1. Energy Flow Through an Ecosystem

2. Levels of Ecological Organization
Energy flows through these levels

3. Levels of Organization
Species: similar organisms that can produce fertile offspring.
Populations: individuals that are of the same species and live together

4. Q: When does a population grow? A: When more individuals grow than die
r(rate of growth)=birth rate – death rate

5. Communities: Different populations that live together in an area
Ecosystems: All the biotic and abiotic factors of an area.
Give an example of a population, community and ecosystem at ETHS

6. Q: Within an ecosystem, can there be unlimited growth of a population
Q: Within an ecosystem, can there be unlimited growth of a population? Why or Why not?
A: No, there are not unlimited resources and wastes accumulate
Carrying capacity:The population size that an environment can sustain

7. Energy Flow Through an Ecosystem
Thermodynamics: the study of energy transformations
Law 1: Energy can be transferred and changed but it CANNOT be created nor destroyed.
Energy only flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)
Sunlight is the main energy source for life on Earth
Inorganic compounds (minerals) can also be energy sources (deep ocean)

8. Trophic Level: classification of an organism based on their source of energy
Energy flows through the different levels of an ecosystem

9. 1st Trophic Level-- Producers
Can harness energy directly from their physical environment (sun)
Transform this energy into chemical energy
used as food, combine or break down molecules, make cells…
Called autotrophs because they can make their own food
Examples: plants, bacteria and some algae

10. 2nd Trophic Level -- Consumers:
Organisms that rely on other organisms for chemical energy
Cannot harness energy directly from their physical environment
Called heterotrophs because they cannot make their own food
Examples: animals, fungi, many bacteria
Q: Do all consumers eat the same thing?

11. Herbivores: Energy source comes from eating only producers
Also called primary consumers
Examples: cows, caterpillars, ducks, deer

12. 3rd Trophic Level-- secondary consumers
Organisms whose energy source comes from other consumers
Divided into two groups
Omnivores
Carnivores

13. Omnivores:
Eat both consumers and producers
Examples: bears, crows, humans
Carnivores:
Only eat other consumers
Considered “meat eaters”
Examples: tigers, snakes, owls, dogs

14. 4th Trophic Level -- Top Carnivores
Carnivores that consume other carnivores
Example: a hawk that eats a snake

15. Detritivores and Decomposers:
Consumers whose energy source comes from waste and dead bodies from organisms of all trophic levels
Cause decay or the break down of molecules
Examples: scavengers, bacteria, fungi
Q: Why are detritivores and decomposers useful?

16. Food Chain: Shows only one path of energy flow
Food Web: Shows multiple paths of energy flow

17. Some is stored in the body used later for things like growth
Q: What happens to the energy?
Some is stored in the body used later for things like growth
Some is lost in waste
what the body can’t digest or already has enough of
Most leaves as heat
Only about 10% of available energy is actually transferred from one trophic level to the next
as you go up in trophic levels, the amount of useable energy goes down

18. Primary Consumers (45,000 cal)
Energy Pyramid
Producers (450,000 cal)
Primary Consumers (45,000 cal)
Secondary Consumers
(4,500 cal)
Top Consumers
(450 cal)
Energy is lost
One calorie = the amount of energy needed to raise the temp of 1g (1mL) water 1ºC

19. Energy pyramids are NOT drawn based on the # of organisms at that level
Energy pyramids ARE drawn based on biomass and amount of available energy at that level
Biomass = total amount of living tissue, usually referring to what can be used as fuel.
The producers level usually has the most biomass