Skip to ContentGo to accessibility pageKeyboard shortcuts menu
OpenStax Logo
Biology for AP® Courses

Critical Thinking Questions

Biology for AP® CoursesCritical Thinking Questions
Search for key terms or text.
22 .
What are the roles of ATP and NADPH in photosynthesis?
  1. ATP and NADPH are forms of chemical energy produced from the light dependent reactions to be used in the light independent reactions that produce sugars.
  2. ATP and NADPH are forms of chemical energy produced from the light independent reactions, to be used in the light dependent reactions that produce sugars.
  3. ATP and NADPH are forms of chemical energy produced from the light dependent reactions to be used in the light independent reactions that produce proteins.
  4. ATP and NADPH are forms of chemical energy produced from the light dependent reactions to be used in the light independent reactions that use sugars as reactants.
23 .
Identify the stages of photosynthesis and the connections between those stages. Applying this knowledge, what is the overall outcome of the light-dependent reactions in photosynthesis?
  1. NADPH and ATP molecules are produced during the light-independent reactions and are used to power the light-dependent reactions.
  2. Sugar and ATP are produced during the light-dependent reactions and are used to power the light-independent reactions.
  3. Carbon dioxide and NADPH are produced during the light-independent reactions and are used to power the light-dependent reactions.
  4. NADPH and ATP molecules are produced during the light-dependent reactions and are used to power the light-independent reactions.
24 .

The photosynthesis equation is shown. According to this equation, six carbon dioxide and six water molecules produce one sugar molecule and six oxygen molecules. The sugar molecule is made of six carbons, twelve hydrogens, and six oxygens. Sunlight is used as an energy source.

Examine the illustration of the photosynthesis equation. How does the equation relate to both photosynthesis and cellular respiration, and what is the connection between the two processes?

  1. Photosynthesis utilizes energy to build carbohydrates, while cellular respiration metabolizes carbohydrates.
  2. Photosynthesis utilizes energy to metabolize carbohydrates, while cellular respiration builds carbohydrates.
  3. Photosynthesis and cellular respiration both utilize carbon dioxide and water to produce carbohydrates.
  4. Photosynthesis and cellular respiration both metabolize carbohydrates to produce carbon dioxide and water.
25 .
How is the energy from the sun transported within chloroplasts? Support your answer with details of the processes involved.
  1. When photons strike photosystem (PS) I, pigments pass the light energy to chlorophyll, molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex then transfers protons across the thylakoid membrane and transfers electrons from PS-II to PS-I. The products of the light-dependent reaction are used to power the Calvin cycle to produce glucose.
  2. When photons strike photosystem (PS) II, pigments pass the light energy to chlorophyll a molecules that in turn excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS-I to PS-II. The products of the light-dependent reaction are used to power the Calvin cycle to produce glucose.
  3. When photons strike photosystem (PS) II, pigments pass the light energy to chlorophyll a molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS-II to PS-I. The products of the light-dependent reaction are used to power the Calvin cycle to produce glucose.
  4. When photons strike photosystem (PS) II, pigments pass the light energy to chlorophyll a molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS II to PS I. The products of the light-independent reaction are used to power the Calvin cycle to produce glucose.
26 .
Refer to Figure 8.11
.
Review the many types of electromagnetic radiation as pictured on the electromagnetic spectrum. Why are X-rays and ultraviolet (UV) light wavelengths dangerous to living tissues?
  1. Because UV rays and X-rays are high-energy waves, they penetrate the tissues and thus damage cells.
  2. Because UV rays and X-rays are long-wavelength waves, they penetrate the tissues and thus damage cells.
  3. Because UV rays and X-rays are low-energy waves, they cannot penetrate tissues and thus damage cells.
  4. Because UV rays and X-rays are low-frequency waves, they can penetrate tissues and thus damage cells.
27 .
If a plant were to be exposed to only red light, would photosynthesis be possible?
  1. Photosynthesis is not possible.
  2. Photosynthesis is possible.
  3. Photosynthesis is possible only with blue light.
  4. Photosynthesis is possible only with green light.
28 .
Applying your understanding of how processes of photosynthesis are connected, select the best description of the electron transfer pathway from photosynthesis II to photosynthesis I in the light-dependent reactions.
  1. After splitting water in PS-I, high-energy electrons are delivered through the chloroplast electron transport chain to PS-II.
  2. After the photosynthesis reaction, released products like glucose help in the transfer of electrons from PS-II to PS-I.
  3. After splitting water in PS-II, high-energy electrons are delivered through the chloroplast electron transport chain to PS-I.
  4. After the completion of the light-dependent reactions, the electrons are transferred from PS-II to PS-I.
29 .
Based on your understanding of the process of photosynthesis, predict what will happen to a plant leaf that loses CO2 too quickly.
  1. This event will have no effect on the rate of photosynthesis in the leaf.
  2. Photosynthesis in the leaf will slow down or possibly stop.
  3. Photosynthesis in the leaf will increase exponentially.
  4. Photosynthesis in the leaf will first decrease and then increase.
30 .
Carbon, in the form of CO2, must be taken from the atmosphere and attached to an existing organic molecule in the Calvin cycle. Therefore, the carbon is bound to the molecule. The products of the cycle only occur because of the added carbon. What are the products of the Calvin cycle and what is regenerated?
  1. The product of the Calvin cycle is glyceraldehyde-3 phosphate and RuBP is regenerated.
  2. The product of the Calvin cycle is glyceraldehyde-3 phosphate and RuBisCO is regenerated.
  3. The product of the Calvin cycle is a 3-PGA molecule and glyceraldehyde-3 phosphate is regenerated.
  4. The product of the Calvin cycle is glyceraldehyde-3 phosphate and oxygen is regenerated.
31 .
An inadequate supply of water can compromise plants' aibility to carry out photosynthesis. How do desert plants prevent such water loss when they are subjected to high heat?
  1. by using CAM photosynthesis and by closing stomatal pores during the night
  2. by using CAM photosynthesis and by opening stomatal pores during the night
  3. by using CAM photosynthesis and by keeping stomatal pores closed at all times
  4. by bypassing CAM photosynthesis and by keeping stomatal pores closed at night
32 .
Carnivores, such as lions, are dependent on photosynthesis to survive. Considering the organisms and processes involved in carrying out photosynthesis, provide the reasoning to explain why this is the case.
  1. The prey of lions are generally herbivores, which depend on heterotrophs.
  2. The prey of lions are generally smaller carnivorous animals, which depend on non-photosynthetic organisms.
  3. The prey of lions are generally herbivores, which depend on autotrophs.
  4. The prey of lions are generally autotrophs, which depend onother autotrophs.
33 .
Refer to Figure 8.19
.
Interpret the reactions of the Calvin cycle as pictured. Why does it take three turns of the Calvin cycle to produce G3P, the initial product of photosynthesis?
  1. It takes three turns to fix enough oxygen to export one G3P molecule.
  2. It takes three turns to produce RuBisCO as an end product.
  3. It takes three turns to produce ATP and NADPH for fixation of G3P.
  4. It takes three turns to fix enough carbon to export one G3P molecule.
PreviousNext
Order a print copy
Citation/Attribution

This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute OpenStax.

Attribution information
  • If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
    Access for free at https://openstax.org/books/biology-ap-courses/pages/1-introduction
  • If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
    Access for free at https://openstax.org/books/biology-ap-courses/pages/1-introduction
Citation information

© Feb 10, 2025 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.