DATA SHEET
I. ROLE OF CHLOROPHYLL
Pigment Color (bottom to top) |
Pigment Name |
Distance Pigment Moved
(mm) |
Distance Solvent Moved
(mm) |
Rf
Value (nearest .01) |
QUESTIONS:
1. Use a ruler, calculator, and the chromatogram provided to calculate
the Rf value for
each of the pigments shown.
 |
2. How does chromatography separate the parts of a mixture?
3. Would each of the following factors affect the rate and distance
that the pigments
move using chromatography? (Yes or No)
a) the size
of the pigment molecules
b) type
of paper used
c) type
of solvent used
d) size
of test tube used
4. Why should care be taken not to handle chromatography paper with
your hands?
5. Where are the plant pigments located?
6. Why is it important that the pigment spot on the chromatography be
heavy and dark?
7. Did everyone get exactly the same Rf
values for the pigments in the spinach?
Explain.
8. a. Which 2 pigments were most visible in the chromatogram?
b. Are these the pigments responsible for the
leaf's original color?
c. Which 2 pigments were least visible in the
chromatograms?
d. What time of year would these pigments become
visible in the leaf?
9. List 3 possible sources of error for this portion of the lab.
II. CONSUMPTION OF CARBON DIOXIDE DURING PHOTOSYNTHESIS
| Beginning appearance of bromothymol blue |
|
| Appearance of bromothymol blue after blowing bubbles |
|
| Appearance of bromothymol blue 24 hours with Elodea |
QUESTIONS
1. a. What was the color of the bromothymol blue solution before you
blew (exhaled) into it?
b. What was its color after you blew bubbles
into it for a while?
c. Why did blowing bubbles into the solution
change its color?
2. What is the purpose of the bromothymol blue?
3. Why would the bromothymol blue change color after Elodea was placed
in it for 24 hours?
4. How might the bromothymol blue solution change if this lab was altered
so that:
a. The Elodea was placed in the dark during
the 24 hours of this lab?
b. The Elodea was left in the test tube
for 72 hours?
5. List 2 possible sources of error for this portion of the lab.
III. PRODUCTION OF OXYGEN DURING PHOTOSYNTHESIS
Amount of Light |
Position of Discs |
Position of Discs (After 24 hours) |
Percentage Floating
(After 24 hours) |
||
| Sunk | Floating | Sunk | Floating | ||
| Strong Light | 0 |
||||
| Indirect Light | 0 |
||||
| Little/No Light | 0 |
||||
QUESTIONS
1. What was the purpose of:
a. vacuuming the flasks?
b. the .2% NaHCO3 solution?
2. Why do the spinach discs eventually float?
3. Is there a pattern between the amount of light available and the
percentage of discs
floating after 24 hours? Explain
why there is or is not a pattern.
4. If plants need oxygen to “burn” their food during respiration,
why do they release
oxygen into the air?
5. Scientists now know that there are many organisms other than plants
that utilizes
photosynthesis to make food. Furthermore these
organisms must release oxygen
during this process. Name two other groups
of organisms, besides plants, that
produce and release oxygen into the air. (Use
your textbook for help)
6. List 2 possible sources of error for this portion of the lab.
IV. PRODUCTION OF GLUCOSE DURING PHOTOSYNTHESIS
|
Drawing of Starch in Plant Leaf |
QUESTIONS 1. What was the purpose of: a. Keeping the plants in the dark for 24 hours before using in this lab? b. Covering a portion of the leaf with aluminum foil? c. Boiling the leaf in water? d. Boiling the leaf in ethanol? e. Pouring Lugol’s iodine over the finished leaf? 2. Why might plants make glucose (and starch) for energy if they can already use sunlight directly to make energy? 3. Do animals make use of the glucose (starch) made by plants? Explain. |
 |
4. Would you suspect that the starch made in the leaves stay in the
leaves? Explain.
5. List 3 possible sources of error for this portion of the lab.