1. Aim: How does energy flow in an ecosystem? Look at the pond ecosystem
We know all living things need energy in order to survive. But…….
Where does the energy to support life originally come from?
Which type of living things can trap this energy?

2. These are some interesting questions we can ask ourselves.
How does energy flow in an ecosystem?
Does all the energy get transferred or some of it is loss?
These are some interesting questions we can ask ourselves.

3. Flow of Matter and Energy in Ecosystems
Review
Food chains: the stepwise flow of energy and nutrients through an ecosystem.
from plants (producers)
to herbivores (primary consumers)
to carnivores (secondary and higher-level consumers
berries → mice → black bear

4. Food chains Feeding relationships
all food chains start with energy from the sun
first level of all food chains is plants
most food chains usually go up only 4 or 5 levels
all levels connect to decomposers
Tertiary consumer
Top carnivore
Sun
Level 4
Secondary consumer
Carnivore
Level 3
Primary consumer
Level 2
Herbivore
Level 1
Producer
Bacteria
Decomposers
Fungi

5. energy lost to daily living
Loss of Energy
Loss of energy between levels of food chain
To where is the energy lost? The cost of living!
17%
growth
energy lost to daily living
only this energy moves on to the next level in the food chain
33%
cellular
respiration
50%
waste (feces)

6. Trophic levels represent links in the chain
Each organism in a food chain represents a feeding step, or trophic level, in the passage of energy and materials.

7. Trophic
Levels

8. In this food chain, what is the producer?
What is the first level consumer?
What is the second level consumer?
Is the hawk the 3rd level consumer? Explain.

9. Review: Food Webs network of interconnecting food chains
It is a more realistic view of the trophic structure of an ecosystem than a food chain

10. Energy and trophic levels: Ecological pyramids
show how energy flows through an ecosystem.
illustrates that the amount of available energy decreases at each succeeding trophic level.
The total energy transfer from one trophic level to the next is only about ten percent

11. But what about nutrients?
Energy flows through but nutrients cycle
nutrients must be recycled to be available for the next generation
decomposers return nutrients to the soil after creatures die
fungi
bacteria
decomposers

12. Energy flows Nutrients cycle
sun
producers (plants)
primary consumers
(herbivores)
secondary consumers
(carnivores)
decomposers
loss of energy
loss of energy
loss of energy
soil
soil

13. Ecosystem inputs nutrients cycle inputs energy nutrients biosphere
energy flows through
constant input of energy
nutrients cycle
Matter cannot
be created or destroyed
Don’t forget the laws of Physics!
nutrients can only cycle
inputs
energy
nutrients

14. Energy Pyramid A B C D level D = producers level C = primary consumers
level B= secondary consumers
level A = tertiary consumers
tertiary consumers A
secondary consumers B
primary consumers C
producers D

15. Energy Pyramid
What happens to the total amount of available energy as you move up the trophic level?
tertiary consumers A
secondary consumers B
primary consumers C
producers D

16. Energy Pyramid
Which trophic level contains the most amount of available energy?
Which trophic level contains the least amount of available energy?

17. Summary Question
How does energy flow in an ecosystem?

18. Critical Thinking Question
What happens to an ecosystem if there is a drought (prolong period without rain) ? Explain. Must be as least 1 paragraph.

19. Critical Thinking-Application Question
As the number of people in poor countries begin to become wealthy, they start to demand and consume more meat based diet. How will this effect the environment and you?

20. Let’s Check for Understanding Regents Based Questions
Base your answer to the question on the diagram below and on your knowledge of biology.
What is an appropriate title for this diagram?
Energy Flow in a Community
Ecological Succession
Biological Evolution
A Food Chain

21. Let’s Check for Understanding Regents Based Questions
2. One arctic food chain consists of polar bears, fish, seaweed, and seals. Which sequence demonstrates the correct flow of energy between these organisms?
seals → seaweed → fish → polar bears
fish → seaweed → polar bears → seals
seaweed → fish → seals → polar bears
polar bears → fish → seals → seaweed

22. Let’s Check for Understanding Regents Based Questions
The diagram below shows a food chain.
3. If the population of bobcats decreases, what will most likely be the long-term effect on the rabbit population?
It will increase, only.
It will decrease, only.
It will increase then decrease.
It will decrease then increase.

23. Let’s Check for Understanding Regents Based Questions
4. Which sequence shows a correct pathway for the flow of energy in a food chain?
bacteria – grass – fox – owl
grass – grasshopper – frog – snake
fungi – beetle – algae – mouse
algae – snake – duck – deer

24. Let’s Check for Understanding Regents Based Questions
Base your answer to the question on the diagram of a food web and on your knowledge of biology.
5. If the population of mice is reduced by disease, which change will most likely occur in the food web?
The cricket population will increase.
The snake population will increase.
The grasses will decrease.
The deer population will decrease.

25. Let’s Check for Understanding Regents Based Questions
Base your answer to the question on the diagram of a food web and on your knowledge of biology.
6. What is the original source of energy for this food web?
chemical bonds in sugar molecules
enzymatic reactions
the Sun
chemical reactions of bacteria