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

Question 1

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

Accepted Answer

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

Question 2

What is the primary function of the light-capturing reactions in photosynthesis?

Accepted Answer

To convert light energy into chemical energy in the form of ATP and NADPH

Question 3

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

Accepted Answer

Thylakoid membrane

Question 4

Why do plants appear green to the human eye?

Accepted Answer

Chlorophyll reflects green wavelengths of light

Question 5

Which of the following pigments is primarily responsible for absorbing light energy for photosynthesis?

Accepted Answer

Chlorophyll a

Question 6

What is the main role of carotenoids in photosynthesis?

Accepted Answer

To absorb wavelengths of light not absorbed by chlorophyll and protect chlorophyll from damage

Question 7

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

Accepted Answer

Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase)

Question 8

Photorespiration occurs when Rubisco binds to which molecule instead of carbon dioxide?

Accepted Answer

Oxygen ($$O_2)$$

Question 9

What is the main ecological significance of the Calvin cycle?

Accepted Answer

It converts inorganic $$CO_2$$ into organic molecules used by living organisms

Question 10

Which adaptation allows C4 plants to minimize photorespiration in hot, dry environments?

Accepted Answer

They spatially separate initial $$CO_2$$ fixation and the Calvin cycle in different cell types

Question 11

In CAM plants, when does carbon fixation primarily occur?

Accepted Answer

At night, when stomata are open

Question 12

Which of the following best explains why the light reactions and Calvin cycle are considered 'linked'?

Accepted Answer

The ATP and NADPH produced in the light reactions are used in the Calvin cycle

Question 13

What is the fate of the majority of the sugar produced by the Calvin cycle in a plant cell?

Accepted Answer

It is used to synthesize glucose, fructose, and eventually starch or sucrose

Question 14

Which of the following statements about the electron transport chain (ETC) in chloroplasts is correct?

Accepted Answer

It creates a proton gradient that drives ATP synthesis via ATP synthase

Question 15

A plant is exposed to light that is primarily green in wavelength. What is the most likely effect on the rate of photosynthesis?

Accepted Answer

Photosynthesis will decrease because chlorophyll reflects green light

Question 16

Which of the following is a direct product of noncyclic electron flow in the light reactions?

Accepted Answer

ATP, NADPH, and $$O_2$$

Question 17

Why is photorespiration considered wasteful for plants?

Accepted Answer

It consumes oxygen and releases fixed $$CO_2$$ without producing sugar

Question 18

Which of the following best describes the role of the stoma (stomata) in plant leaves?

Accepted Answer

It allows for gas exchange, enabling $$CO_2 to $$enter and $$O_2 to $$exit

Question 19

A mutation causes a plant to lack functional ATP synthase in its thylakoid membranes. Which process would be directly affected?

Accepted Answer

Photophosphorylation

Question 20

Which of the following is a key difference between C4 and CAM photosynthetic pathways?

Accepted Answer

C4 plants separate carbon fixation and the Calvin cycle spatially, while CAM plants separate them temporally

Chapter 10: Photosynthesis – Mechanisms, Structure, and Regulation

Study Guide - Practice Questions