1. PLANTS AND LIGHT
Plants and Light
(Photosynthesis)
(photosynthesis)

2. Autotrophs
Photoautotrophs: use light to make food – plants, cyanobacteria, algae
Chemoautotrophs: use chemicals to make food – bacteria by hydrothermal vents in ocean (H2S)

3. Electromagnetic Spectrum

4. Light Energy Sunlight ----radiation energy
----travels in waves (photons)
----mixture of all wavelengths of light
Visible Spectrum: the different colors of light that we perceive as white light
R O Y G B I V
(Low Energy  High Energy)
(Longer Wavelength----ShorterWavelength)

5. When light strikes matter
Some energy is absorbed
In photosynthetic organisms – they take this energy and store it in chemical bonds – glucose
Some energy is reflected – color you see is the color that is reflected

6. Absorption Spectrum
The different colors or wavelengths of light absorbed by a particular pigment
Red object --> reflects red --> absorbs
OYGBIV
Different for each pigment

7. Absorption Spectrum for Leaf Pigments

8. Photosynthetic Pigments
Chlorophylls – reflect green light
chlorophyll a – gathers all light energy for light dependent reactions
chlorophyll b
Carotenes – orange pigment – reflect orange light
Absorb light energy and transfer it to chlorophyll a
3. Xanthophylls – yellow pigment – reflects yellow

9. Questions ??? Why are there so many pigments?
So more wavelengths of light can be absorbed and used for photosynthesis
When do you see the carotenes and xanthophylls?
In the fall when the chlorophyll breaks down
What causes the chlorophyll to break down?
Shorter daylight hours; cooler temperatures