Q: What is the overall summary equation for photosynthesis?

$$6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 1

Which of the following best describes a photoautotroph?

Accepted Answer

An organism that uses light energy to synthesize organic substances from CO$$_2$$ and H$$_2O.$$

Question 2

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

Accepted Answer

Thylakoid membrane

Question 3

What is the overall summary equation for photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O + 	ext{light energy} ightarrow C_6H_{12}O_6$ + 6O_2$$

Question 4

Why is the splitting of water molecules essential to photosynthesis?

Accepted Answer

It provides electrons to replace those lost by P680 in Photosystem II.

Question 5

Which wavelengths of light are most effective for driving photosynthesis in plants?

Accepted Answer

Violet-blue (~430 nm) and red (~680 nm)

Question 6

What happens to light energy when it is absorbed by a pigment molecule in a chloroplast?

Accepted Answer

It excites an electron to a higher energy orbital.

Question 7

Which of the following best explains why leaves appear green?

Accepted Answer

Chlorophyll reflects and transmits green light while absorbing violet-blue and red light.

Question 8

What is the primary function of the Calvin Cycle in photosynthesis?

Accepted Answer

To incorporate CO$$_2$$ into organic molecules and produce sugar.

Question 9

Which of the following statements about chemiosmosis in chloroplasts and mitochondria is correct?

Accepted Answer

Both use a proton gradient across a membrane to drive ATP synthesis.

Question 10

Why is P680 considered the strongest biological oxidizing agent?

Accepted Answer

It has a high affinity for electrons and can extract them from water.

Question 11

A plant is exposed only to green light. What is the most likely outcome for its rate of photosynthesis?

Accepted Answer

It will decrease because green light is mostly reflected, not absorbed.

Question 12

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

Accepted Answer

Glyceraldehyde-3-phosphate (G3P)

Question 13

What is the role of accessory pigments such as chlorophyll b and carotenoids in photosynthesis?

Accepted Answer

They broaden the spectrum of light that can be used for photosynthesis.

Question 14

During the light reactions, which molecule acts as the final electron acceptor?

Accepted Answer

NADP$$^+$$

Question 15

Which of the following best describes the relationship between wavelength and photon energy?

Accepted Answer

Shorter wavelengths have higher photon energy.

Question 16

If a plant's stomata are closed during the day to prevent water loss, what is the most immediate effect on photosynthesis?

Accepted Answer

Decreased CO$$_2$$ uptake, limiting the Calvin Cycle

Question 17

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

Accepted Answer

Glucose

Question 18

What is the main purpose of the proton gradient established during the light reactions?

Accepted Answer

To drive ATP synthesis via ATP synthase

Question 19

Which enzyme catalyzes the first step of the Calvin Cycle and is considered the most abundant protein on Earth?

Accepted Answer

Rubisco

Question 20

A scientist measures the absorption spectrum of a pigment and finds it absorbs strongly at 430 nm and 680 nm. What color will this pigment most likely appear to the human eye?

Accepted Answer

Green

Photosynthesis: Mechanisms, Structures, and Importance

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