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

$$6CO_2 + 6H_2O + \text{Light energy} \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 1

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

Accepted Answer

$$6CO_2 + 6H_2O + 	ext{Light energy} ightarrow C_6H_{12}O_6$ + 6O_2$$

Question 2

During the light-capturing reactions of photosynthesis, what is the primary fate of the electrons excited by photons in chlorophyll?

Accepted Answer

They are passed down an electron transport chain, generating a proton gradient for ATP synthesis

Question 3

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

Accepted Answer

Chlorophyll a

Question 4

Why do carotenoids play a critical role in photosynthetic organisms, especially under high light intensity?

Accepted Answer

They extend the range of light absorption and protect chlorophyll from damage by stabilizing free radicals

Question 5

What is the main function of the Z-scheme in photosynthesis?

Accepted Answer

It models the interaction between photosystems I and II, showing how electrons flow from water to NADP$$^+$$

Question 6

In the Calvin cycle, what is the role of ribulose-1,5-bisphosphate (RuBP)?

Accepted Answer

It is the initial reactant that combines with CO$$_2 to $$begin carbon fixation

Question 7

Which of the following statements about photorespiration is correct?

Accepted Answer

Photorespiration occurs when rubisco reacts with O$$_2$$ instead of CO$$_2$$, resulting in the consumption of oxygen and release of CO$$_2$$

Question 8

A scientist develops an artificial photosynthetic system that uses electricity from solar panels to catalyze the conversion of CO$$_2$$ and H$$_2O $$into O$$_2$$ and organic molecules. In this system, which high-energy molecules from natural photosynthesis are replaced by electricity?

Accepted Answer

ATP and NADPH

Question 9

Which of the following best explains why shorter wavelengths of light have more energy than longer wavelengths?

Accepted Answer

Energy of a photon is inversely proportional to its wavelength: $$E \propto \frac{1}{\lambda}$$

Question 10

In C$$_4$$ plants, how is the process of carbon fixation spatially separated from the Calvin cycle?

Accepted Answer

Carbon fixation by PEP carboxylase occurs in mesophyll cells, while the Calvin cycle occurs in bundle sheath cells

Question 11

What is the primary reason CAM plants are able to survive in hot, dry environments?

Accepted Answer

They temporally separate carbon fixation and the Calvin cycle, fixing CO$$_2 at $$night and running the Calvin cycle during the day

Question 12

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

Accepted Answer

Glyceraldehyde-3-phosphate (G3P)

Question 13

What is the main function of the proton-motive force generated during the light reactions of photosynthesis?

Accepted Answer

To drive the synthesis of ATP via ATP synthase

Question 14

Which of the following statements about the regulation of photosynthesis is correct?

Accepted Answer

Rubisco is activated by regulatory molecules produced when light is available and inhibited when CO$$_2 is $$low

Question 15

Which structure in plant cells allows for the exchange of CO$$_2$$ and O$$_2$$ between the leaf and the atmosphere?

Accepted Answer

Stomata

Question 16

In the electron transport chain of the thylakoid membrane, what is the role of plastoquinone (PQ)?

Accepted Answer

It shuttles electrons from photosystem II to the cytochrome complex and transports protons into the thylakoid lumen

Question 17

Which of the following is true about noncyclic electron flow in photosynthesis?

Accepted Answer

Electrons flow from water to NADP$$^+$$, producing both ATP and NADPH

Question 18

What is the significance of oxygenic photosynthesis in the evolution of life on Earth?

Accepted Answer

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

Question 19

Which of the following best explains the enhancement effect observed when chloroplasts are exposed to both red and far-red wavelengths of light?

Accepted Answer

Both photosystem I and II operate at maximum efficiency, increasing the overall rate of photosynthesis

Photosynthesis: Mechanisms, Pigments, and Pathways (Chapter 10 Study Guide)

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