Observing Cellular Respiration Lab Chapter 9 CP Biology Get out your lab journals

Introduction All living things undergo respiration. During this process, food molecules are broken down. As part of this process, animals take in oxygen and release carbon dioxide by breathing, which is easily observable. Plants do not “breathe” as animals do, so respiration in plants is not as easily observable. How do we know that plants respire? What can we observe? Brainstorm with your partners right now.

Seed Structure & Germination

Why did the indicator change color? A.Bromthymol blue is a pH indicator B.Blowing into the flask adds carbon dioxide H 2 O + CO 2 >>>> H 2 CO 3 water + carbon dioxide yields carbonic acid

Go to your lab stations now Set-up for your Lab Journal Lab Title (at the top) Lab Problems: Hypothesis for Part B: Materials Needed: List all of your lab materials as you use them. Procedures: (Summarize your procedures and draw a labeled picture of your plant set-up) Variables for Part B: Independent/Manipulated- Dependent/Responding- Controlled variables- DATA: Create the data table from the following page. Leave room to write observations. Conclusions: You will be given these questions when the lab is finished.

Lab Problems 1.How can the release of carbon dioxide by humans be observed? 2.Do plants release carbon dioxide as a product of respiration? How can we demonstrate this in the lab? Write these in your lab journal!

DATA TABLE: (Give this a GOOD Title) Tube # Contents of Tube Color of Bromthymol Blue Indicator Description of events occurring in the tube

Lab Procedures: PART A: Observing CO 2 release by humans 1.Pour 50mL of Bromthymol blue solution into your flask. This is TUBE 1: write your observations in the DATA table. 2.Now, use a straw to blow bubbles into the liquid in the flask. Be careful NOT TO INHALE while your mouth is on the straw. 3.Observe any changes in the color of the bromthymol blue solution. This is now TUBE 2: Record your observations in the DATA section.

PART B: Observing CO 2 release by plants 1.Pour blue indicator into 2 test tubes until they are 1/3 full. 2.Push part of a cotton ball into each tube so it gets moist, but not submerged in the indicator. Put the 8 radish seeds on top of ONE TUBE. 3.Stopper both test tubes. Use masking tape to label each tube and place them in the test tube rack. 4.We will re-examine these after 48 hours. Do NOT disturb the tubes once they are in the rack. Blue indicator 8 seeds stopper ½ cotton ball

What now? 1.Go back and write a GOOD hypothesis to predict what should happen in your 2 test tubes. Be sure to address any color change you expect and what should happen with the seeds. 2.Complete your list of materials needed. 3.Complete your steps for the procedure and a LABELED DRAWING of your lab set-up. 4.Identify the variables for the 2 test tubes on your table.

FOLLOW-UP: OBSERVATIONS & ANALYSIS Observing Cellular Respiration Lab

Procedures for today: 1.Observe your test tubes. A.Tube 3 = tube with NO seeds B.Tube 4 = tube with 8 radish seeds 2.Record your observations in your data table. 3.Clean your lab materials and return everything to the back table. 4.Complete the Conclusion questions for the lab. (next slide)

Conclusions: Answer the following in GOOD paragraphs. Interpret and explain your results. – Compare the reactions in tubes 2 & 4. How are they similar, what is going on? – Why were seeds used for this experiment and NOT adult plants? – How would your results have been affected if you used more seedlings or fewer seedlings? Answer the lab problems (re-word the problems so they are part of your answer) State if your hypothesis is supported and why or why not..GIVE DETAILS!! Error Analysis- what went wrong, were mistakes made, HOW COULD THESE BE CORRECTED in future trials Write a good concluding statement to summarize the information you have learned in this lab.

Everything done???? Double check your lab write-up to be sure that you have completed everything that is required for each section. Exchange lab journals with a partner; read their journal and add any comments for items they are missing or where things need to be better explained. Make corrections as necessary and then submit a good, CLEAN copy of your lab report.