9. In the light-dependent reactions electrons are released from molecules in two ways. a. Find two places in Model 2 where electrons are released from chlorophyll by a photon of light coming from the Sun. b. Find one place in Model 2 where electrons are released from water molecules. c. When the electrons are released from water molecules, what other products are formed?
4 POGIL ™ Activities for AP* Biology Read This! The light-dependent reactions of photosynthesis include three major processes: A. Excited electrons leave chlorophyll and reduce NADP + into NADPH. B. Excited electrons moving through the electron transport chain provide the free energy needed to pump hydrogen ions into the inner thylakoid. C. Hydrogen ions flowing out of the thylakoid via a protein channel provide the free energy needed to convert ADP to ATP. 10. In Model 2, label the diagram with “A,” “B,” and “C” to indicate where the three steps in the Read This! box are occurring. 11. The light-dependent reactions include an electron transport chain system that works in a very similar fashion to the electron transport chain in respiration. Briefly describe how this system works and what job it performs in the light-dependent reactions. (Your answer should include a discussion about concentration gradient.) 12. Refer to Model 2. a.Name the embedded protein complex found in the thylakoid membrane that uses excited electrons to reduce NADP+into NADPH.b.Name the embedded protein complex found in the thylakoid membrane that provides excited electrons to the electron transport chain.c.Name the embedded protein complex found in the thylakoid membrane that converts ADP to ATP using free energy from a flow of hydrogen ions.
Photosynthesis 5 13. Once a chlorophyll molecule has released electrons it is no longer useful until those electrons are replaced. a. According to Model 2, what is the source of replacement electrons for those released from photosystem I? b. According to Model 2, what is the source of replacement electrons for those released from photosystem II? 14. Is carbon dioxide involved in the light-dependent reaction? 15. Refer to Model 2. a. Write a chemical reaction that summarizes all of the chemical reactions in the light-dependent reactions of photosynthesis starting with two water molecules. b. In the photosynthesis reaction in Model 1, twelve water molecules are shown as reactants, but six water molecules are shown as products. Are any of the twelve water molecules products of the light-dependent reactions? c. Calculate the total number of oxygen, NADPH, and ATP molecules that are produced when twelve water molecules complete the light-dependent reactions. 16. Where do the ATP and NADPH produced during the light-dependent reactions go when the process is complete?
6 POGIL ™ Activities for AP* Biology Model 3 – The Light-Independent Reactions (Calvin Cycle) 1 PGAL (a three-carbon sugar used by the cell to produce glucose and other biomolecules) 6 ATP 6 ADP 3 ADP + 3 P i 3 ATP 6 PGA 6 PGAL 3 RuBP 5 PGAL 3 CO 2 6 NADPH 6 NADP + + 6H 2 O + 6 P i Phosphoglycerate (PGA) Phosphoglyceraldehyde (PGAL)
- Winter '17