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Thinking Scientifically
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  1. In the fall of the year the leaves of many trees change from green to red or yellow. Two hypotheses can explain this color change: 1) In the fall, chlorophyll degenerates and red or yellow pigments become apparent that were earlier masked by chlorophyll. 2) In the fall, red or yellow pigments are synthesized that mask the appearance of chlorophyll. How could you test these two hypotheses?
  2. You have discovered a type of bacteria that seems to be capable of photosynthesis but has no chloroplasts. However, there are invaginations of the plasma membrane inside the bacteria. Would photosynthesis be possible with such a structure? What would you expect to find in the invaginated membrane if these bacteria were photosynthetic?

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