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

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 produce ATP and NADPH using energy from sunlight

Question 3

Which pigment is primarily responsible for the green color of plants and is most effective at absorbing red and blue light?

Accepted Answer

Chlorophyll

Question 4

Why do carotenoids appear yellow, orange, or red in leaves?

Accepted Answer

They reflect and transmit yellow, orange, and red wavelengths of light

Question 5

Which of the following statements about the absorption of light by pigments is correct?

Accepted Answer

Shorter wavelengths of light have more energy than longer wavelengths

Question 6

What is the fate of most excited electrons in chlorophyll after absorbing red or blue photons?

Accepted Answer

They drive photosynthesis by being transferred to an electron acceptor

Question 7

Which process in photosynthesis is directly responsible for the production of oxygen gas ($$	ext{O}_2$$)?

Accepted Answer

The splitting of water molecules by photosystem II

Question 8

What is the main role of the electron transport chain (ETC) in the thylakoid membrane during photosynthesis?

Accepted Answer

To create a proton gradient that drives ATP synthesis

Question 9

Which of the following best explains why plants appear green to the human eye?

Accepted Answer

Chlorophyll reflects and transmits green wavelengths of light

Question 10

In the Z scheme of photosynthesis, what is the final electron acceptor in the noncyclic electron flow?

Accepted Answer

NADP+

Question 11

Which of the following is a key difference between C4 and CAM plants in their strategies to minimize photorespiration?

Accepted Answer

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

Question 12

What is the main function of rubisco in the Calvin cycle?

Accepted Answer

To catalyze the fixation of carbon dioxide to ribulose-1,5-bisphosphate (RuBP)

Question 13

Which of the following best describes photorespiration?

Accepted Answer

A process where rubisco reacts with O2, leading to the release of CO2 and consumption of ATP

Question 14

Which of the following statements about cyclic electron flow in photosynthesis is correct?

Accepted Answer

It produces ATP but not NADPH and does not release oxygen

Question 15

A plant is exposed to only far-red light. Which photosystem will be most active and what is the likely effect on the rate of photosynthesis?

Accepted Answer

Photosystem I will be most active, but the overall rate of photosynthesis will be lower than if both red and far-red light are present

Question 16

Which of the following best explains why closing stomata on a hot, dry day can lead to increased photorespiration?

Accepted Answer

Closing stomata reduces CO2 entry, increasing the O2:CO2 ratio and favoring rubisco's oxygenase activity

Question 17

Which of the following is a direct product of the Calvin cycle that can be used to synthesize glucose?

Accepted Answer

Glyceraldehyde-3-phosphate (G3P)

Question 18

In C4 plants, what is the role of PEP carboxylase?

Accepted Answer

It fixes CO2 into a 4-carbon compound in mesophyll cells

Question 19

Which of the following best describes the relationship between the absorption spectrum of chlorophyll and the action spectrum of photosynthesis?

Accepted Answer

The action spectrum closely matches the absorption spectrum of chlorophyll, indicating that chlorophyll is the main pigment driving photosynthesis

Question 20

Which of the following equations represents the fixation phase of the Calvin cycle?

Accepted Answer

$$	ext{RuBP} + 	ext{CO}_2 \xrightarrow{	ext{Rubisco}} 2 	imes 3	ext{PGA}$$

Chapter 10: Photosynthesis – Mechanisms and Significance

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