Laboratory Experiment

Biology Student Name______Per____ Partner______Date ______

LABORATORY EXPERIMENT Cellular Respiration by Yeast Biology

A. Purpose: To understand conditions that influence growth and cellular respiration in yeast (Saccharomyces cerevisiae). Understand process of cell respiration by measuring diameter of balloon as measure of amount of CO2 produced, and graph results.

B. Materials: Yeast mixture Graduated Cylinders (10ml, 100ml) Glucose solution Balloon (round, 7-10 inch) Erlenmeyer flasks, 500 ml 30 cm string and ruler Beaker, 1000 ml

C. Procedures:

1. At each lab table, work in groups of two. Assign each lab partner different materials to get. 2. Fill 1000 ml BEAKER with 200 ml of water. Place on hotplate and turn on to LOW. This is your warm water bath for your experiment. (THIS PART WILL BE DONE BY YOUR TEACHER, DO NOT MAKE A HOT WATER BATH!!!) 3. Set up a clean 250 ml Erlenmeyer flask on lab table with: - 100 ml of room temp water - 2g of yeast (get from your teacher) - Sugar (you will weigh the sugar but may put in as much or as little as you like. Be sure to record the amount that you choose to put in) 4. Add ingredients to the Erlenmeyer flask. 4. Gently swirl the mixture, and quickly place a balloon over the top of the flask, making sure flask is sealed. 5. Place flask (with attached balloon) in warm water bath prepared by your teacher. 6. Measure a piece of string, yard or thread to the length of 30 cm, using a ruler. Take both, string and ruler, to the lab table to measure diameter of balloon.

1 of 5 Biology Student Name______Per____ Partner______Date ______

6. Watch your experiment and record the diameter of the balloon in intervals of 5 minutes for the duration of about 45 minutes. Record the measurements in the table below.

FLASK 1 initials_____

Amount of SUGAR Condition ______g

Diameter of balloon Time (min) Description of balloon (cm)

0 (start)

45 (end)

GRAPH….Plot the measurement of the diameter of the balloon and time on a graph and connect the points. TITLE: ______KEY: ) m c (

n o o l l a B

r e t e m a i D

Time (minutes)

Questions: 3 of 5 Biology Student Name______Per____ Partner______Date ______

1) Is yeast a living cell? How do you know? ______

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2) What is the equation for cellular respiration? ______

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3) Which organelle does cellular respiration occur in? ______

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4) What is the purpose of the balloon in this lab? What is it helping us measure? ______

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5) Did your lab work as expected? Explain why or why not. ______

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6) What could have been done to increase the rate of cellular respiration? Explain how:

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7) Which group had the most product? Why do you think they had the most? Explain.

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