1. Environmental Science
Chapter 5 Lecture Notes
“How Ecosystems Work”

2. Chapter 5 Targets
I can explain how photosynthesis and cellular respiration are related.
2. I can explain the difference between autotrophs and heterotrophs and list examples of each.
3. I can explain the difference between a food chain and a food web
4. I can diagram a food chain with at least four members and label the trophic level for each member.
5. I can explain the 10% Rule using an energy pyramid

3. Life Depends on the Sun Burning the Fuel
Energy from sun enters ecosystem when plants use sunlight to make sugar molecules.
Photosynthesis: process where plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen.
Burning the Fuel
Cellular Respiration: process when cells use energy from carbohydrates; oxygen combines with glucose to form water and carbon dioxide.
Cellular respiration occurs inside cells of most organisms.

4. From Producers to Consumers
Producer: organism that can make organic molecules from inorganic molecules.
also called autotrophs (make their own food)
Consumer: organism that eats other organisms or organic matter instead of producing its own nutrients.
also called heterotrophs
Exception to the Rule (or what is common)
Deep-ocean communities of worms, clams, crabs, mussels, and barnacles, live in total darkness on ocean floor, where photosynthesis cannot occur.
Producers are bacteria that use hydrogen sulfide in water (not typical, usually use sun)
Other organisms eat the bacteria

5. What Eats What? Trophic Levels Types of Consumers: Herbivores
Carnivores
Omnivores
Decomposers T2

6. Food Chains & Food Webs
Food chain: sequence in which energy is transferred from one organism to the next
Food web: shows many feeding relationships possible in an ecosystem. T3

7. Trophic Levels
Trophic level: one of the steps in a food chain or food pyramid.
Examples include:
Producers
Primary consumers
Secondary consumers
Tertiary consumers
*On the food web, label the trophic levels… T4

8. Comprehension Check On the food web, label the following:
-Producers (Autotrophs)
-Carnivores
-Herbivores
-Omnivores
-1st Order Consumers
-2nd Order Consumers
-3rd Order Consumers
-4th Order Consumers
Leaves, Berries
fox, frog, owl snake
Grasshopper, squirrel, rabbit
4th
3rd
Mouse
2nd
3rd
2nd
3rd
Mouse, grasshopper, rabbit, squirrel
Fox, mouse, frog, snake
Owl, fox, snake
1st
Owl
2nd
2nd
1st
1st
1st
producer
producer

9. Trip to Neptune
The crew of a space shuttle bound for Neptune is able to grow wheat and corn in its spacecraft. Would they be able to support more crew members by (choose one answer below):
Eating the corn and wheat
Feeding the corn and wheat to chickens, then eating the chickens
3. Feeding the corn and wheat to chickens, then eating the chickens’ eggs

10. Trophic Levels Each time energy is transferred, some is lost as heat.
Less energy is available to organisms at higher trophic levels. One way to visualize this is with an energy pyramid.
Energy loss limits number of trophic levels in an ecosystem
10% Rule T5

12. Trip to Neptune
The crew of a space shuttle bound for Neptune is able to grow wheat and corn in its spacecraft. Would they be able to support more crew members by (choose one answer below):
Eating the corn and wheat 
Feeding the corn and wheat to chickens, then eating the chickens
3. Feeding the corn and wheat to chickens, then eating the chickens’ eggs

13. Comprehension Check
How does energy move through most ecosystems on Earth?
From the sun to consumers to producers
From the sun to producers to consumers to decomposers
From the sun to decomposers to producers to consumers
From the sun to consumers to producers back to consumers

14. Comprehension Check
How does energy move through most ecosystems on Earth?
From the sun to consumers to producers
From the sun to producers to consumers to decomposers
From the sun to decomposers to producers to consumers
From the sun to consumers to producers back to consumers

15. Comprehension Check
Which of the following statements indicates an understanding of the importance of energy to life on Earth?
Many organisms on Earth require energy for their life processes.
All organisms on Earth require energy for their life processes.
Energy is required for the most important life processes on Earth.
The most important organisms on Earth require energy for their life processes.

16. Comprehension Check
Which of the following statements indicates an understanding of the importance of energy to life on Earth?
Many organisms on Earth require energy for their life processes.
All organisms on Earth require energy for their life processes.
Energy is required for the most important life processes on Earth.
The most important organisms on Earth require energy for their life processes.

17. Chapter 5 Targets
6. I can list and describe the three stages of the carbon cycle.
7. I can identify two ways humans are affecting the carbon cycle.
8. I can list the three stages of the nitrogen cycle.
9. I can describe the role that nitrogen-fixing bacteria and decomposers play in the nitrogen cycle.
10. I can list the stages of the phosphorus cycle.
11. I can explain how the excess use of fertilizer can affect the nitrogen and phosphorus cycles.

