Chapter 10: Photosynthesis
How to Read a Chapter for Understanding
1. Read the “Concept Outline” at the beginning of the chapter.
2. Read a section of the chapter. Stop and look at the questions. If any questions
apply, use the text and your notes to answer the questions.
3. Complete the self test at the end (this is also online)
4. While you are reading, make sure to examine the pictures/graphs/diagrams
and their captions.
Questions:
1. Define oxidation and reduction in terms of electron gain or loss: gain or loss of
hydrogen and oxygen.
2. Write the summary equation for the reaction of photosynthesis.
3. Explain why almost all organisms depend upon photosynthesis to satisfy their
energy needs. Use the terms autotroph and heterotroph in your explanation
4. Briefly summarize C. B.van Niel’s experiment and discuss what it proved and
whay this was so important.
5. Explain the relationship between wavelength, energy and color in light energy.
6. Describe the experiment conducted by T.W. Englemann and what it showed.
7. Describe the general organization of a photosystem.
8. Use a diagram to trace the flow of electrons during cyclic photophosphorylation.
9. Use a diagram to trace the flow of electrons during noncyclic
photophosphorylation.
10. Explain the process of chemiosmosis in plants. How is a proton gradient
established across the thylakoid membrane? How does this result in the synthesis
of ATP?
11. Explain how the products of the light reactions are used to reduce CO2 in the
Calvin cycle to form PGAL(G3P) and describe the fate of this PGAL(G3P).
12. Draw a chloroplast, label its parts and indicate where the various photosynthetic
reactions take place.
13. What features distinguish cyclic from noncyclic photophosphorylation.
14. How are ATP and NADPH produced and utilized in photosynthesis?
15. Compare and Contrast the pathways of carbon fixation in C3 photosynthesis and
C4 photosynthesis.
16. Evolution often proceeds by “ adding on” to whatever evolved formerly. Use
what you know and the book tells you about photosynthesis to support the
suggestion that Photosystem I evolved before Photosystem II.
The Light Dependent Reactions
1. The Light Dependent Reactions of photosynthesis occur on the thylakoid membranes
of the chloroplast. Using the diagram below answer the following questions.
2. The electron pathway through the "Z scheme" is non-cyclic, where does the supply
electron come from and where do they end up?
3. What products result specifically from photosystem I and photosystem II?
4. What substances are necessary as reactants for the light dependent reactions and what
substances would be produced as a result of these reactions?
5. The diagram below illustrates the activities of light dependent reactions as they occur
on the thylakoid membranes. How is the electrochemical gradient, needed for
chemiosmosis, being established with respect to the thylakoid
membrane?
5. What three activities pictured above contribute to the strength of the electrochemical
gradient?
6. Briefly describe how the establishment of an electrochemical gradient can be used to
synthesize ATP?
The Light Independent Reactions
1. What products from the light dependent reactions will be needed in the light
independent reactions?
2. If a single molecule of carbon dioxide is fixed with each rotation of the C3 cycle, how
many rotations are necessary to construct a complete molecule of glucose? Explain!
3. To what molecule does carbon dioxide bond to in order to begin the C3 cycle?
4. List all products and reactants of the C3 cycle.
5. Make a diagram illustrating the relationship of products and reactants between the light
dependent and independent reactions.
6. What advantages does the C4 cycle offer to plants and which plants use this
method of capturing carbon dioxide?