Name ______________________________ Class ___________________ Date __________________
Skills Practice
DATASHEET A FOR IN-TEXT LAB
Cellular Respiration
OBJECTIVES
• Demonstrate how carbon dioxide affects bromothymol blue when added to the
indicator solution.
• Describe the effect of temperature on carbon dioxide production by yeast.
MATERIALS
• safety goggles
• disposable gloves
• lab apron
• plastic cups, clear (4)
• room temperature water
• bromothymol blue
• drinking straw, plastic
• warm water
• ice water
• baker’s yeast
• ¼ teaspoon
• hand lens
• sugar
Procedure
1.
Put on safety goggles, gloves, and a lab apron. Fill a
clean plastic cup halfway with room temperature water.
Add several drops of bromothymol blue to the water.
Swirl to mix the solution.
CAUTION: Bromothymol blue is a skin and eye irritant.
2. Insert a clean straw into the solution. Gently blow a steady stream of air
through the straw. Note any changes to the solution’s appearance. CAUTION:
Be careful not to accidentally drink the solution while blowing into the
straw.
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3. Label three plastic cups “A,” “B” and “C.”
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
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Photosynthesis and Cellular Respiration
Name ______________________________ Class ___________________ Date __________________
Cellular Respiration continued
4. Fill cup A with ice water. Fill cup B with room temperature water. Fill cup C
with warm water. Add several drops of bromothymol blue solution to each
cup. This will make them all look the same.
5. Add ¼ teaspoon of baker’s yeast to each cup. Swirl the cups. Observe the
appearance of the solutions every 30 seconds. After 5 minutes, examine the
surface of each solution with a hand lens.
6.
Clean up your lab materials according to your teacher’s
instruction. Wash your hands before you leave the lab.
Analyze and Conclude
1. Drawing Conclusions What happened to the indicator (bromothymol blue) as
exhaled air bubbled through the solution? What caused this change?
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2. Scientific Methods Evaluating Results Did the yeast produce a similar
color change? Explain your answer.
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3. Scientific Methods Evaluating Results Did temperature affect the yeast’s
production of carbon dioxide? Explain your answer.
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4. Scientific Methods Summarizing Results What did you observe on the
surface of the solutions?
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
2
Photosynthesis and Cellular Respiration
Name ______________________________ Class ___________________ Date __________________
Cellular Respiration continued
5. Predicting Outcomes Will adding sugar to the yeast solution affect the
respiration rate? Make a guess. Then, design an experiment that would test the
effects of more and less sugar on yeast metabolism.
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
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Photosynthesis and Cellular Respiration