1. Chapter 1.2 – How energy is transferred in the biosphere
Pages 16 – 27 in your text

2. Ecosystems have relationships based on energy and matter exchange.
To describe these we use:
Food chains
Food webs
Ecological pyramids

3. Trophic levels describe: where an organism feeds in the ecosystem
how many energy transfers an organism is from its original energy source (ie. the Sun)
How many trophic levels does this food web have?

4. Autotrophs “self feeders”:
Can produce own food.
Photosynthetic or chemosynthetic
Also called producers.
They make up 99% of all biomass.

5. obtain their energy from autotrophs or by eating another heterotrophs
also called consumers
Primary consumers feed directly on producers. They are also called herbivores.
Secondary consumers feed on primary consumers. They may be omnivores or carnivores.

6. Higher levels include: tertiary or quaternary consumers
also called top order consumers
Decomposers:
are heterotrophs
include bacteria and fungi
extract energy from dead organisms
recycle nutrients

8. The laws of thermodynamics
1st Law: energy can neither be created nor destroyed, only changed in form.
2nd Law: with each energy change, some useful energy is lost as heat.

9. The Rule of 10: Only about 10% of available energy can be passed up a level in the food chain.
What does this suggest about the number of organisms at the top trophic levels?

10. Trophic levels are described 3 ways:
food chains
food webs
ecological pyramids:
pyramid of numbers
pyramid of biomass
pyramid of energy

11. Food chain: linear series of feeding relationships.
Disadvantages:
Simplistic; show only one predator- prey relationship.
do not illustrate rule of 10

12. Food Web: series of interconnected feeding relationships
Disadvantages:
do not illustrate rule of 10
can get complicated

13. Pyramid of Numbers: producers at the bottom
population numbers at each trophic level are drawn to scale
aren’t always pyramid shaped.

14. Pyramid of Biomass:
shows the mass(kg) of living material at a trophic level.

15. Pyramid of Energy:
shows the amount of energy (J) available at each trophic level.