1. ECOLOGY UNIT
Chapters 20 & 21

2. Chapter 20 – Section 1
Science Standard – S7L4: Students will examine the dependence of organisms on one another and their environment.
c. Recognize that changes in environmental conditions can affect the survival of both individuals and entire species.

3. Key Vocabulary words – page 674b
Organism
Habitat
Biotic factor
Abiotic factor
Photosynthesis
Species
Population
Community
Ecosystem
Ecology

4. Living Things and the Environment
Organism – a living thing which obtains food, water, shelter, and other things it needs to live, grow, and reproduce from its environment.
An environment that provides the things the organism needs to live, grow, and reproduce is called its habitat.
Examples of habitats: forest, tropical rain forest, ocean floor, and tree trunks.

5. An organism interacts with both the living and nonliving parts of its habitat.
Biotic factors – living parts of a habitat; examples – grass, plants, hawks, eagles.
Abiotic factors – the nonliving parts of an organism’s habitat; examples – water, sunlight, oxygen, temperature, and soil.

6. Abiotic Factors
1.Water – all living things require water to carry out their life processes; makes up a large part of the bodies of most organisms; human bodies – 65% water; plants and algae need water with sunlight and carbon dioxide to make their own food by photosynthesis.
2.Sunlight – needed for photosynthesis

7. 3.Oxygen – most living things require oxygen to carry out their life processes.
4.Temperature – ones that are typical in an area determine the types of organisms that can live there.
5.Soil – a mixture of rock fragments, nutrients, air, water, and the decaying remains of living things;

8. Levels of Organization
1.Species – group of organisms that are physically similar and can mate with each other and produce offspring that can also mate and reproduce.
2.Population – made up of all the members of one species in a particular area.
3.Community – all the different populations that live close enough together in an area (a particular area contains more than one species of organisms) that interact by using the same resources (food, shelter).

9. 4.Ecosystem – made up of the community of organisms that live in a particular area along with their nonliving surroundings; Examples – prairie, mountain streams, oceans, forests.
Ecology is the study of how living things interact with each other and with their environment.
Ecologists – scientists who study ecology and how organisms react to changes in their environment.

10. Chapter 21 – Ecosystems and Biomes
Science Standard – S7L4: Students will examine the dependence of organisms on one another and their environment.
a. Demonstrate in a food web that matter is transferred from one organism to another and can recycle between organisms and their environment.
b. Explain in a food web that sunlight is the source of energy and that this energy move from organism to organism.

11. Key Vocabulary – page 710 B Producer Consumer Herbivore Carnivore
Omnivore Scavenger Decomposer
Food Chain Food Web Energy Pyramid
Water Cycle Evaporation Condensation
Precipitation Nitrogen Fixation Climate
Biogeography Continental Drift Dispersal
Exotic Species Biome Canopy Understory
Desert Grassland Savanna Deciduous tree
Coniferous Tree Tundra Permafrost Estuary Intertidal Zone Neritic Zone

12. Energy Flow in Ecosystems
Every organism has a role in the movement of energy through its ecosystem. This is necessary for the ecosystem to work.
An organism’s energy role is determined by how it obtains energy and how it interacts with other organisms.
Each of the organisms in an ecosystem fills the energy role of producer, consumer, or decomposer.

13. Producers Energy enters most ecosystems as sunlight.
Some organisms (plants, algae, and some bacteria) capture the energy of sunlight and store it as food energy.
These organisms use the sun’s energy to turn water and carbon dioxide into food molecules in a process called photosynthesis.
Are organisms that can make its own food – green plants and algae
Are the source for all of the food in an ecosystem.

