Q: Which of the following equations correctly represents the net overall reaction for photosynthesis?

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

Question 1

Which of the following best describes the overall purpose of photosynthesis in photoautotrophs?

Accepted Answer

To convert the energy in sunlight into the energy stored in organic compounds.

Question 2

Which of the following equations correctly represents the net overall reaction for photosynthesis?

Accepted Answer

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

Question 3

In the context of the ecological pyramid, what is the primary role of photoautotrophs?

Accepted Answer

They capture energy from sunlight and fix it into organic compounds.

Question 4

Which structure within the chloroplast is the site of the light-dependent reactions of photosynthesis?

Accepted Answer

Thylakoid membrane

Question 5

What is the main function of pigments such as chlorophyll a and b in photosynthesis?

Accepted Answer

To absorb light energy at specific wavelengths.

Question 6

During the light-dependent reactions, what is the immediate source of electrons for Photosystem II?

Accepted Answer

Splitting of water molecules (photolysis)

Question 7

Which of the following best explains why ATP is considered unstable and useful for cellular work?

Accepted Answer

ATP contains three phosphate groups with high-energy bonds that are easily broken, releasing energy.

Question 8

What is the primary difference between cyclic and non-cyclic electron flow in the light reactions?

Accepted Answer

Cyclic flow produces only ATP, while non-cyclic flow produces both ATP and NADPH.

Question 9

Which of the following is a direct product of the light-dependent reactions that is used in the Calvin Cycle?

Accepted Answer

NADPH

Question 10

A plant is exposed to light of only 700 nm wavelength. Which photosystem will be most directly affected and what is the likely consequence for the light-dependent reactions?

Accepted Answer

Photosystem II will be less active, reducing the splitting of water and oxygen production.

Question 11

Which of the following best describes chemiosmosis in the context of the light-dependent reactions?

Accepted Answer

The movement of protons down their concentration gradient through ATP synthase to produce ATP.

Question 12

If a mutation prevented the formation of ATP synthase in the thylakoid membrane, which process would be directly impaired?

Accepted Answer

Synthesis of ATP during the light-dependent reactions

Question 13

Which of the following statements about the products of the light-dependent reactions is correct?

Accepted Answer

ATP and NADPH are produced and used to power the Calvin Cycle.

Question 14

A scientist measures the oxygen output of a plant under different light conditions. Under which condition would you expect the highest rate of oxygen production?

Accepted Answer

Bright white light containing both 680 nm and 700 nm wavelengths

Question 15

Which of the following best explains why leaves have a large surface area?

Accepted Answer

To maximize absorption of sunlight for photosynthesis

Question 16

What is the fate of the oxygen atoms from water molecules during the light-dependent reactions?

Accepted Answer

They are released as molecular oxygen ($$\mathrm{O}_2) $$into the atmosphere.

Question 17

Which of the following is NOT a product of the light-dependent reactions?

Accepted Answer

Glucose

Question 18

If a plant is unable to produce NADPH during the light-dependent reactions, which process in photosynthesis will be directly affected?

Accepted Answer

Reduction of carbon dioxide in the Calvin Cycle

Question 19

Which of the following best describes the flow of electrons during non-cyclic electron flow in the light-dependent reactions?

Accepted Answer

From water to Photosystem II to Photosystem I to NADP$$^+$$

Question 20

A mutation causes a plant to lack carotenoids. Which of the following is a likely consequence?

Accepted Answer

The plant will be less efficient at absorbing light at wavelengths not absorbed by chlorophyll.

Photosynthesis Part I: Overview & The Light-Dependent Reactions

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