$$6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2$$

Question 1

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

Accepted Answer

$$6 	ext{CO}_2 + 6 	ext{H}_2	ext{O} + 	ext{light energy} ightarrow 	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6 	ext{O}_2$$

Question 2

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

Accepted Answer

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

Question 3

Which pigment is primarily responsible for the green color of plants and the absorption of light energy during photosynthesis?

Accepted Answer

Chlorophyll

Question 4

Why do plants appear green to the human eye?

Accepted Answer

Chlorophyll reflects and transmits green wavelengths of light

Question 5

What is the role of accessory pigments such as carotenoids in photosynthesis?

Accepted Answer

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

Question 6

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

Accepted Answer

It uses ATP and NADPH produced in the light reactions to reduce CO$$_2 to $$sugar

Question 7

What is the main enzyme responsible for carbon fixation in the Calvin cycle?

Accepted Answer

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

Question 8

Which process is responsible for the production of ATP in the chloroplast during photosynthesis?

Accepted Answer

Photophosphorylation

Question 9

Why is oxygen produced during photosynthesis in plants?

Accepted Answer

Because water is split to provide electrons for photosystem II

Question 10

Which of the following best explains why the Calvin cycle is considered the most important chemical reaction on Earth?

Accepted Answer

It fixes atmospheric CO$$_2$$ into organic molecules used by almost all living organisms

Question 11

In C$$_4$$ plants, what is the main advantage of spatially separating initial carbon fixation from the Calvin cycle?

Accepted Answer

It minimizes photorespiration by increasing CO$$_2$$ concentration near Rubisco

Question 12

Which of the following is a key difference between C$$_4$$ and CAM plants?

Accepted Answer

C$$_4$$ plants separate carbon fixation and the Calvin cycle spatially, while CAM plants separate them temporally

Question 13

What is the fate of most of the G3P (glyceraldehyde-3-phosphate) produced by the Calvin cycle in a plant cell?

Accepted Answer

It is used to synthesize glucose and other carbohydrates

Question 14

Which of the following best describes the Z-scheme in photosynthesis?

Accepted Answer

It is the model describing the flow of electrons from water through photosystem II and I to NADP$$^+$$

Question 15

Which of the following is a direct result of the absorption of a photon by chlorophyll?

Accepted Answer

An electron in chlorophyll is excited to a higher energy state

Question 16

Why is Rubisco considered an inefficient enzyme?

Accepted Answer

It can catalyze the addition of both CO$$_2$$ and O$$_2 to $$RuBP, leading to photorespiration

Question 17

Which of the following statements about photorespiration is correct?

Accepted Answer

It consumes oxygen and releases fixed CO$$_2$$, reducing the efficiency of photosynthesis

Question 18

What is the main function of stomata in plant leaves?

Accepted Answer

To allow gas exchange of CO$$_2$$ and O$$_2$$ between the plant and the atmosphere

Question 19

Which of the following best explains why the evolution of oxygenic photosynthesis was critical for life on Earth?

Accepted Answer

It led to the accumulation of atmospheric oxygen, enabling aerobic respiration and the formation of the ozone layer

Question 20

Which of the following is a correct statement about the relationship between wavelength and energy of light?

Accepted Answer

Shorter wavelengths have higher energy than longer wavelengths

Photosynthesis: Harnessing Sunlight to Power Life

Study Guide - Practice Questions