Question 1

Which of the following organisms is NOT capable of performing photosynthesis?

Accepted Answer

Fungi

Question 2

What is the overall balanced chemical equation for photosynthesis in plants?

Accepted Answer

$$6 \mathrm{CO}_2 + 6 \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2$$

Question 3

Where in the chloroplast do the light-dependent reactions of photosynthesis occur?

Accepted Answer

Thylakoid membrane

Question 4

Which pigment is primarily responsible for the green color of leaves, and why?

Accepted Answer

Chlorophylls, because they reflect/transmit green light and absorb red and blue wavelengths

Question 5

Which wavelengths of visible light are most effective in driving photosynthesis?

Accepted Answer

Red and blue

Question 6

What is the main function of the light-harvesting complexes in photosystems?

Accepted Answer

To absorb light energy and transfer excitation energy to the reaction center

Question 7

During the light reactions, what is the immediate source of electrons that replace those lost by P680 in Photosystem II?

Accepted Answer

Water ($$\mathrm{H}_2\mathrm{O})$$

Question 8

What is the main outcome of the light-dependent reactions of photosynthesis?

Accepted Answer

Conversion of light energy into chemical energy in the form of ATP and NADPH

Question 9

Which of the following best describes the role of the Calvin cycle in photosynthesis?

Accepted Answer

It incorporates CO2 into organic molecules using ATP and NADPH

Question 10

Why do C4 plants have an advantage over C3 plants in hot, dry climates?

Accepted Answer

C4 plants use PEP carboxylase, which has no oxygenase activity, reducing photorespiration

Question 11

What is the main reason glucose is stored as starch in plant cells?

Accepted Answer

Starch is less osmotically active than glucose, preventing water influx

Question 12

Which of the following statements about the relationship between photosynthesis and cellular respiration is correct?

Accepted Answer

Photosynthesis is the reverse of cellular respiration in terms of reactants and products

Question 13

What is the function of RuBisCO in the Calvin cycle?

Accepted Answer

It catalyzes the fixation of CO2 to ribulose bisphosphate (RuBP)

Question 14

Photorespiration occurs when RuBisCO binds to which molecule instead of CO2?

Accepted Answer

O2

Question 15

How is the ATP/NADPH ratio required by the Calvin cycle balanced in the chloroplast?

Accepted Answer

By cyclic electron flow around Photosystem I, which produces ATP but not NADPH

Question 16

Which of the following is a byproduct of the light-dependent reactions of photosynthesis?

Accepted Answer

Oxygen

Question 17

What is the main difference between the absorption spectrum and the action spectrum of photosynthesis?

Accepted Answer

Absorption spectrum measures pigment absorbance; action spectrum measures physiological response

Question 18

Which of the following best explains why plants grown under only green light would not thrive?

Accepted Answer

Green light is mostly reflected or transmitted, not absorbed, so little energy is available for photosynthesis

Question 19

Which of the following is NOT a function of plastids in plant cells?

Accepted Answer

Production of ATP in animal cells

Question 20

A plant is placed in a sealed chamber with only blue and red LED lights. What color will the plant most likely appear, and why?

Accepted Answer

Purple, because the combination of blue and red light is absorbed, leaving little light to be reflected

Topic8 Photosynthesis: Mechanisms, Organisms, and Physiological Importance

Study Guide - Practice Questions