14. Consumers
Are organisms that can not make their own food; obtains energy by feeding on other organisms.
Classified by what they eat:
herbivores – eat only plants; caterpillars
and deer
carnivores – eat only animals; lions and
spiders
omnivores – eat both plants and animals;
crows, bears, humans
scavenger – feeds on the bodies of dead
organisms; vultures and catfish

15. Decomposers
They break down wastes and dead organisms and return the raw materials to the ecosystem.
“nature’s recyclers”
While obtaining energy for their own needs, decomposers return simple molecules to the environment.
Examples – mushrooms and bacteria

16. Food Chains
Energy form the sun is transferred to each organism that eats a producer, and then to other organisms that feed on these consumers.
The movement of energy through an ecosystem can be shown in diagrams called food chains or food webs.
Food chains show only one path which energy can move through an ecosystem

18. Food Webs
Food webs consist of many overlapping food chains in an ecosystem.
An organism may play more than one role in an ecosystem.

20. Energy Pyramids
An energy pyramid diagram shows the amount of energy available at each level of a food web; that moves from one feeding level to another in a food web.
The most energy is available at the producer level of the pyramid.
As you move up the pyramid, each level has less energy available than the level below.
In general, only 10% of the energy at one level of a food web is transferred to the next higher level.
The other 90% of the energy is used for the organism’s life processes or is lost to the environment as heat.
As a result, there are usually few organisms at the highest level in a food web.

23. Cycles of Matter The supply of matter in an ecosystem is limited.
Matter in an ecosystem includes water, carbon, oxygen, nitrogen, and many other substances.
If matter can not be recycled, ecosystems will quickly run out of the raw materials necessary for life.

24. Water Cycle Earth’s water must be recycled.
Continuous process by which water moves from Earth’s surface to the atmosphere and back.
Three processes – evaporation, condensation, and precipitation – make up the water cycle.

26. Evaporation – process by which molecules of water absorb energy and change to a gas.
1.The energy for evaporation comes from the heat of the sun.
2. Plants release water vapor from their leaves; (Transpiration)
Animals release liquid water in wastes and water vapor when exhaling.

27. Condensation – process by which a gas changes to a liquid
1. As the water vapor rises higher in the atmosphere, it cools down.
2. The water droplets collect around particles of dust, eventually forming clouds.

28. Precipitation – rain, snow, sleet, or hail.
1. As more water vapor condenses, the drops of water in the cloud grow larger.
2. Eventually the heavy drops fall back to Earth as precipitation.
3. Some soaks into soils, some falls into other water sources.

30. Carbon and Oxygen Cycles
Carbon is necessary for living things.
Most organisms use oxygen for their life processes.
The carbon and oxygen cycles are linked.
Producers, consumers, and decomposers play roles in recycling carbon and oxygen.

31. The Carbon Cycle
Producers use carbon from the carbon dioxide to make food molecules.
Consumers eat producers and break down food molecules to obtain energy. They release carbon dioxide and water as waste.
Decomposers break down remains and return carbon compounds to the soil and carbon dioxide as a waste product.

33. The Oxygen Cycle Producers release oxygen through photosynthesis.
Most organisms take in oxygen from the air or water.

35. Human activities affect the levels of carbon and oxygen in the atmosphere.
When humans burn oil and other fuels, carbon dioxide is released onto the atmosphere.
When humans clear forests for lumber, fuel, and farmland, carbon dioxide levels also rise.

36. The Nitrogen Cycle
Nitrogen - necessary building block in living things.
Nitrogen moves from the air to the soil, into living things, and back into the air.
The air around us is 78% nitrogen gas, but living things can not use nitrogen gas (“free” nitrogen) because it is not combined with other kinds of atoms (not fixed).

37. Most organisms can use nitrogen only once it has been “fixed” or combined with other elements to form nitrogen-containing compounds – nitrogen fixation (performed by certain kinds of bacteria).
This bacteria live in nodules (bumps) on the roots of legumes – beans, peas, peanuts, alfalfa, clover which feed on the plant’s sugars.

38. Once the nitrogen has been fixed, producers can use it to build proteins and other complex compounds.
Nitrogen can cycle from the soil to producers and then to consumers many times; but bacteria break down the nitrogen compounds completely.
These bacteria then release free nitrogen back into the air which the cycle continues from there.