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 component of the chloroplast is directly involved in the light reactions of photosynthesis?

Accepted Answer

Thylakoid membrane

Question 3

What is the primary function of chlorophyll in photosynthesis?

Accepted Answer

Absorbing light energy to drive the light reactions

Question 4

Which of the following statements about the Calvin cycle is correct?

Accepted Answer

It uses ATP and NADPH to convert $$\mathrm{CO}_2$$ into G3P.

Question 5

Why is the process of photosynthesis considered a redox reaction?

Accepted Answer

Because $$\mathrm{CO}_2 is $$reduced to glucose and $$\mathrm{H}_2\mathrm{O} is $$oxidized to $$\mathrm{O}_2$$

Question 6

Which color of visible light is least effective at driving photosynthesis, and why?

Accepted Answer

Green, because it is mostly reflected rather than absorbed by chlorophyll

Question 7

What is the role of the primary electron acceptor in a photosystem?

Accepted Answer

It captures excited electrons from chlorophyll a in the reaction center

Question 8

During the light reactions, what is the source of electrons for photosystem II?

Accepted Answer

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

Question 9

How does photophosphorylation generate ATP during the light reactions?

Accepted Answer

By using the energy from a proton gradient across the thylakoid membrane to power ATP synthase

Question 10

Which adaptation allows C4 and CAM plants to minimize photorespiration in hot, dry climates?

Accepted Answer

They initially fix $$\mathrm{CO}_2$$ into four-carbon compounds that release $$\mathrm{CO}_2 to $$the Calvin cycle even when stomata are closed.

Question 11

Which of the following best explains why intact chloroplasts do not release heat and light when illuminated, unlike isolated chlorophyll solutions?

Accepted Answer

Excited electrons are transferred to an electron acceptor rather than falling back to the ground state

Question 12

Which process is exergonic: photosynthesis or cellular respiration?

Accepted Answer

Cellular respiration

Question 13

What is the main significance of the Calvin cycle for the biosphere?

Accepted Answer

It converts inorganic $$\mathrm{CO}_2$$ into organic molecules used by living organisms

Question 14

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

Accepted Answer

Glyceraldehyde-3-phosphate (G3P)

Question 15

A scientist is studying the effect of increased atmospheric $$\mathrm{CO}_2 on $$plant growth. Which experimental design would best allow her to assess the long-term effects on a natural ecosystem?

Accepted Answer

Establishing field plots with elevated $$\mathrm{CO}_2$$ and comparing them to control plots over several years

Question 16

Which of the following best describes the greenhouse effect?

Accepted Answer

Heat energy is absorbed by greenhouse gases and radiated back to Earth, warming the planet

Question 17

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

Accepted Answer

Glucose

Question 18

Why is photosynthesis considered the most important process for life on Earth?

Accepted Answer

It provides food and oxygen for almost all living organisms

Question 19

Which of the following is a correct sequence of events in the light reactions?

Accepted Answer

Light absorption by photosystem II → electron transport chain → ATP synthesis → NADP+ reduction

Question 20

Which of the following is a real-world consequence of deforestation on the global carbon cycle?

Accepted Answer

It reduces the amount of $$\mathrm{CO}_2$$ removed from the atmosphere by photosynthesis

Photosynthesis: Using Light to Make Food (Campbell Biology, Ch. 7) – Study Notes

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