Q: Which of the following best describes the overall chemical equation for photosynthesis?

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

Question 1

Which of the following best describes the overall chemical equation for 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 2

Which pigment is primarily responsible for capturing light energy during the light reactions of photosynthesis?

Accepted Answer

Chlorophyll a

Question 3

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

Accepted Answer

To use ATP and NADPH to convert $$\mathrm{CO}_2$$ into sugar

Question 4

Which of the following statements about the light reactions is correct?

Accepted Answer

They produce ATP and NADPH, which are used in the Calvin cycle

Question 5

Why do leaves appear green to the human eye?

Accepted Answer

Chlorophyll absorbs violet-blue and red light, reflecting and transmitting green light

Question 6

Which enzyme catalyzes the first step of carbon fixation in the Calvin cycle?

Accepted Answer

Rubisco (Ribulose bisphosphate carboxylase-oxygenase)

Question 7

What is the primary difference between C4 and CAM plants in their adaptation to arid environments?

Accepted Answer

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

Question 8

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

Accepted Answer

It consumes ATP and organic fuel without producing sugar

Question 9

During the light reactions, what is the immediate source of electrons for the reduction of NADP+ to NADPH?

Accepted Answer

Photosystem I (P700)

Question 10

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

Accepted Answer

The splitting of water molecules during the light reactions

Question 11

A plant is exposed to light with a wavelength of 700 nm. Which photosystem will be most directly excited by this light?

Accepted Answer

Photosystem I (P700)

Question 12

Which of the following is a correct comparison between chemiosmosis in mitochondria and chloroplasts?

Accepted Answer

In mitochondria, protons are pumped into the intermembrane space; in chloroplasts, protons are pumped into the thylakoid space

Question 13

Which of the following is NOT a product of the light reactions of photosynthesis?

Accepted Answer

Glucose

Question 14

If a plant's thylakoid membranes were punctured so that the interior of the thylakoid was no longer separated from the stroma, which process would be most directly affected?

Accepted Answer

Synthesis of ATP

Question 15

Which of the following best explains why C4 plants are more efficient than C3 plants in hot, dry climates?

Accepted Answer

C4 plants minimize photorespiration by spatially separating carbon fixation from the Calvin cycle

Question 16

Which molecule is the direct product of the Calvin cycle and can be used to synthesize glucose and other carbohydrates?

Accepted Answer

Glyceraldehyde 3-phosphate (G3P)

Question 17

What is the role of carotenoids in photosynthesis?

Accepted Answer

They broaden the spectrum of light that can drive photosynthesis and protect chlorophyll from damage

Question 18

Which of the following best describes the flow of electrons during the light reactions of photosynthesis?

Accepted Answer

$$\mathrm{H}_2\mathrm{O} \rightarrow \mathrm{Photosystem\ II} \rightarrow \mathrm{Photosystem\ I} \rightarrow \mathrm{NADP}^+$$

Question 19

A mutation disables the enzyme ATP synthase in a plant cell. Which process would be most directly affected?

Accepted Answer

Production of ATP during the light reactions

Question 20

Which of the following is a real-world consequence of the evolution of C4 and CAM photosynthetic pathways?

Accepted Answer

They allow plants to thrive in hot, arid environments where C3 plants would lose excessive water

Photosynthesis: Mechanisms and Adaptations (Campbell Biology, Ch. 10)

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