Q: Which of the following equations correctly represents the overall process of photosynthesis?

$$6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2O + \text{light energy} \rightarrow C_6H_{12}O_6$ + 6\ \mathrm{O}_2$$

Question 1

Which of the following statements best describes the role of stomata in plant leaves?

Accepted Answer

Stomata regulate gas exchange and water loss by opening and closing via guard cells.

Question 2

During the light reactions of photosynthesis, which molecule is split to provide electrons, and what is the byproduct released?

Accepted Answer

H$$_2O is $$split, releasing O$$_2 as a $$byproduct.

Question 3

Which of the following equations correctly represents the overall process of photosynthesis?

Accepted Answer

$$6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2O + 	ext{light energy} ightarrow C_6H_{12}O_6$ + 6\ \mathrm{O}_2$$

Question 4

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

Accepted Answer

To fix carbon dioxide and produce G3P, which is used to make glucose.

Question 5

Which pigment is primarily responsible for the absorption of light in the light reactions, and why do leaves appear green?

Accepted Answer

Chlorophyll; because it reflects green light and absorbs red and blue wavelengths.

Question 6

Which of the following best explains why photorespiration is considered a wasteful process in plants?

Accepted Answer

It occurs when Rubisco binds O$$_2$$ instead of CO$$_2$$, reducing the efficiency of sugar production.

Question 7

In the light reactions, ATP is produced by which process, and where is the ATP released?

Accepted Answer

Photophosphorylation; ATP is released in the stroma.

Question 8

Which of the following statements about the electron transport chain in the light reactions is correct?

Accepted Answer

It pumps H$$^+$$ ions into the thylakoid space, creating a gradient used by ATP synthase.

Question 9

Which enzyme is responsible for carbon fixation in the Calvin cycle, and what is its significance?

Accepted Answer

Rubisco; it catalyzes the attachment of CO$$_2 to $$RuBP, initiating the Calvin cycle.

Question 10

A plant is exposed to a light source that emits only green light. What is the most likely effect on the rate of photosynthesis, and why?

Accepted Answer

The rate will decrease because green light is mostly reflected, not absorbed, by chlorophyll.

Question 11

Which of the following best describes the difference between C$$_4$$ and CAM plants in their adaptation to hot, dry climates?

Accepted Answer

C$$_4$$ plants separate carbon fixation and the Calvin cycle spatially, while CAM plants separate them temporally.

Question 12

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

Accepted Answer

G3P (glyceraldehyde-3-phosphate)

Question 13

Which of the following statements about the global significance of photosynthesis is correct?

Accepted Answer

Photosynthesis provides food and O$$_2$$ for almost all living organisms and helps moderate climate change.

Question 14

Which of the following best explains the greenhouse effect as it relates to climate change?

Accepted Answer

Greenhouse gases absorb and radiate heat back to Earth, warming the planet.

Question 15

A scientist uses radioactive oxygen isotopes to trace the source of oxygen released during photosynthesis. Which molecule is labeled, and what does this experiment demonstrate?

Accepted Answer

H$$_2O$$; it demonstrates that oxygen released comes from water.

Question 16

Which of the following is a correct comparison between photophosphorylation in chloroplasts and oxidative phosphorylation in mitochondria?

Accepted Answer

Both processes use an electron transport chain to create a proton gradient for ATP synthesis.

Question 17

If a plant's stomata remain closed during a hot, dry day, which of the following is most likely to occur?

Accepted Answer

The plant will reduce water loss but may experience increased photorespiration.

Question 18

Which of the following best describes the fate of the carbohydrates produced by photosynthesis in plants?

Accepted Answer

About half are used in cellular respiration, while others are used to build cellulose and starch.

Question 19

Which of the following is a real-world consequence of deforestation on the carbon cycle and climate change?

Accepted Answer

Deforestation reduces the uptake of CO$$_2 by $$plants, increasing atmospheric greenhouse gases.

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

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