Title: Cellular Respiration Lab
In cellular respiration, the glucose produced during photosynthesis must be broken down so that the energy trapped in the glucose molecule can be changed into ATP, a form of energy that can be used by the cell. In this laboratory investigation, you will be examining cellular respiration in the following four set-ups: a) germinating seeds (seeds that are sprouting) b) dry seeds (seeds that are not sprouting but are dormant or “asleep”) c) boiled seeds d) glass beads.
To test cellular respiration, a chemical called soda lime will be used. Remember that oxygen is used by the seeds during cellular respiration, and carbon dioxide is released. Soda lime absorbs the carbon dioxide gas that is released by the seeds. The more cellular respiration occurs, the more carbon dioxide gas is absorbed by the soda lime. When a test tube with the seeds and soda-lime are placed upside down in a beaker of water, water will move into the test tube when there is more respiration going on.
Pre-lab Questions: (Answer these questions in the space provided)
1. What is the equation for cellular respiration? ___________________________________
2. According to the equation, what materials are being used during cellular respiration? (In other words, what are the reactants?) ________________________________________
3. According to the equation, what materials are being made during cellular respiration? (In other words, what are the products?) _________________________________________
4. What chemical is used in this lab to absorb the carbon dioxide released by the seeds during cellular respiration? ______________________________________________________
Problem: In which set-up will cellular respiration be the greatest: the germinating seeds, the dry dormant seeds, the boiled seeds, or the glass beads?
Hypothesis : If the test tube contains __________________________________________, then cellular respiration will be the greatest.
Procedure: (Read these procedures, then create a flow-chart on the left side of your Interactive
Notebook for each of the steps below.)
1. Fill four test tubes with approximately 1 cm of soda lime.
2. Place a small cotton plug into each of the test tubes (the cotton plug serves to keep the materials in the tube when the tube is inverted.)
3. Place 10 germinating seeds in one test tube, 10 dry, dormant seeds in another test tube, 10 boiled seeds in another test tube, then 10 glass beads in the last test tube.
4. Place another cotton plug on top of the seeds.
5. Use a rubber band to tie the four test-tubes together.
6. Fill a beaker with 1.5 centimeters of water.
7. Invert the test tubes into the beaker of water. Be careful to record the initial water line.
8. Wait 24 hours and record how much water entered each test tube in millimeters.

Diagram: The set-up below will guide you as you set-up your experiment.
Tube 1 Tube 2 Tube 3
Soda lime powder
Cotton plug
Seeds
Ruler
Cotton plug
Rubber band
Air space within tube
Beaker with water
Results:
Experimental Set-up

Germinating
Seeds

Dry, dormant
Seeds

Boiled Seeds
Height of water inside test tube in mm

Glass Beads
Post-lab questions :
1. In this lab, what evidence do you look for that proves that cellular respiration is occurring?
______________________________________________________________________
2. Of the four set-ups, which is the control group? ________________________________
Which were the experimental group(s)? _______________________________________
_______________________________________________________________________
3. What wa s the independent variable? (Hint…What condition that differed in the four testtubes?) _________________________________________________________________
4. What wa s the dependent variable? (Hint…What changes are you measuring as a result of the experiment?) __________________________________________________________
5. Which set-up demonstrated the most respiration occurring? Why? ___________________
_________________________________________________________________________
_________________________________________________________________________