Question 1

Which of the following statements correctly distinguishes between photoautotrophs and heterotrophs?

Accepted Answer

Photoautotrophs use solar energy to produce sugars, while heterotrophs must consume organic molecules for energy.

Question 2

A scientist discovers a new bacterium in a freshwater lake that produces oxygen gas. What is the most likely explanation for this observation?

Accepted Answer

The bacterium is a photoautotroph that performs photosynthesis.

Question 3

A plant’s leaves are the primary site of photosynthesis. Which cellular structure would you expect to find in abundance in leaf cells?

Accepted Answer

Chloroplasts

Question 4

If a student is shrunk and placed inside the thylakoid space of a granum, how many phospholipid layers must they cross to exit the mesophyll cell completely?

Accepted Answer

Eight

Question 5

Which molecule provides the majority of the atoms that make up the sugar produced by photosynthesis?

Accepted Answer

Carbon dioxide

Question 6

During photosynthesis, which molecule is split to release oxygen gas?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 7

A toxin inhibits the uptake of $$\mathrm{CO_2$}$$ into plant leaves. Which process would be most directly affected?

Accepted Answer

The Calvin cycle

Question 8

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

Accepted Answer

Red wavelengths of light have less energy than violet (purple) wavelengths.

Question 9

A botanist finds a plant with blue leaves. What can be inferred about the pigments in these leaves?

Accepted Answer

The pigments absorb all visible wavelengths except blue.

Question 10

If the pair of chlorophyll a molecules is removed from the reaction-center complex of a photosystem, what is the most likely consequence?

Accepted Answer

The transfer of energy from the light-harvesting complex to the reaction-center complex would stop.

Question 11

What links photosystem II with photosystem I in the light reactions of photosynthesis?

Accepted Answer

The electrons passed between the two photosystems.

Question 12

If the passage of electrons to the primary electron acceptor of photosystem I is inhibited, what would happen to the levels of NADPH and ATP in the stroma?

Accepted Answer

Both NADPH and ATP production would stop.

Question 13

Why is it only partially accurate to refer to the Calvin cycle as the 'light-independent reactions'?

Accepted Answer

The Calvin cycle does not directly require light, but it depends on ATP and NADPH produced by the light reactions.

Question 14

Which of the following best explains why the Calvin cycle is considered cyclic?

Accepted Answer

RuBP is regenerated in the final chemical reaction.

Question 15

Which process occurs when a plant adds $$\mathrm{O_2$} to $$RuBP instead of $$\mathrm{CO_2$}$$?

Accepted Answer

Photorespiration

Question 16

Which of the following is NOT a product or benefit of photosynthesis for humans?

Accepted Answer

All of the above are benefits

Question 17

A plant uses the products of the Calvin cycle for which of the following?

Accepted Answer

All of the above

Question 18

Which adaptation allows CAM plants to minimize water loss in hot, dry climates?

Accepted Answer

They open their stomata only at night.

Question 19

Which chemical reacts with ozone ($$\mathrm{O_3$}) to $$convert it into oxygen ($$\mathrm{O_2$}$$)?

Accepted Answer

Chlorine

Question 20

Which international agreement eliminated the use of CFCs by all participating countries?

Accepted Answer

The Montreal Protocol

Guided Study: Photosynthesis and Its Global Significance

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