-independent reactions.

Question 17

Which of the following is the primary function of the pigment molecules in the photosystems?

Accepted Answer

To absorb light energy and transfer it to the reaction center.

Question 18

A scientist measures the rate of photosynthesis in a plant and finds it increases with light intensity up to a point, then levels off. What is the most likely explanation for this plateau?

Accepted Answer

Another factor, such as $\mathrm{CO}_2$ concentration, becomes limiting.

Question 19

Which of the following best explains why the Calvin cycle is sometimes called the 'dark reactions'?

Accepted Answer

It does not require light directly, but uses products of the light reactions.

Question 20

If a plant is exposed to a chemical that inhibits Rubisco, which process will be most directly affected?

Accepted Answer

The fixation of $\mathrm{CO}_2$ in the Calvin cycle.

Photosynthesis: Chapter 7, Part 2 Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards