Chapter 6
Photosynthesis
Section 6-1
Capturing the
Energy in Light
Photosynthesis

Process by which part of the
energy in sunlight is transferred
to, and stored within, organic
compounds
Energy for Life Processes
Organisms that make their own
food are called autotrophs, or
producers
 Mainly plants
 Heterotrophs get their energy by
eating other organisms
 All life depends on autotrophs

Reaction
Reaction
CO2+H2O+Energy from sunlight  C6H12O6+O2
Cellular respiration is opposite
 Photosynthesis and cellular
respiration exist as a cycle
 Products of one reaction
become reactants of the next

Reaction
Chloroplasts

Chloroplast structure
 Inner and outer membrane
 Inside, flattened sacs called
thylakoids stack forming grana
 Surrounding the grana is an
aqueous solution called stroma
 Fig. 6-2, p. 112
Chloroplast
Properties of Light
White light is actually an array of
colors from red to violet (called
the visible spectrum)
 Different colors within white light
have different wavelengths

Properties of Light
Properties of Light
When light strikes an object it can
be absorbed or reflected
 Pigments are substances that
absorb certain colors of light
 Light reflected does not contain
that color

Plant Pigments

Plants contain pigments that
absorb many wavelengths of
light, but not green
 That’s why plants look green!
Tomorrow’s Lab…

We will be trying to determine
how many pigments exist in
green leaves
 Is there only one pigment, or
are there several pigments? If
so, how many??
Coming Up In Lecture…

We will be discussing the
reactions of photosynthesis…
 Light reactions (requiring light)
 Dark reactions (DO NOT require
light but may occur in the
presence of light)