2. Primary Productivity
• The production of
• The process by which plants, algae, and
certain prokaryotes use light energy to
convert water and carbon dioxide into energy-
rich glucose molecules.
• The process by which certain microorganisms
use chemical energy to produce food.
5. Trophic Level
• A nourishment level
in a food chain; plant
and algae producers
constitute the lowest
level, followed by
herbivores and series
of carnivores at
6. Food Chain
• A succession
food energy is
7. Food Web
• A group of interrelated food chains.
8. Key Concept
• What factors influence a region’s
–Two factors influence a region’s
photosynthetic productivity: the
availability of nutrients and the
amount of solar radiation, or sunlight.
9. Key Concept
• Describe the transfer efficiency
between trophic levels?
–The transfer of energy between trophic
levels is very inefficient. The average
amount of energy transferred between
trophic levels is roughly 2 percent.
10. Key Concept
• What advantages do organisms in a
food web have over those in a food
–Animals that feed through a food web
rather than a food chain are more
likely to survive because they have
alternative foods to eat should one of
their food sources diminish or