3-2 Energy Flow
Sep 26­7:18 PM
Autotrophs
• Organisms that capture energy from
sunlight or chemicals to produce food.
• Also called producers
Sep 26­8:09 PM
1
Photosynthesis
• Autotrophs that use light energy to
produce food (sugars)
• Release oxygen in the process
• What kinds of organisms perform
photosynthesis?
Sep 26­8:14 PM
Chemosynthesis
• Autotrophs that use chemical energy
to produce carbohydrates (sugars)
• Bacteria
• Live in hot springs, volcanic vents,
and on deep ocean floor
Sep 26­8:17 PM
2
Heterotrophs
• Acquire energy from other organisms
• Consumers
• Many different types
Sep 26­8:21 PM
Food Chains & Food Webs
• Energy flows through an ecosystem in one
direction, from the sun (or inorganic compounds) to
autotrophs and then to various heterotrophs
Sep 27­10:11 PM
3
Food Chains
• series of steps, called trophic levels
• transfer of energy among organisms
Food Webs
• feeding relationships form complex interactions
• links several food chains together
• page 71
Sep 27­10:13 PM
*Arrow points to
the organism that
consumes
Sep 27­10:22 PM
4
Ecological Pyramids
• diagram that shows the amounts of energy in
each trophic level in a food chain/web
• energy is released at each level (as heat)
• only about 10% of the energy available in one
trophic level is transferred to the next level
• Energy Pyramid - shows energy available at
each level
Sep 27­10:24 PM
Sep 27­10:31 PM
5
Biomass
• total amount of living tissue within a given trophic level
• (grams of organic matter per unit area)
• Biomass pyramid represents the potential food available
for each trophic level
Sep 27­10:28 PM
Biomass
Sep 27­10:27 PM
6
Pyramid of Numbers
• shows the number of individual organisms at
each trophic level
Sep 27­10:34 PM
Sep 28­9:09 AM
7