Question 1

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

Accepted Answer

$6 \mathrm{CO}_2 + 6 \mathrm{H}_2\mathrm{O} \rightarrow C_6H_{12}O_6 + 6 \mathrm{O}_2$

Question 2

Which of the following statements correctly compares autotrophs and heterotrophs?

Accepted Answer

Autotrophs produce organic molecules from inorganic sources, while heterotrophs must consume organic molecules produced by other organisms.

Question 3

During the light reactions of photosynthesis, what is the primary function of the photosystems?

Accepted Answer

To absorb light energy and transfer excited electrons through an electron transport chain.

Question 4

Which of the following best explains why leaves appear green to our eyes?

Accepted Answer

Chlorophyll absorbs red and blue wavelengths of light and reflects green wavelengths.

Question 5

What is the main role of water in the light reactions of photosynthesis?

Accepted Answer

To provide electrons to replace those lost by chlorophyll in photosystem II.

Question 6

A plant is exposed to light of only green wavelengths. What is the most likely effect on the rate of photosynthesis?

Accepted Answer

The rate of photosynthesis will decrease because chlorophyll reflects green light.

Question 7

Which of the following is produced during the light reactions and used in the Calvin cycle?

Accepted Answer

NADPH

Question 8

If a mutation prevents the formation of ATP synthase in chloroplasts, which process would be directly affected?

Accepted Answer

The production of ATP from ADP and $\mathrm{P_i}$ during the light reactions.

Question 9

Which of the following best describes the flow of electrons during the light reactions of photosynthesis?

Accepted Answer

From water to NADP$^+$ via photosystem II and photosystem I.

Question 10

A scientist measures the absorption spectrum of a plant pigment and finds peaks at 430 nm and 662 nm. What color(s) of light does this pigment absorb most strongly?

Accepted Answer

Blue and red

Question 11

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

Accepted Answer

Glucose

Question 12

During the Calvin cycle, which molecule is directly reduced to form G3P (glyceraldehyde-3-phosphate)?

Accepted Answer

$\mathrm{CO}_2$

Question 13

Which of the following best explains why the Calvin cycle is sometimes called the 'dark reactions'?

Accepted Answer

It does not require light directly, but uses ATP and NADPH produced by the light reactions.

Question 14

If a plant is placed in an environment with no carbon dioxide, which process will be directly inhibited?

Accepted Answer

The Calvin cycle

Question 15

Which of the following best describes the relationship between the light reactions and the Calvin cycle?

Accepted Answer

The light reactions provide ATP and NADPH to the Calvin cycle.

Question 16

A plant is genetically modified so that its thylakoid membranes are leaky to protons. What is the most likely consequence?

Accepted Answer

ATP synthesis will decrease because the proton gradient cannot be maintained.

Question 17

Which of the following is a direct result of the absorption of a photon by a chlorophyll molecule?

Accepted Answer

An electron in the chlorophyll molecule is elevated to a higher energy state.

Question 18

Which of the following best describes the fate of oxygen produced during photosynthesis?

Accepted Answer

It is released as a byproduct into the atmosphere.

Question 19

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

Accepted Answer

Absorption of light by photosystem II, splitting of water, electron transport, ATP and NADPH formation

Question 20

Which of the following is NOT a phase of the Calvin cycle?

Accepted Answer

Photolysis

Photosynthesis: Structure, Function, and Importance in the Biosphere

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