Chapter 7
Photosynthesis: Using Light to
Make Food
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
© 2010 Pearson Education, Inc.
THE BASICS OF PHOTOSYNTHESIS
• Photosynthesis:
– Is used by plants, some protists, and some bacteria
– Transforms light energy into chemical energy
– Uses carbon dioxide and water as starting materials
• The chemical energy produced via photosynthesis is stored in
the bonds of sugar molecules.
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• Organisms that use photosynthesis are:
– Photosynthetic autotrophs
– The producers for most ecosystems
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Chloroplasts: Sites of Photosynthesis
• Chloroplasts are:
– The site of photosynthesis
– Found mostly in the interior cells of leaves
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• Stomata are tiny pores in leaves where carbon dioxide enters and
oxygen exits.
© 2010 Pearson Education, Inc.
Vein
CO2
Stomata
O2
Leaf cross section
Figure 7.2-1
The Overall Equation for Photosynthesis
In the overall equation for photosynthesis, notice that:
The reactants of photosynthesis are the waste products of
Light
cellular respiration.
energy
6 CO2
6 H2O
Carbon
dioxide
Water
C6H12O6
Photosynthesis
Glucose
6 O2
Oxygen gas
Figure 7.UN1
Sunlight energy
enters ecosystem
C6H12O6
Photosynthesis
CO2
Glucose
Carbon dioxide
O2
Oxygen
H2O
Water
Cellular respiration
ATP drives cellular work
Heat energy exits ecosystem
© 2010 Pearson Education, Inc.
Figure 6.2
THE LIGHT REACTIONS: CONVERTING
SOLAR ENERGY TO CHEMICAL ENERGY
• Chloroplasts:
– Are chemical factories powered by the sun
– Convert solar energy into chemical energy
© 2010 Pearson Education, Inc.
Increasing wavelength
10–5 nm 10–3 nm 1 nm 103 nm 106 nm
Gamma
rays
X-rays
UV
1m
MicroInfrared waves
103 m
Radio
waves
Visible light
380 400
500
Wavelength (nm)
600
700
750
Wavelength =
580
nm
Figure 7.4
Fig. 7-05
Light
Prism
Number of bacteria
Microscope slide
Bacterium
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Algal
Biologycells
with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
400
500
600
Wavelength of light (nm)
Lectures by Chris C. Romero, updated by Edward J. Zalisko
© 2010 Pearson Education, Inc.
700
Figure 7.7