Are You Suprised ? s35

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. ______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 1 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. (Use stopwatch.com for your timer.) Design a table to record your observations:

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? ______2. Scientific Methods Evaluating Results Did the yeast produce a similar color change? Explain your answer. ______3. Scientific Methods Evaluating Results Did temperature affect the yeast’s production of carbon dioxide? Explain your answer. ______

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______4. Scientific Methods Summarizing Results What did you observe on the surface of the solutions? ______

______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. ______

Conclusion: (Include possible sources of error; what you learned about respiration; refer to data and observations from the lab.)

Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor. Holt Biology 3 Photosynthesis and Cellular Respiration