Question 1

Which of the following best describes the role of autotrophs in the biosphere?

Accepted Answer

They produce organic molecules from carbon dioxide and other inorganic substances.

Question 2

What is the primary function of chloroplasts in plant cells?

Accepted Answer

To convert solar energy into chemical energy through photosynthesis.

Question 3

Which equation correctly summarizes the overall process of photosynthesis?

Accepted Answer

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

Question 4

During the light reactions of photosynthesis, what is the immediate source of electrons for the electron transport chain?

Accepted Answer

Water

Question 5

Which pigment is primarily responsible for the absorption of light in the light reactions of photosynthesis?

Accepted Answer

Chlorophyll a

Question 6

What is the main product of the Calvin cycle that can be used to synthesize glucose and other carbohydrates?

Accepted Answer

Glyceraldehyde 3-phosphate (G3P)

Question 7

Which of the following statements about the Calvin cycle is correct?

Accepted Answer

It regenerates its starting material, RuBP, after molecules enter and leave the cycle.

Question 8

How many molecules of ATP and NADPH are required for the net synthesis of one G3P molecule in the Calvin cycle?

Accepted Answer

Nine ATP and six NADPH

Question 9

Which stage of photosynthesis is directly responsible for the release of oxygen?

Accepted Answer

The splitting of water during the light reactions

Question 10

What is the primary purpose of cyclic electron flow in the light reactions?

Accepted Answer

To produce ATP without generating NADPH or oxygen

Question 11

Which photosystem is best at absorbing light with a wavelength of 680 nm?

Accepted Answer

Photosystem II (P680)

Question 12

In the context of photosynthesis, what does the term 'carbon fixation' refer to?

Accepted Answer

The conversion of carbon dioxide into organic molecules

Question 13

Which molecule acts as the primary electron acceptor in the reaction center of a photosystem?

Accepted Answer

A specialized protein associated with chlorophyll a

Question 14

Why do most leaves appear green to the human eye?

Accepted Answer

Chlorophyll absorbs violet-blue and red light, reflecting and transmitting green light.

Question 15

Which of the following best explains why photosynthesis is considered an endergonic process?

Accepted Answer

It requires an input of energy from sunlight to drive the reactions.

Question 16

What is the significance of the proton gradient created during the light reactions?

Accepted Answer

It drives the synthesis of ATP by chemiosmosis.

Question 17

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

Accepted Answer

Glucose

Question 18

A plant exposed to only green light will likely:

Accepted Answer

Photosynthesize at a low rate because green light is mostly reflected.

Question 19

Which enzyme catalyzes the first step of carbon fixation in the Calvin cycle?

Accepted Answer

Rubisco (RuBP carboxylase-oxygenase)

Question 20

If a plant's thylakoid membranes were damaged, which process would be directly affected?

Accepted Answer

The light reactions, including ATP and NADPH production

Photosynthesis: Conversion of Light Energy to Chemical Energy

Study Guide - Practice Questions