Download November 20th

11/20/2012
Bellringer: page 206
1. Define photosynthesis.
2. What are the ingredients needed for photosynthesis?
DLT: I can analyze the role of light and chlorophyll in
photosynthesis.
All living organisms require energy for their metabolic (chemical)
processes. The ultimate source of this energy is the sun.
Photosynthetic organisms, including plants, protists (single-celled
organisms), and blue-green algae (cyanobacteria), convert light
energy into the chemical energy of sugars, which can be used to
power metabolism. During photosynthesis, molecules referred to
as pigments (due to the wavelength, thus color, they reflect) are
used to capture light energy. Four primary pigments of green
plants can easily be separated and identified using a technique
called paper chromatography. These pigments include two
greenish pigments called chlorophylls and two yellowish pigments
called carotenoids. Pigments are separated according to
differences in their relative solubilities.
Today:
1. Set up Chromatography Lab
2. Read “Light and Pigments” on page 207 in textbook
3. Discuss lab questions
4. Exit Slip
a. Why are light and chlorophyll needed for
photosynthesis?
b. Describe the relationship between chlorophyll and the
color of plants.
c. Explain how well a plant would grow under pure yellow
light.
During winter, there is not enough light or water or
warmth for photosynthesis. The trees will rest, and
live off the food they stored during the summer.
They begin to shut down their food-making factories.
The green chlorophyll disappears from the leaves. As
the bright green fades away, we begin to see yellow
and orange colors. Small amounts of these colors
have been in the leaves all along. We just can't see
them in the summer, because they are covered up
by the green chlorophyll.
The bright reds and
purples we see in leaves are made mostly in the fall.
In some trees, like maples, glucose is trapped in the
leaves after photosynthesis stops. Sunlight and the
cool nights of autumn cause the leaves turn this
glucose into a red color. The brown color of trees like
oaks is made from wastes left in the leaves.
It is the combination of all these things that make
the beautiful fall foliage colors we enjoy each year.