Transcript Observing Respiration Lab

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
H2O + CO2 >>>> H2CO3
water + carbon dioxide yields carbonic acid
Lab Title (at the top)
Lab Problems:
Hypothesis for Part B:
Go to your lab
stations now
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/ManipulatedDependent/RespondingControlled variablesDATA:
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.
Set-up for your
Lab Journal
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
1
2
3
4
Color of
Description of
Bromthymol events occurring in
Blue
the tube
Indicator
Lab Procedures:
PART A: Observing CO2 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 CO2 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
stopper
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
8 seeds
place them in the test tube rack.
4. We will re-examine these after 48
½ cotton ball
hours. Do NOT disturb the tubes
once they are in the rack.
Blue indicator
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.
Observing Cellular Respiration Lab
FOLLOW-UP: OBSERVATIONS &
ANALYSIS
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.