Ecology is the study of interactions between organisms and their environments. There are several levels of ecological organization, including the biosphere, ecosystems, populations, and communities. Energy flows through ecosystems from producers like plants and photosynthetic bacteria to consumers at different trophic levels in food chains and webs. Only about 10% of energy is transferred from each trophic level to the next higher level.

1. Ecology!
The study of interactions among
organisms and their
environments

2. Levels of Organization


The biosphere is where all life exists
Ecosystems include living (biotic) and
non-living (abiotic) factors

3. Levels of Organization


Populations consist of organisms of the
same species living in an area
Communities have several populations
in an area
pg. 64-65

4. Energy Flow:
Producers
The SUN provides energy
 Producers make food
(autotrophic)

– Plants and some bacteria
are photosynthetic
– Some bacteria do
chemosynthesis

5. Energy Flow:
Consumers

Heterotrophs rely on other
organisms for their energy
– ie: herbivores, carnivores, omnivores,
detrivores, and decomposers

6. Food Chains

Energy is transferred through an
ecosystem when organisms eat or
are eaten

7. Trophic Levels

Feeding levels in a food chain or web
– 1st Trophic Level – Producers
– 2nd Trophic Level – 1st Order (Primary) Consumer…ETC

Each consumer depends on the trophic level
below it for energy!

8. Figure 3-8 A Food Web
Food Web
Section 3-2

Many food chains
together form a
food web
Pg. 71

9. Pyramid of Energy

10% of the energy at one trophic level
is available to the organisms at the
next level.

10. Biomass Pyramid
The amount of living tissue
and thus potential food
 Typically the greatest
biomass is at the base


11. Pyramid of Numbers
Relative number of individual
organisms at each level
 In certain ecosystems, it is NOT
pyramid shaped
