Mr. Miller's biology class is studying cellular respiration. To model cellular respiration, they set up an experiment containing four flasks. Each flask is the same size and are stoppered and placed under a floodlight. Each flask also contains 200 mL of H20 and 2 mL of bromothymol blue. Bromothymol blue is a chemical indicator solution that changes color from blue to yellow in the presence of CO2. The students then place a plant and/or fish into each flask (except for Flask #4 which is the control group) according to the table above. Which flask(s) will turn yellow and why?
Responses
A Flask 1 & 3 because these flasks contain plants that undergo photosynthesis.Flask 1 & 3 because these flasks contain plants that undergo photosynthesis.
B Flask 3 (only) because this is the only flask in which photosynthesis and cellular respiration are both taking place.Flask 3 (only) because this is the only flask in which photosynthesis and cellular respiration are both taking place.
C Flask 1 & 2 because there is only one process taking place in each of these flasks so the products do not get used up.Flask 1 & 2 because there is only one process taking place in each of these flasks so the products do not get used up.
D Flask 2 (only) because the fish produce CO2 as products of cellular respiration and do not undergo photosynthesis therefore not consuming CO2.
The correct answer is D. Flask 2 (only) will turn yellow because the fish in Flask 2 produce CO2 as products of cellular respiration and do not undergo photosynthesis, which means they do not consume CO2. The presence of CO2 will cause the bromothymol blue indicator solution to change color from blue to yellow.
The correct answer is B. Flask 3 (only) because this is the only flask in which photosynthesis and cellular respiration are both taking place. In flask 3, the plant undergoes photosynthesis, producing oxygen and consuming carbon dioxide. The fish also undergoes cellular respiration, producing carbon dioxide and consuming oxygen. The presence of both processes in flask 3 will result in the production of carbon dioxide, causing the bromothymol blue indicator to turn yellow.
The flask(s) that will turn yellow are Flask 1 and Flask 3. This is because these flasks contain plants that undergo photosynthesis. During photosynthesis, plants take in carbon dioxide (CO2) and release oxygen (O2). The bromothymol blue indicator solution in the flasks will change color from blue to yellow in the presence of CO2. Since the plants in Flask 1 and Flask 3 are undergoing photosynthesis and producing CO2, the solution in these flasks will turn yellow.
Flask 2 will not turn yellow because it contains fish. Fish do not undergo photosynthesis and, therefore, do not produce CO2 as a byproduct. The fish in Flask 2 produce CO2 through cellular respiration but do not consume CO2, so the bromothymol blue solution will not change color in this flask.
Flask 4 is the control group, meaning it does not contain any plants or fish. Therefore, there is no source of CO2 in this flask, so the bromothymol blue solution will remain blue.