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Upper Elementary Intermediate Secondary

Population, Biological Communities, and Ecosystems

Populations and communities are groups of organisms.

- A population is a group of the same species living in the same area.
- A community is a group of different species living in the same area.

An ecosystem is all of the organisms in an area plus the nonliving beings in the environment.

Ecosystems

Ecosystems are characterized by:

Types and quantities of available energy sources, such as chemical energy in plants.
Types and characteristics of energy flows, such as food chains and food webs.
An ability to use energy to maintain a balanced or steady state.
The amount of energy available with respect to the amount of energy used by an ecosystem. This is called an ecosystem's energy budget.
The total energy budget of an ecosystem determines how many living beings it can support. This is called its carrying capacity.

Living Systems

Energy flow in living systems enables humans and other living beings to survive.

Living systems use energy to grow, change, maintain health, move, and reproduce. Examples include:

Plants converting solar energy to chemical energy via photosynthesis
Animals converting chemical energy in plants or in other animals to chemical energy

Living systems, whether a single animal or a whole ecosystem, differ in how fast they use energy.

Some living systems, such as birds, use energy quickly for growth and metabolism and must replace it quickly.
Others, such as turtles, use energy more slowly and need to replace it less frequently.
Energy cycles faster through a rainforest than through colder, drier areas like tundra ecosystems.

Nonliving Systems

Energy flow through nonliving systems creates weather patterns and shapes the Earth’s surface.

Some examples include:

Energy from the sun warms the Earth unevenly, driving weather systems and ocean currents.
Thermal energy that is in Earth’s interior shapes and moves Earth’s crust, giving way to volcanoes, earthquakes, and over time, mountains.
The movement of water in all of its forms can erode landscapes, flood coastlines and riverbanks, and scrape mountains flat.

Energy in Human Societies

Humans have used energy to shape their lives throughout the 300,000 years we have been on Earth. Over time, we have used more and more complex forms of energy as societies gathered in more and more intricate systems.

The growth of human populations and the desire to improve their quality of life drove human energy transitions in history. These transitions grew more complex and used a greater diversity of types of energy, and the effects of their use on Earth’s natural systems also grew in both intensity and complexity.

Instead of humans adapting to the environment in which they live, they transitioned to controlling it – which required greater amounts of energy and greater environmental impacts.

Energy transitions in history include:

Human metabolism & fire
Domestication of draft animals & use of fire for producing wood and metal tools
Evolution of engines & burning of fossil fuels
Electrification & transition back to renewable energies

We are currently living in a world that needs to improve energy efficiency, shift to sustainable energy sources, and work towards equitable distribution of energy resources with the goal of decreasing our impact on global ecosystems. Without this transition, we threaten the biosphere on which we all depend.

Teaching Resources from KEEP

Not sure how you would teach these concepts in your classroom? Check out these activities, lessons, and kits from KEEP:

Energy in an Ecosystem - Students survey different environments and investigate how sunlight, soil, moisture, temperature, and wind affect
living elements in an ecosystem.
Photosynthesis Promenade and Food Chain Game - By participating in physical activities, students will simulate the process of photosynthesis and transfer of energy between organisms.
Discovering Energy in Nature Kit - Resources for educators to take students outdoors to explore energy in nature concepts