Carly , Tyler , Cara
Rachyl , Candice , Kathryn
Katherine, Nicole, Keionna
Hailey , Angel , Alexandra
Michaela , Tamilla, Lindsay
Jacob, Jessica , Jordann,
Natalia
1a.) In a graph of absorbance vs. wavelength, explain what the area
above the graph represents. (15 pts)
b.) Explain what the purpose of cutting out and weighing the graphs
was. How did you use this information in your lab report? (25 pts)
2.) Why is it reasonable to hypothesize that photosynthesis would
work better in a non-green permitting solution? (roughly two
sentences) (20pts)
3.) What material gives leaves their color? (Hint: it also used in
photosynthesis) (10pts)
Mitochondria
b) Chlorophyll
c) Electrons
d)
Polystyren
4.) DCPIP is a redox indicator and indicates when electrons are being
stolen or not. When it receives electrons, it turns from BLUE to
CLEAR. If it does not steal electrons, it stays blue.
4.) DCPIP is a redox indicator and indicates when electrons are being
stolen or not. When it receives electrons, it turns from BLUE to
CLEAR. If it does not steal electrons, it stays blue.
Indicate below which states are true or false regarding the above
information. (20 pts)
____________ If DCPIP turns clear, it has been reduced
____________ If DCPIP stays blue, it is said to be reduced
____________ If a drug blocks electrons from reaching DCPIP, the
color of DCPIP will become clear
____________ If nothing blocks DCPIP from stealing electrons, the
color of DCPIP will become clear
How?
Why?
Photosynthesis &
e transport
Pathway thinking
Evaluations
•
What did you think of the semester
(requires lab instructor to be gone)
Goals for this lab
•
Design an experiment given tools you know, a process you’ve
looked at, and a straightforward goal
•
DERIVE the purpose & implementation of ‘controls’ from your
experiment
•
SOLVE an actual question about the ‘invisible world’ through
your experimental design & execution
6
What is DCPIP?
•
What are its uses
•
What does it ‘indicate’
What is Vitamin C?
•
What do you know about Vitamin C?
•
It’s an anti...
Putting a cork in it
•
These tests confirm our claims for NEXT WEEK
•
One more thing: confirming an herbicide is a photosynthecide
•
0.15ml herbicide/ml final*
•
Blue one (DCPIP): 0.2 ml/ml*
•
To your leaf disks!
*We’re gonna be a little sloppy: ignore the change in volume
adding these produces.
9
First things first, testing
DCPIP and Herbicide
• You will test the effect of DCPIP and
Herbicide on photosynthesis
• Same approach as with the color
permitting dyes
• DCPIP: 4mls DCPIP + 20 mls buffer
• Herbicide: 3 mls Herb. + 20 mls buffer
X1
X2
Following the Scientific Approach: Predicting
The experiment’s afoot!
•
Hypothesis I: The herbicide (‘X’) acts before DCPIP has a
chance to nab the electron
•
Hypothesis II: The herbicide (‘X’) acts after DCPIP has a
chance to nab the electron
X1
•
NO reduction of DCPIP (stays
blue)
If we get this result, are we ready to publish a conclusion?
X2
•
Rampant reduction of DCPIP (turns clear)
If we get this result, are we ready to publish a conclusion?
Technical aspects I
•
Where’s the photosynthetic stuff?
•
Round I: get rid of huge chunks of
cellular debris
•
Round II: acquire chloroplasts
What goes in the
experiment tube?
What can you ’conclude’
if the DCPIP in the
solution becomes clear?
What can you
‘conclude’ if the
DCPIP in the
solution stays blue?
Homework
Come Prepared the week of Nov. 26th!!!
Fill out the back side of this worksheet in
DETAIL; use what you did today and the
protocol on pgs. 13-8 thru 13-12