Download Ch 8 Photosynthesis

CO 7
Chapter 8
Photosynthesis
What is a plant anyway?
Name 3 plants you have seen
recently.
Photosynthetic Organisms
A. Photosynthesis transforms
solar energy
B. Organic molecules built by
photosynthesis provide both the
building blocks and energy for
cells.
Figure 7.1b
C. Plants use the raw materials:
carbon dioxide and water
D. Chloroplasts carry out
photosynthesis
Figure 7.1c
E. Chlorophylls and other
pigments involved in
absorption of solar energy
reside within thylakoid
membranes of chloroplasts
Figure 7.2
Plants are Solar Energy Converters
A. Solar Radiation - Only 55% of solar radiation that hits the
earth’s atmosphere reaches surface; most is visible light.
B. 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.
4. Carotenoids are
yellow-orange pigments
which absorb light in
violet, blue, and green
regions.
5. When chlorophyll
breaks down in fall, the
yellow-orange pigments
in leaves show through.
Photosynthetic Reaction
1. In 1930 C. B. Van Niel showed that O2 given off by
photosynthesis comes from water and not from CO2.
2. The net equation reads:
E. Two Sets of Reactions in Photosynthesis
1. Light reactions cannot take place unless light is present.
They are the energy-capturing reactions.
b. Chlorophyl within thylakoid membranes absorbs solar energy
and energizes electrons.
c. Energized electrons move down the electron transport
system; energy is captures and used for ATP production.
d. Energized electrons are also taken up by NADP+, becoming
NADPH.
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 Calvin Cycle
Also called
*The Light Independent Reactions
*The Dark Reactions
*Named after Melvin Calvin, who
used a radioactive isotope of
carbon to trace the reactions.
What you should know by now..
1. The equation for photosynthesis. Write it!
2. The structure of a chloroplast. Sketch it!
3. Compare Absorption Spectrum to Action Spectrum. Color it!
4. Compare the two stages of photosynthesis and their
products. Chart it!
**Things are about to get much more difficult**
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
Forest Biology - The Light Reactions
Quick Practice
Quick Practice
grana
thylakoid
stroma
O2