Question 1

Which of the following best describes the role of autotrophs in the biosphere?

Accepted Answer

They synthesize organic compounds from $$CO_2$$ and $$H_2O$$ using light energy.

Question 2

Photosynthesis is an endergonic reaction. Which of the following statements best explains what this means?

Accepted Answer

Photosynthesis requires an input of energy to proceed.

Question 3

Where in the plant cell does the Calvin cycle occur?

Accepted Answer

Stroma of the chloroplast

Question 4

Which equation correctly represents the overall process of photosynthesis?

Accepted Answer

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

Question 5

During the light reactions of photosynthesis, what is the primary function of water?

Accepted Answer

To provide electrons to photosystem II

Question 6

Which pigment is primarily responsible for absorbing light energy in photosynthesis?

Accepted Answer

Chlorophyll a

Question 7

What is the main purpose of carotenoids in the thylakoid membrane?

Accepted Answer

To absorb and dissipate excess light energy that could damage chlorophyll

Question 8

Which of the following best describes the flow of electrons during the non-cyclic pathway of the light reactions?

Accepted Answer

Electrons are excited in PS II, transferred to PS I, and ultimately reduce NADP+ to NADPH.

Question 9

Which molecule acts as the electron carrier in the light reactions, transporting electrons to the Calvin cycle?

Accepted Answer

NADPH

Question 10

In the Calvin cycle, what is the role of the enzyme Rubisco?

Accepted Answer

It catalyzes the fixation of $$CO_2 to $$RuBP.

Question 11

Which of the following is a correct description of a redox reaction?

Accepted Answer

A reaction where electrons are transferred from one molecule to another.

Question 12

During photosynthesis, which molecule is reduced and which is oxidized?

Accepted Answer

$$CO_2 is $$reduced to glucose; H_2O is oxidized to $$O_2.$$

Question 13

Which structure in the leaf is responsible for gas exchange during photosynthesis?

Accepted Answer

Stomata

Question 14

Why do leaves appear green to our eyes?

Accepted Answer

Chlorophyll reflects green light.

Question 15

Which of the following best explains why all life on Earth depends on photosynthesis?

Accepted Answer

Photosynthesis produces oxygen and organic molecules that are essential for cellular respiration.

Question 16

A plant cell is exposed to light, but its thylakoid membranes are damaged. Which process will be most directly affected?

Accepted Answer

Production of ATP and NADPH during the light reactions

Question 17

Which of the following is a real-world consequence of carotenoids persisting longer than chlorophyll in leaves?

Accepted Answer

Leaves appear yellow and orange in the fall.

Question 18

If a plant is placed in an environment with high oxygen levels and limited NADP+, which pathway will be favored for ATP production?

Accepted Answer

Cyclic pathway using only Photosystem I

Question 19

How many turns of the Calvin cycle are required to produce one molecule of glucose?

Accepted Answer

Six

Question 20

Which of the following best describes the relationship between ATP synthase and the concentration gradient of H+ ions in the thylakoid space?

Accepted Answer

ATP synthase uses the H+ gradient to convert ADP and P into ATP.

Photosynthesis: Mechanisms, Structure, and Importance

Study Guide - Practice Questions