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

Question 1

Which of the following best describes the main function of the Calvin Cycle in photosynthesis?

Accepted Answer

To fix carbon dioxide into organic molecules using ATP and NADPH

Question 2

What is the direct product of the Calvin Cycle that can be used to build glucose and other organic molecules?

Accepted Answer

G3P (also known as PGAL)

Question 3

Which enzyme is responsible for the initial fixation of carbon dioxide in the Calvin Cycle?

Accepted Answer

Rubisco

Question 4

During the Calvin Cycle, what is the role of ATP and NADPH?

Accepted Answer

They provide energy and reducing power for the reduction of 3-phosphoglycerate to G3P

Question 5

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

Accepted Answer

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

Question 6

Why do C3 plants experience photorespiration under hot, dry conditions?

Accepted Answer

Because their stomata close, leading to a buildup of O2 and Rubisco fixing O2 instead of CO2

Question 7

Which structure on the leaf surface allows for the diffusion of CO2 into the leaf for photosynthesis?

Accepted Answer

Stomata

Question 8

How do C4 plants avoid photorespiration in hot, dry climates?

Accepted Answer

By using a specialized enzyme to fix CO2 into a 4-carbon compound in one cell, then releasing CO2 in another cell for the Calvin Cycle

Question 9

CAM plants are adapted to arid environments by:

Accepted Answer

Opening their stomata at night to take in CO2 and storing it as a 4-carbon compound for use during the day

Question 10

Which of the following best explains why the light-dependent and light-independent reactions are coupled in photosynthesis?

Accepted Answer

The Calvin Cycle requires ATP and NADPH produced by the light reactions to fix carbon and synthesize sugars

Question 11

A plant is placed in a sealed chamber with light but no CO2. Which of the following will occur?

Accepted Answer

The light reactions will continue, but the Calvin Cycle will stop due to lack of carbon fixation

Question 12

Which of the following is NOT a difference between C3, C4, and CAM plants?

Accepted Answer

The type of chlorophyll used in photosynthesis

Question 13

If a mutation caused Rubisco to lose its ability to bind CO2, what would be the most immediate effect on the Calvin Cycle?

Accepted Answer

Carbon fixation would not occur, halting the production of G3P

Question 14

Which of the following best describes carbon fixation?

Accepted Answer

The process of incorporating inorganic CO2 into organic molecules

Question 15

A scientist is studying a plant that opens its stomata only at night and stores CO2 as a 4-carbon compound. What type of plant is this?

Accepted Answer

CAM plant

Question 16

Which of the following is a consequence of photorespiration in C3 plants?

Accepted Answer

Energy is consumed and no sugar is produced

Question 17

In the Calvin Cycle, what is the fate of most of the G3P (PGAL) molecules produced?

Accepted Answer

They are used to regenerate RuBP

Question 18

Which of the following best explains why C4 and CAM plants have evolved in hot, dry climates?

Accepted Answer

To minimize water loss and avoid photorespiration by altering the timing or location of carbon fixation

Question 19

If a plant's stomata remain closed during the day for an extended period, which of the following is most likely to occur?

Accepted Answer

CO2 levels inside the leaf will decrease, slowing or stopping the Calvin Cycle

Question 20

Which of the following statements about the coupling of light-dependent and light-independent reactions is correct?

Accepted Answer

ATP and NADPH produced in the light-dependent reactions are required for the Calvin Cycle to synthesize sugars

The Calvin Cycle and Adaptations in Photosynthesis

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