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© Cengage Learning 2015
Biology Concepts and Applications | 9e
Starr | Evers | Starr
© Cengage Learning 2015
Chapter 6
Where It Starts – Photosynthesis
© 2016 Pearson Education, Inc.
Figure 7.1
PHOTOSYNTHETIC AUTOTROPHS
Plants
(mostly on land)
Photosynthetic Protists
(aquatic) Photosynthetic Bacteria
(aquatic)
Micrograph of cyanobacteria Kelp, a large, multicellular alga Forest plants
LM
Autotrophs = self feeders
Photoautotrophs – use light energy
© Cengage Learning 2015 Figure 6-1a p100
Properties of Light
Light behaves as waves and discrete packets of
energy called photons, fixed quantities of light
energy.
A pigment absorbs light of a specific wavelength
(chlorophyll a is most common).
© Cengage Learning 2015 Figure 7.6
Properties of Light
Chlorophyll absorbs light in the blue-purple and
red-orange wavelengths, but not in the green
wavelengths
WHAT is Photosynthesis?
The simplified equation for photosynthesis. A
chemical transformation of light energy to
chemical energy.
© 2013 Pearson Education, Inc.
Photosynthesis is a Redox Reaction
© 2016 Pearson Education, Inc.
Chloroplast
In the chloroplasts!
Figure 4.3-2
Chloroplast
WHERE does photosynthesis
occur?
Plant Cell
© 2016 Pearson Education, Inc.
© 2016 Pearson Education, Inc. Figure 6-4 p103
• Stroma Thick fluid inside the chloroplast
• Thylakoids Connected sacs within the chloroplast
• Grana Stacks of thylakoids
• Chlorophyll Pigment molecules that capture light energy, built into thylakoid membrane
© Cengage Learning 2015
Photosynthesis has 2 stages:
Light-Dependent Reactions & Calvin-Benson Cycle
© 2016 Pearson Education, Inc.
Figure 7.8-1
Excited state The electron falls to its ground state.
Heat
Absorption of a
photon excites an electron.
Light
Light
(fluorescence) Photon
(a) Absorption of a photon
Ground
state
e
Chlorophyll
molecule
© Cengage Learning 2015
Photosystem: group of chlorophyll,
accessory pigments, and other molecules
© Cengage Learning 2015
Electron Transport Chain
Provides energy for ATP synthesis
© Cengage Learning 2015
TWO Photosystems (II and I)
© Cengage Learning 2015
Summary of Light-Dependent
Reactions
Products = O2 (waste); ATP & NADPH (to C-B cycle)
© Cengage Learning 2015
Photosynthesis has 2 stages:
Light-Dependent Reactions & Calvin-Benson Cycle
© Cengage Learning 2015 Figure 6-8 p106
Calvin-Benson Cycle
Product = Sugar
BioFlix Animation: Photosynthesis
© 2016 Pearson Education, Inc.
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