Question 1

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

Accepted Answer

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

Question 2

During the light reactions of photosynthesis, which molecule is oxidized and which is reduced?

Accepted Answer

Water is oxidized; carbon dioxide is reduced.

Question 3

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

Accepted Answer

Thylakoid membrane

Question 4

Why do plant leaves appear green to the human eye?

Accepted Answer

Chlorophyll reflects green light and absorbs other wavelengths.

Question 5

Which statement correctly compares the energy of photons with different wavelengths?

Accepted Answer

Photons with shorter wavelengths have higher energy than those with longer wavelengths.

Question 6

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

Accepted Answer

To use ATP and NADPH to reduce $$CO_2$$ and produce sugars

Question 7

Which of the following is TRUE about the role of photosystem II (PSII) in the linear electron flow?

Accepted Answer

PSII absorbs light, splits water, and releases oxygen.

Question 8

What is the main purpose of the electron transport chain (ETC) in the thylakoid membrane during photosynthesis?

Accepted Answer

To create a proton gradient used to synthesize ATP via chemiosmosis

Question 9

Which pigment is the primary light absorber in most plants, and what is its main absorption peak?

Accepted Answer

Chlorophyll a; absorbs best at around 430 nm and 662 nm

Question 10

A spectrophotometer is used to measure the absorption spectrum of a pigment. If a pigment absorbs strongly at 450 nm, what color would the pigment likely appear?

Accepted Answer

It would likely appear orange or red.

Question 11

Which of the following best explains why both photosystem II and photosystem I are required for the production of NADPH in the light reactions?

Accepted Answer

Both are needed to fully energize electrons so they can reduce NADP$$^+ to $$NADPH.

Question 12

Which of the following is NOT a possible fate for the energy absorbed by a pigment molecule in a plant?

Accepted Answer

The energy is used to directly synthesize glucose.

Question 13

Which of the following statements about the absorption spectrum and action spectrum of photosynthetic pigments is correct?

Accepted Answer

The absorption spectrum shows the wavelengths a pigment absorbs; the action spectrum shows the wavelengths that drive photosynthesis.

Question 14

Which of the following best describes chemiosmosis in the context of photosynthesis?

Accepted Answer

The movement of protons across the thylakoid membrane to drive ATP synthesis

Question 15

A mutation disables the ATP synthase enzyme in the thylakoid membrane. Which process would be directly affected?

Accepted Answer

ATP production during the light reactions

Question 16

Which of the following is a correct sequence of events in the linear electron flow of photosynthesis?

Accepted Answer

Light absorption by PSII → electron transport chain → light absorption by PSI → NADPH formation

Question 17

Which of the following is a real-world consequence of the fact that only about 1% of sunlight is captured by photosynthetic organisms?

Accepted Answer

The total energy available to support life on Earth is limited by photosynthetic efficiency.

Question 18

Which of the following statements about the structure of a chloroplast is correct?

Accepted Answer

The thylakoid membrane contains chlorophyll and is the site of the light reactions.

Question 19

If a plant is exposed only to green light, what would you expect to happen to its rate of photosynthesis?

Accepted Answer

Photosynthesis would decrease because chlorophyll does not absorb green light efficiently.

Photosynthesis: Metabolic Pathways and Light Reactions (General Biology Study Notes)

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