1. Photosynthesis

2. Autotrophs
Most Autotrophs use chlorophyll to convert light energy from the sun into food. 2

3. Autotrophs include organisms that make their own food
Autotrophs can use the sun’s energy directly
Euglena
Plant or animal? 3

4. Heterotrophs Heterotrophs can NOT directly use the sun’s energy.
They must eat! 4

5. Energy Energy can be stored in chemical bonds & then released later
Where did the energy in the candle come from?
Energy from sunlight is stored by plants as carbohydrates and lipids. Some of these lipids are waxes. Wax can also be made from petroleum…where did that energy come from? 5

6. The Photosynthesis Equation6 6

7. Copyright Pearson Prentice Hall
Plants gather the sun's energy with light-absorbing molecules called pigments.
The main pigment in plants is chlorophyll.
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8. Copyright Pearson Prentice Hall
The main pigment in plants is chlorophyll.
There are two main types of chlorophyll:
chlorophyll a
chlorophyll b
What color(s) of light do plants use? What color do they not use…how does this relate to their appearance?
100 80 60 40 20
Chlorophyll b
Estimated Absorption (%)
Chlorophyll a
Photosynthesis requires light and chlorophyll. In the graph above, notice how chlorophyll a absorbs light mostly in the blue-violet and red regions of the visible spectrum, whereas chlorophyll b absorbs light in the blue and red regions of the visible spectrum.
Wavelength (nm)
Wavelength (nm)
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9. Priestley’s Experiment 1771
Burned Candle In Bell Jar Until It Went Out.
Placed Sprig Of Mint In Bell Jar For A Few Days.
Candle Could Be Relit And Burn.
Concluded Plants Released Substance (O2) Necessary For burning. 9

10. Ingenhousz’s Experiment 1779
Repeated Priestly experiment with & without sunlight 10

11. Food serves as a source of raw materials for the cells in the body and as a source of energy.
Animal Cells
Animal
Mitochondrion
Plant
Photo Credits: left: ©Bob Gurr/DRK Photo; middle bottom: ©John Durham/Science Photo Library/Photo Researchers, Inc. ; middle top: ©Ron Boardman/Stone; right: ©Keith Porter/Photo Researchers, Inc.
Plant Cells 11