Do Plant Cells Undergo Both Photosynthesis and Respiration_demo Download

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Name:________________________________________________Period:___________Date:________________
Do Plant Cells Undergo Both Photosynthesis and Respiration?
Background Information:
You know that plants undergo photosynthesis, but do they also undergo cellular respiration? In this lab we will use
Anacharis, which is an aquatic plant and Bromothymol blue. Bromothymol blue is an indicator for carbon dioxide,
which means it indicates the presence or absence of carbon dioxide by changing color. Bromothymol blue is blue in
the absence of carbon dioxide, green with small amounts of carbon dioxide and yellow with high amounts of carbon
dioxide. Note that the Bromothymol blue has been diluted with water.
Materials:
test tubes
test tube rack
straw
parafilm to seal test tubes
water
tape and marking pen
Anacharis sprigs
scissors
flask
bromothymol blue
tin foil
goggles
light source
dropper
Pre-Lab:
How does bromothymol blue change color?

Original color of Bromothymol blue _________________

Color of Bromothymol blue after blowing into it for 5-10 seconds________________________

Color of Bromothymol blue after blowing into it for 30 seconds or more __________________
Equation for Photosynthesis: __________________________________________________________

_______________is taken into the plant (removed from the environment or BB) during photosynthesis
Equation for Cellular Respiration:______________________________________________________

_______________is released by the plant (added to the environment or BB) during cellular respiration
Based on the equations, what must be present for photosynthesis to occur? ___________________________
Based on the equations, what must be present for cellular respiration to occur? _________________________
Would the presence or absence of oxygen affect the color of the Bromothymol blue?
When you make your predictions, determine if all of the ingredients are present and if so is CO2 being added
to the BB or removed from the BB?
Ingredients in all the setups – water, dissolved oxygen in the water, and glucose stored in the leaves of the
plant.
Prediction Table:
Setups – All
have plant,
CO2 absent or
BB and water
present
Original
Color of
BB
Light or
Dark
1
Predicted
Color of BB
after 24
hours
Explanation – Why will the BB
be that color? What process is
happening?
Light
Absent
2
Dark
3
Light
Present
4
Dark
Results Table: Color Change of Bromothymol Blue after 24 hours.
Setups – All
Light or
Predicted
Original
have plant,
CO2 absent or
Dark
Color of BB
Color of
BB and water
present
after 24
BB
hours
1
Explanation – Why will the BB
be that color? What process is
happening?
Light
Absent
2
Dark
3
Light
Present
4
Conclusion Questions: Answer using complete
Dark
sentences on the back of this sheet.
1. What process causes bromothymol blue to turn from blue to green or yellow? Explain what is happening.
2. What process causes bromothymol blue to turn from yellow back to blue? Explain what is happening.
3. There are two setups where it was impossible for photosynthesis to occur. What are the two setups and why
was it impossible?
4. Are there any setups where cellular respiration could not occur? Explain.
5. There are two setups where both photosynthesis AND cellular respiration occurred. Which two setups are
these and explain how it is possible that both reactions occurred?