Unit: Ecosystems – Guided Notes
3e. Explain energy flow in a specified ecosystem. (DOK 2)

Populations, communities, and habitats

Niches, ecosystems and biomes

Producers, consumers and decomposers in an ecosystem
4d. Research the importance of the conservation of renewable and nonrenewable resources, including (but not
limited to) Mississippi, and justify methods that might be useful in decreasing the human impact on global
warming. (DOK 3)

Relationships of the cycles of water, carbon, oxygen, and nitrogen
Key Terms: Producer, Consumer, Herbivore, Carnivore, Omnivore, Scavenger, Decomposer, Food chain,
Food web, Energy Pyramid, Ecosystem, Niche, Biome, Population, Community, Habitat, Nitrogen Cycle,
Water Cycle, Carbon Cycle, Oxygen Cycle
I. Energy Flow in Ecosystems
A. Energy Roles
Key Concept: Each of the organisms in an ecosystem fills the energy role of producer, consumer, or
decomposer.
• Energy enters most ecosystems as ___________________.
• Energy moves through an ecosystem. Each organism in an ecosystem plays a part in the movement of energy.
• An organism that can make its own food is called a_____________________-.
• An organism that gets energy by eating other organisms is called a consumer. Herbivores are consumers that
eat only ____________________. Carnivores are consumers that eat only __________________. Omnivores
are consumers that ______________ __________________ plants and animals.
• An organism that gets energy by eating wastes and_____________ organisms is called a decomposer.
Mushrooms and bacteria are decomposers
B. Food Chains and Food Webs
Key Concept:The movement of energy through an ecosystem can be shown in diagrams called food chains
and food webs.
• Food chains and food webs are diagrams. They show how _______________ moves through an ecosystem.
• A _______________ _________________- shows a series of organisms that eat other organisms.
• The first organism in a food chain is always a ____________________. The organism that eats the producer is
called a firstlevel consumer. The organism that eats the first-level consumer is called a second-level consumer.
• A food __________________ is made up of many food chains in an ecosystem. The food chains overlap and
connect with one another.
C. Energy Pyramids
Key Concept: In an energy pyramid, 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.
• An energy ____________________ is a diagram in the shape of a pyramid. It shows how much energy moves
from one
feeding level to another. Energy moves from the bottom level up to the top level.
• The first level of an energy pyramid always has the most energy.
• Each level of an energy pyramid has ______________ energy than the level below it.
II. Cycles of Matter
A. The Water Cycle
Key Concept: The processes of evaporation, condensation, and precipitation make up the water cycle.
• Matter _________________ over and over through ecosystems. Cycles of matter include the water cycle, the
carbon and oxygen cycles, and the nitrogen cycle.
• ________________ moves from Earth’s surface to the air and back again through the water cycle.
• Evaporation is when a liquid changes into a _____________. In the water cycle, liquid water evaporates from
oceans, lakes, and other bodies of water. The liquid water evaporates to form water vapor, a gas, in the
atmosphere.
• _______________________- is when a gas changes into a liquid. In the water cycle, water vapor condenses in
the atmosphere into water droplets. The water droplets then collect into clouds.
• In the water cycle, the droplets of water in clouds _____________ back to Earth as precipitation.
Precipitation includes rain, snow, sleet, and hail.
B. The Carbon and Oxygen Cycles
Key Concept: In ecosystems, the processes by which carbon and oxygen are recycled are linked.
Producers, consumers, and decomposers play roles in recycling carbon and oxygen.
• ________________ things need both carbon and oxygen to live.
• In ecosystems, the carbon cycle and the oxygen cycle are closely linked together.
• In the carbon cycle, producers take in _________________ from the air to use in photosynthesis. Producers,
consumers, and decomposers all release carbon dioxide back into the air as a waste product.
• In the oxygen cycle, most organisms take in oxygen from the air to carry out ________________ processes.
Producers release oxygen into the air as a waste product of photosynthesis.
C. The Nitrogen Cycle
Key Concept: In the nitrogen cycle, nitrogen moves from the air to the soil, into living things, and back
into the air.
• Air is about 98 percent ________________ gas.
• Most organisms can use nitrogen only after it has been _____________________. Fixing nitrogen means
combining it with other
substances.
• Certain kinds of ________________ carry out nitrogen fixation. Nitrogen fixation is the process of
combining nitrogen with other substances. Once nitrogen fixation occurs, organisms can use nitrogen to make
compounds in their cells.
•_________________ break apart dead organisms and animal wastes. This adds nitrogen compounds to the
soil. In soil, certain bacteria break down nitrogen compounds and release nitrogen gas into the air.