Lesson 4



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Living things in an environment are part of an ecosystem. In an ecosystem, living and nonliving things interact in an environment. The nonliving part of an ecosystem includes water, rocks, air, light, and soil. The living part of an ecosystem includes plants and animals.

The study of how living and nonliving things interact is called ecology. The living part of an ecosystem forms a community. Communities can be divided into different populations. A population is made of one type of organism. Each organism’s home is called its habitat. An earthworm lives in a soil habitat. A whale’s habitat is the ocean.

What makes one ecosystem different from another? In many cases, water is the key. A desert is dry. A rain forest has plenty of water. Another resource that can affect an ecosystem is sunlight. Some plants, such as cacti, grow where there is little water but plenty of sunlight. Still another resource is soil. Areas with soil that has many nutrients can support many plants. Few plants grow in areas with soil that does not have many nutrients.

A community works like a team. Each member of the team has its own job to do. There are three different types of members. Producers make food. You can tell producers by their green color. To make food, producers use water, air, simple chemicals, and the Sun’s energy.

A food chain is the steps in which organisms get the food to survive. Producers, consumers, and decomposers are the three types of organisms that play a role in the community. They are also involved in the food chain.

Consumers use the food that producers make. Consumers include animals and some one-celled organisms. There are consumers that eat plants. Other consumers eat only animals. A third type of consumer eats both plants and animals.

Decomposers break down the wastes and the remains of other organisms. Decomposers include bacteria and some fungi. They also include larger organisms, such as worms and snails. Decomposers can spoil the food we eat. We can freeze, dry, and can foods to prevent spoilage.

An ecosystem is made up of many parts. When the parts don’t work together, the ecosystem is disturbed. It is important to understand how living and nonliving parts depend on one another.

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