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

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

Question 1

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

Accepted Answer

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

Question 2

Which pigment is primarily responsible for absorbing light energy during photosynthesis, and which wavelengths does it absorb best?

Accepted Answer

Chlorophyll a; absorbs violet and red light best

Question 3

During the light reactions of photosynthesis, what is the primary function of the electron transport chain (ETC)?

Accepted Answer

To create a proton gradient that drives ATP synthesis via ATP synthase

Question 4

Which molecule acts as the initial CO$$_2$$ acceptor in the Calvin cycle?

Accepted Answer

Ribulose-1,5-bisphosphate (RuBP)

Question 5

Why do leaves appear green to the human eye?

Accepted Answer

Chlorophyll reflects and transmits green light while absorbing most other colors

Question 6

Which of the following organisms is NOT capable of photosynthesis?

Accepted Answer

Fungi

Question 7

In the Calvin cycle, how many turns are required to produce one molecule of glyceraldehyde-3-phosphate (G3P)?

Accepted Answer

Three

Question 8

Which phase of the Calvin cycle involves the addition of CO$$_2 to $$RuBP?

Accepted Answer

Carbon fixation

Question 9

What is the role of NADPH in the Calvin cycle?

Accepted Answer

It donates electrons for the reduction of 3-phosphoglycerate to G3P

Question 10

Which experiment demonstrated that not all wavelengths of light are equally useful for photosynthesis?

Accepted Answer

George Engelmann's experiment with Spirogyra and oxygen-seeking bacteria

Question 11

What is the main function of the light-harvesting complex in a photosystem?

Accepted Answer

To capture light energy and transfer excited electrons via resonance energy to the reaction center

Question 12

Which photosystem contains the primary electron donor P700?

Accepted Answer

Photosystem I (PSI)

Question 13

What is the ultimate source of electrons for the light reactions of photosynthesis?

Accepted Answer

Water ($$\mathrm{H}_2\mathrm{O})$$

Question 14

Which of the following best explains why red light is most effective for oxygen-seeking bacteria in the Engelmann experiment?

Accepted Answer

Red light is absorbed by chlorophyll, leading to high photosynthetic activity and oxygen production

Question 15

Which process increases the potential energy of electrons by moving them from water to NADPH?

Accepted Answer

The light reactions of photosynthesis

Question 16

What is the role of ATP synthase in the thylakoid membrane?

Accepted Answer

It synthesizes ATP using the energy from a proton gradient

Question 17

Which of the following statements about autotrophs is correct?

Accepted Answer

They produce organic compounds from atmospheric carbon via photosynthesis

Question 18

In the context of photosynthesis, what are photons?

Accepted Answer

Discrete packets of light energy that transfer energy to electrons

Question 19

Which step in the Calvin cycle is directly responsible for converting inorganic carbon (CO$$_2) to a $$biologically useful form?

Accepted Answer

Carbon fixation

Question 20

If a plant is exposed only to green light, what would you expect to happen to its rate of photosynthesis?

Accepted Answer

It would decrease because chlorophyll reflects and transmits green light rather than absorbing it

Photosynthesis: Mechanisms, Pigments, and the Calvin Cycle

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