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

Question 1

Which of the following best describes the main difference between autotrophs and heterotrophs?

Accepted Answer

Autotrophs produce their own organic food molecules from inorganic sources, while heterotrophs must consume organic molecules from other organisms.

Question 2

Which of the following equations correctly represents the overall reaction of photosynthesis?

Accepted Answer

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

Question 3

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

Accepted Answer

Carbon dioxide is reduced and water is oxidized.

Question 4

Which of the following statements about the light-dependent reactions of photosynthesis is correct?

Accepted Answer

They convert light energy into chemical energy stored in ATP and NADPH.

Question 5

What is the primary function of chlorophyll a in photosynthesis?

Accepted Answer

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

Question 6

Which of the following best explains why plants appear green to our eyes?

Accepted Answer

Chlorophyll reflects green light and absorbs red and blue light.

Question 7

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

Accepted Answer

It catalyzes the fixation of carbon dioxide to ribulose bisphosphate (RuBP).

Question 8

Which of the following is a correct description of photorespiration?

Accepted Answer

It is a reaction where Rubisco adds oxygen to RuBP, leading to the loss of fixed carbon and energy.

Question 9

Which of the following best describes the adaptation of C$$_4$$ plants to hot, dry environments?

Accepted Answer

They use a two-cell system to spatially separate carbon fixation from the Calvin cycle, reducing photorespiration.

Question 10

Which statement about CAM (crassulacean acid metabolism) plants is correct?

Accepted Answer

They fix CO$$_2 at $$night and release it during the day for photosynthesis.

Question 11

What is the main purpose of the light-independent reactions (Calvin cycle) in photosynthesis?

Accepted Answer

To use ATP and NADPH to convert CO$$_2$$ into glucose and other organic molecules.

Question 12

Which of the following best explains why oxygen is released during photosynthesis?

Accepted Answer

Oxygen is produced when water is split during the light-dependent reactions.

Question 13

Which of the following is a function of NADPH in photosynthesis?

Accepted Answer

It provides high-energy electrons for the reduction of carbon dioxide in the Calvin cycle.

Question 14

A plant is exposed to only green light. What is the most likely effect on its rate of photosynthesis, and why?

Accepted Answer

The rate will decrease because chlorophyll reflects green light and absorbs little of it.

Question 15

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

Accepted Answer

They regulate the exchange of gases, allowing CO$$_2 to $$enter and O$$_2 to $$exit.

Question 16

Which of the following pigments is responsible for the orange coloration in autumn leaves?

Accepted Answer

Carotenoids

Question 17

A mutation causes a plant to lack the enzyme ATP synthase in its chloroplasts. Which process would be directly affected?

Accepted Answer

The production of ATP during photophosphorylation in the light-dependent reactions.

Question 18

Which of the following best explains why photorespiration is considered wasteful for plants?

Accepted Answer

It leads to the loss of fixed carbon and consumes ATP and NADPH without producing sugars.

Question 19

Which of the following is a multi-step process that involves both the light-dependent and light-independent reactions of photosynthesis?

Accepted Answer

The conversion of light energy to chemical energy and the synthesis of glucose from CO$$_2.$$

Photosynthesis and Classification of Organisms by Food Acquisition

Study Guide - Practice Questions