Chapter 4 - Ecosystems

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Case Study - What's to blame for the bloom?

Autotrophs (Primary Producers) - use photosynthesis to capture energy from the sun; some bacteria use chemosynthesis


photosynthesis equation

Glucose (sugar) is used for energy to grow and maintain life

Heterotrophs (Consumers) - gain energy by eating other organisms

4.2 Energy Flow in Ecosystems

Food chain - shows hopw energy moves in an ecosystem

Food web - contains many chains showing interactions

- What eats a large mouth bass?
- What does the bass eat?
- Which animal is an omnivore?
- Does this web represent all the organisms in the lake?

Ecological Pyramids - models that show amount of energy or matter at each level in a chain

Trophic level - a step in the food chain

ecological pyramid

Primary Consumers - eat plants
Secondary Consumers - eat primary consumers

Energy is lost as heat as you move up the chain. An ecosystem can support more primary consumers, that secondary consumers. *This is why in a prairie, there will be many mouse, but only a few hawks.

Pyramid of numbers - displays the number of individuals at each trophic level (generally more herbivores than carnivores)

Sometimes the pyramid is inverted. Example, ONE tree might support several primary consumers.

pyramid of numbers

Pyramid of Biomass - shows the weight at each level; plants have more mass than animals

4.3 Cycles of Matter

Biogeochemical cycles - matter is reused in a system

Water Cycle - (condensation, precipitation, transpiration, evaporation

Carbon Cycle - carbon enters the atmosphere from animal waste, decomposition, and burning fossil fuels

Nitrogen Cycle - 78% of the air is nitrogen; N is converted to useable forms by bacteria

Classroom Activities and Resources

Interpreting a Food Web

Analyzing Graphics - Carbon Cycle

Nitrogen Cycle Worksheet

CK 12 - Nitrogen Cycle

Case Study - Coyote Removal

Chapter 4 Reading Guide