Name_______________________________________________ Biol 211 - Group Number________ ALE 6 - Page 1 of 10 Active Learning Exercise 6. Photosynthesis Reference: Chapter 10 (Biology by Campbell/Reece, 8th ed.) Note: See the last page of this ALE for a diagram that summarizes the two stages of photosynthesis. 1. How are autotrophs different from heterotrophs? Give an example of each. 2. Give the current hypothesis that explains how eukaryotic heterotrophs are believed to have evolved to possess chloroplasts and thus become autotrophs. (Look up the endosymbiotic theory in the index of your textbook.) 3. a.) What special molecule evolved in photosynthetic autotrophs that never appeared in heterotrophs? Hint: This molecule is has a green color!! b.) What can this molecule do? Be specific! c.) What arrangement inside the chloroplast allows for a large surface area for the light dependent reactions of photosynthesis? Name the part of the chloroplast involved. 4. a.) List the approximate wavelengths of light and their respective colors that most plants absorb to energize chlorophyll for photosynthesis.ALE 6 - Biology 211 (Revised Fall 2009) ALE 6 - Page 2 of 10 4. (cont.) b.) Use the graph below to sketch the absorption spectra for chlorophyll a (solid line) and chlorophyll b (dashed line), and the action spectrum (starred line) for photosynthesis. Start by labeling the x-axis from 400 to 700 nm in increments of 100 nm. Wavelength of light (nm)Absorbance ofChlorophyll a ( __________ )andChlorophyll b ( - - - - - - )Rate ofPhotosynthesis( ********* ) c.) Explain why the combined absorption spectra for chlorophyll a and b differ from the action spectrum for photosynthesis. d.) Keeping in mind the absorption spectra of chlorophyll a and b, explain why most leaves are green. 5. The chemical equations for cellular respiration and photosynthesis are closely related. Write down the balanced net chemical equations for each and explain how they are related and how this relationship is handy for the continuation of all life on Earth. Cellular Respiration PhotosynthesisALE 6 - Biology 211 (Revised Fall 2009) ALE 6 - Page 3 of 10 6. Name the first stage of photosynthesis (it uses light!): In your own words (not the books!!) describe what happens in this stage of the process. Include in your description: what is required, what is produced, what becomes of these end products, and where in the cell all this occurs. 7. Name the second stage of photosynthesis: In your own words (not the books!) write down what happens during this stage. Include in your description: what materials are required, where they come from, what becomes of the products of this stage, and where in the cell this all occurs.ALE 6 - Biology 211 (Revised Fall 2009) ALE 6 - Page 4 of 10 8. Why is the production of G3P (glyceraldehydes-3-phosphate) during the Calvin Cycle important to a plant, and hence all life on earth? What does a plant do with the G3P made during photosynthesis? 9. a.) What two major energy-related metabolic processes do plants do during the day? Hint: one is catabolic, the other anabolic. b.) Because plants cannot store or stockpile the ATP they make during the light dependent reactions on a sunny day, what energy-related metabolic process must they do both at night and during the day to generate ATP to power cellular activities? 10. a.) Could the plant kingdom exist without animals? Explain. b.) Is it possible for just members of the plant kingdom to exist on Earth? If they could not exist without other species, what are the minimal species/kingdoms that plants would need to survive? Explain. 11. Could land animals exist without photosynthetic organisms? Explain why of why not. 12. a.) Where does the oxygen produced during photosynthesis come from, carbon dioxide or water? b.) What observations and experimental evidence supports this?ALE 6 - Biology 211 (Revised Fall 2009) ALE 6 - Page 5 of 10 13. a.) What is photorespiration? What role does Rubisco (ribulose bisphosphate carboxylase) play in photorespiration? b.)Under what conditions does photorespiration occur? c.) Is photorespiration beneficial or wasteful for plants? Explain. 14. a.) How have C4 plants evolved to minimize photorespiration? Use a labeled diagram to clarify your explanation.ALE 6 - Biology 211 (Revised Fall 2009) ALE 6 - Page 6 of 10 14. (cont.) b.) How have CAM plants evolved to minimize photorespiration? Use a labeled diagram to clarify your explanation. 15. Complete the following chart about the process of photosynthesis. Stage of Photosynthesis Inputs Outputs Location in chloroplast Light Dependent Reactions Light Independent Reactions (Calvin Cycle) 16. In the Calvin cycle, 12 G3P molecules are produced per one molecule of glucose produced. Only two of the twelve G3P molecules are siphoned off from the Calvin cycle to make glucose and other organic compounds, while the other ten G3P molecules remain in the Calvin cycle. Why aren’t all 12 G3P molecules used to make glucose? (Note: your response should address the following questions: What substance is synthesized from the ten G3P molecules? Why is it necessary to produce this substance? How many molecules of this substance are made per 10 molecules of G3P?)ALE 6 - Biology 211 (Revised Fall 2009) ALE 6 - Page 7 of 10 17. Does every plant cell carry out photosynthesis? Clearly defend your answer. 18. a.) Identify the labeled structures in the leaf cross section below. (Hint: see figures 10.3 and 35.18 on pages 187 and 751, respectively in Campbell 8th ed.) b.) In the figure above, use labeled arrows to show the route taken by the reactants of photosynthesis as they make their way to the chloroplasts in photosynthetic cells, and indicate the path taken by the products of photosynthesis Let’s now address how the structure of a leaf is efficiently adapted to perform its various functions by answering the questions that follow: c.) Why is it advantageous to have many air spaces between the photosynthetic cells in the lower layer of the leaf (i.e. the spongy mesophyll), but not in the densely packed upper layer of photosynthetic cells (i.e. the palisade mesophyll)? d.) Why are the majority of stomata located on the underside of most leaves? e.) What role