Question 1

Which of the following statements best describes the role of photosynthesis in the biosphere?

Accepted Answer

Photosynthesis removes CO$_2$ from the atmosphere and stores it in plant matter.

Question 2

What is the primary function of chlorophyll in plant cells?

Accepted Answer

Chlorophyll is responsible for the green color of plants and plays a central role in converting solar energy to chemical energy.

Question 3

Which equation correctly represents the overall process of photosynthesis?

Accepted Answer

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

Question 4

In the light reactions of photosynthesis, what is the fate of water (H$_2$O)?

Accepted Answer

Water is oxidized, releasing O$_2$ and providing electrons for the electron transport chain.

Question 5

Which structure in the leaf is primarily responsible for gas exchange?

Accepted Answer

Stomata

Question 6

Why do plants appear green to the human eye?

Accepted Answer

Chlorophyll transmits and reflects green wavelengths while absorbing blue-violet and red light.

Question 7

Which of the following best explains the difference between photoautotrophs and chemoautotrophs?

Accepted Answer

Photoautotrophs use the energy of light to produce organic molecules, while chemoautotrophs use inorganic chemicals.

Question 8

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

Accepted Answer

To reduce CO$_2$ to sugar using ATP and NADPH produced in the light reactions.

Question 9

Which pigment broadens the spectrum of colors that can drive photosynthesis and provides photoprotection?

Accepted Answer

Carotenoids

Question 10

What is the first step in the transformation of light energy to chemical energy in the light reactions?

Accepted Answer

Transfer of an electron from the reaction-center chlorophyll a pair to the primary electron acceptor.

Question 11

How do C$_4$ plants minimize photorespiration in hot, dry climates?

Accepted Answer

By first fixing CO$_2$ into a four-carbon compound, allowing the Calvin cycle to operate efficiently even when stomata are mostly closed.

Question 12

Which adaptation allows CAM plants to survive in arid environments?

Accepted Answer

They open their stomata at night, fix CO$_2$ into a four-carbon compound, and release it to the Calvin cycle during the day.

Question 13

Which of the following is a direct consequence of rising atmospheric CO$_2$ levels on plants, as observed in scientific studies?

Accepted Answer

Increased plant productivity and production of more potent allergenic compounds in some species.

Question 14

What is the role of the electron transport chain in the light reactions of photosynthesis?

Accepted Answer

It helps produce a concentration gradient of H$^+$ across the thylakoid membrane, driving ATP synthesis.

Question 15

Why is photosynthesis considered a redox process?

Accepted Answer

Because CO$_2$ is reduced to sugar and water is oxidized to release O$_2$.

Question 16

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

Accepted Answer

Glucose

Question 17

What is the significance of the FACE experiment in studying the effects of elevated CO$_2$ on plant ecosystems?

Accepted Answer

It allowed scientists to monitor the effects of elevated CO$_2$ on an intact forest ecosystem over a long period.

Question 18

Which process occurs when rubisco adds O$_2$ instead of CO$_2$ to RuBP, leading to a wasteful pathway in plants?

Accepted Answer

Photorespiration

Question 19

What is the global significance of photosynthesis?

Accepted Answer

It makes sugar from CO$_2$ and H$_2$O, providing food and O$_2$ for almost all living organisms.

Chapter 7: Photosynthesis – Using Light to Make Food

Study Guide - Practice Questions