CO 7
Chapter 7
Photosynthesis
Name a plant you have
seen recently.
Photosynthetic Organisms
1. *Organic molecules are built by
photosynthesis.
2. Plants use the raw materials:
carbon dioxide and water.
3. Chloroplasts carry out
photosynthesis.
*What is an organic molecule?
Brainstorm...
What are some careers or college
majors related to plants?
U of I - College of Agriculture
Structure of a Leaf
Make up the
vessels in
the plant to
transport
water and
food
Openings in the leaf allow for the
exchange of gasses. Guard cells
open and close these openings.
The Structure of Chloroplasts
Figure 7.2
Photosynthetic Pigments - Pigments found in chlorophyll absorb
various portions of visible light; absorption spectrum.
1. Two major photosynthetic pigments are chlorophyll a and chlorophyll b.
2. Both chlorophylls absorb violet, blue, and red wavelengths best.
3. Most green is reflected back; this is why leaves appear green.
Carotenoids are
yellow-orange
pigments which
absorb light in violet,
blue, and green
regions.
4. When chlorophyll
breaks down in fall,
the yellow-orange
pigments in leaves
are visible.
Absorption Spectrum - spectrophotometer measures the
amount of light that passes through a sample of pigments (like
crushed green leaves)
Action Spectrum - measures the rate of photosynthesis
at different wavelengths of light; measured by the rate
oxygen is produced
In one sentence summarize what this graph says about wavelengths,
color of light, absorption and photosynthesis.
Checkpoint
1. What is the relationship between the absorption spectrum and the
action spectrum?
2. How can we measure the rate of photosynthesis?
3. How is the wavelength of light related to the rate of photosynthesis?
4. A radish plant is grown
using lights of different
colors. Explain the chart.
Photosynthetic Reaction
6CO2 + 6H2O ------> C6H12O6 + 6O2
Two Sets of Reactions in Photosynthesis
1. Light reactions cannot take place unless light is
present. They are the energy-capturing reactions.
a. Water is split
b. ATP and
NADPH are
produced to
power the Calvin
Cycle
c. Oxygen is
released
2. Calvin Cycle Reactions
a. These reactions take
place in the stroma; can
occur in either the light or
the dark.
b. These are synthesis
reactions that use NADPH
and ATP to reduce CO2.
-- and make a
carbohydrate, sugar
The Light Reactions occurs in two systems: Photosystem I
and II - the creation of ATP is a complicated process
You will take a closer look at Photosystem I and Photosystem
II in the Photosystem Coloring Worksheet
Are you still confused? This is pretty
hard to visualize, but through the magic
of technology, we can watch these
processes as animations
McGraw Hill Animation
Summarize:
1. What is the purpose of the Calvin Cycle?
2. Where does the cell get its energy to perform these
reactions?
3. What is the final product?
4. Why is carbon dioxide necessary?
Fortunately....
AP Biology no longer requires the
memorization of every step of the Calvin
Cycle, but you should understand the
beginning and the end and what it's
purpose is.
Summary Statements:
What is the purpose of the Calvin Cycle?
Where does the cell get its energy to perform these reactions?
What is the final product?
Why is carbon dioxide necessary?
What Factors the Affect Photosynthesis?
1. Light Quality (color)
2. Light intensity
3. Light Period
Photosynthesis
Simulation
Waterweed
Simulator
4. Carbon Dioxide Availability
5. Water Availability
*Design an experiment to test ONE of the above factors*
Rate of Photosynthesis can be measured by the amount of
oxygen released or the amount of CO2 absorbed.
Quick Practice
Quick Practice
grana
thylakoid
stroma
O2
Pg 129b
Light & H2O
CO2
ADP
NADP
ATP
NADPH
O2
glucose
A = photosystem II
B = photosystem I
C = H20
D = Electron Transport Chain
E = ATP Synthase
AB = ATP
AC = phospholipids
AD = light (energy)
Photosynthesis Activities
1. Elodea photosynthesis rate (lab)
2. Photosynthesis alphabet book
3. Chromatography of a spinach leaf
4. Viewing elodea cells chloroplasts
5. Fall colors observation