18. The Carbon Cycle
Carbon cycle: movement of carbon from abiotic environment into living things and back
Carbon: main component of proteins, fats, and carbohydrates, which make up all organisms. T6

19. How Humans Affect the Carbon Cycle
Humans burn fossil fuels, releasing carbon into atmosphere.
2. Humans destroy forests, preventing uptake of CO2 through photosynthesis
Increased levels of CO2 contribute to global warming.
Remember the difference between global warming and the greenhouse effect! T7

21. Comprehension Check
What is the process that breaks down food to yield energy called?
A. cellular digestion
B. cellular respiration
C. decomposition
D. photosynthesis

22. Comprehension Check
What is the process that breaks down food to yield energy called?
A. cellular digestion
B. cellular respiration
C. decomposition
D. photosynthesis

23. The Nitrogen Cycle
Nitrogen cycle: process when nitrogen circulates between air, soil, water, plants, and animals in an ecosystem.
All organisms need nitrogen to build proteins
Nitrogen makes up what % of air we breathe?      T8

24. Fixing Nitrogen Nitrogen must be fixed before organisms can use it.
Nitrogen-fixing bacteria convert atmospheric nitrogen into useable nitrogen.
The bacteria live within roots of plants called legumes; which include beans, peas, and clover.
The bacteria use sugar provided by legumes to produce nitrogen compounds such as nitrates.
Excess nitrogen fixed by bacteria is released into soil. T9

25. Decomposers and the Nitrogen Cycle
Nitrogen stored in bodies of living things is returned to nitrogen cycle once they die.
Decomposers break down decaying plants and animals and their wastes.
After decomposers return nitrogen to soil, bacteria transform small amounts of the nitrogen into nitrogen gas, which returns to atmosphere to complete nitrogen cycle. T9

27. The Phosphorus Cycle
Phosphorus makes up many molecules in the cells of organisms.
Plants get phosphorus from soil and water
Animals get phosphorus by eating plants or other animals that have eaten plants.
Phosphorus cycle: cyclic movement of phosphorus in different chemical forms from environment to organisms and back to environment.    
T10

28. Fertilizers and the Nitrogen and Phosphorus Cycles
Fertilizers contain both nitrogen (N) and phosphorus (P)
Excess fertilizer can enter land and aquatic ecosystems through runoff.
Excess N and P cause rapid growth of algae
Excess algae deplete aquatic ecosystems of nutrients such as oxygen, which fish and other aquatic organisms need
T11

29. Comprehension Check
What role do bacteria play during the nitrogen cycle?
A. Bacteria store nitrogen in wastes.
B. Bacteria convert nitrogen into water.
C. Bacteria turn nitrogen into phosphates.
D. Bacteria transform nitrogen into molecules.

30. Comprehension Check
What role do bacteria play during the nitrogen cycle?
A. Bacteria store nitrogen in wastes.
B. Bacteria convert nitrogen into water.
C. Bacteria turn nitrogen into phosphates.
D. Bacteria transform nitrogen into molecules.

31. Chapter 5 Targets
12. I can define and list two examples of ecological succession.
13. I can explain how a pioneer species contributes to ecological succession.
14. I can describe how lichens contribute to primary succession.

32. Ecological Succession
Ecosystems are constantly changing.
Ecological succession: gradual process of change and replacement of types of species in a community.
Each new community often makes it harder for the previous community to survive.
T12

33. Primary Succession
Primary succession: begins in area that previously did not support life
Rocks
Cliffs
Sand dunes
Volcanic eruptions
First species to colonize bare rock will probably be bacteria and lichens, which can live without soil.
growth of lichens breaks down rock, which with the action of water, begins to form soil.
T13/T14

35. Secondary Succession
Secondary succession occurs where an ecosystem previously existed.
One community replaces another that has been partially or totally destroyed.
Can occur in ecosystems that have been disturbed by humans, animals, or natural processes such as storms, floods, fires or earthquakes.
T12

36. Ecological Succession
Pioneer species: species that colonizes uninhabited area and starts ecological cycle for other species.
Lichens
Bacteria
Climax community: final, stable community in equilibrium with environment.
Even though a climax community may change in small ways, this type of community may remain the same through time if not disturbed.
T12

37. Ecological Succession
T12

38. Comprehension Check
Which of the following shows an effect on the carbon cycle of the increased burning of fossil fuels?
More carbonates remain in fossil fuels.
More carbon dioxide is absorbed by organisms.
More carbon dioxide is absorbed by the atmosphere.
More carbohydrates remain buried deep in the ground.

39. Comprehension Check
Which of the following shows an effect on the carbon cycle of the increased burning of fossil fuels?
More carbonates remain in fossil fuels.
More carbon dioxide is absorbed by organisms.
More carbon dioxide is absorbed by the atmosphere.
More carbohydrates remain buried deep in the ground.