The test-tubes shown were set up by a student to test the effect of light on the process of photosynthesis. All test-tubes contain water and bromothymol blue. (note that bromothymol blue is a chemical indicator that changes colour from blue to yellow in the presence of carbon dioxide.) The student used a straw to bubble carbon dioxide gas through each test-tube until the mixture of water and indicator turned to yellow. Equal-sized pieces of freshwater weed were added to test-tubes A and B. The test-tubes were stoppered, and black plastic was wrapped around test-tube B. All test-tubes were exposed to a light source for a period of 24 hours.
test-tube A: with aquatic plant
test-tube B: with aquatic plant and black plastic wrapped around
test-tube C: with light source
QUESTIONS
- Which test-tube represents the control? Explain.
- What hypothesis was the student testing?
- Describe the colour change, if any, in each test-tube after 24-hour period that would support the hypothesis. In each case explain the expected results.
If anyone can answer any of these questions, it would be greatly appreciated.
April 21, 2010
Photosynthesis can best be described as the conversion of light energy into chemical energy!
1). Test tube B represents the control, you have aided the experiment by putting black plastic wrap around the test tube.
2). How the rate of photosynthesis was affected by light, so to investigate the effect of light on the process of photosynthesis.
3). Well light does effect the the rate of photosynthesis.
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