TEKS 5.9A Observe the Way Organisms Live and Survive in Their Ecosystem by Interacting

Name ______Class ______Date ______

TEKS 5.9A Observe the way organisms live and survive in their ecosystem by interacting with the living and non-living elements.
TEKS Lesson 5.9A:
Organisms and Ecosystems

Where do organisms live?

No matter where you go, you will find living things. Organisms exist on the highest mountain, the deepest ocean, the hottest desert, and the coldest ice sheet. From microscopic bacteria to the largest whales, a variety of living things cover Earth.

Organisms living throughout Earth all share its resources, such as water, air, and light. Living things depend on and are connected to each other through the resources they share. If something happens to one organism, other organisms can be affected too.

How is the living environment organized?

Many different kinds of animals, plants, and other organisms live all over Earth. These organisms interact with each other. They also interact with their environment. An organism’s environment is anything that can affect the organism.

An environment includes both living and nonliving parts. The living parts of the environment are organized into populations, communities, and ecosystems.

PopulationsA population is a group of individuals that belong to the same species and live in the same area. For example, all of the prairie dogs that live in a certain area make up a population. But all the other animals living there do not make up a population. That’s because they are members of different species.

Members of a population compete for resources in the environment. A population needs food, water, air, space, shelter and other resources. If resources become limited, individuals can die, and the population gets smaller.

1. IdentifySuppose a group of rabbits lives in a meadow. Another group of the same species of rabbits lives in a meadow five miles away. Are the two groups of rabbits part of the same population? Why or why not?

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CommunitiesIndividual populations do not live alone. Several different populations can live together and interact in an environment. A community is a group of populations that interact with one another in a particular area. Look at the figure above. The prairie dogs, grouse, owls, bison, rattlesnakes, grasses, and trees are part of the same community.

EcosystemsCommunities depend on the nonliving environment to meet many of their needs. These needs include food, water, shelter, and minerals. An ecosystem is a community of organisms living together along with the nonliving parts of the environment. An ecosystem can be as small as a crack in a sidewalk or as large as a forest. Every ecosystem interacts with other ecosystems.

The area or place where an organism lives in an ecosystem is called a habitat. You can think of a habitat as an organism’s address. The prairie dogs’ habitat is grassland on the Great Plains of North America.

2. ExplainHow is a population different from a community?

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How do organisms interact in ecosystems?

The organisms in a community differ in many ways. But they all depend on the living and nonliving parts of their ecosystem to live and survive.

Nonliving Parts of EcosystemsLiving things must interact with the nonliving parts of an ecosystem to live and survive. Water, sunlight, air, temperature, and soil are some of the nonliving parts of an ecosystem. These conditions often must be within a certain range for an organism to survive and live from day to day. For example, if an organism gets too little water, it may die.

•WaterAll living things need some water to survive. That’s because many chemical processes that take place in organisms need water. The amount of water in an ecosystem can limit the number of organisms it can support. If there isn’t enough water for all the organisms in an ecosystem, some will die.

•SunlightBecause plants need sunlight to make food, sunlight is important to all living things. Most organisms that cannot make their own food depend directly or indirectly on plants. The amount of sunlight an area receives determines the kinds of plants that grow there. That, in turn, determines the other organisms that live there.

•AirMost organisms need air as a source of oxygen. Your own body cannot survive without oxygen for more than a few minutes. Organisms that live in water, such as fish, use oxygen that is dissolved in the water. Plants need oxygen, too. And they need another gas found in air, carbon dioxide, to carry on the process of making food.

•TemperatureThe temperature of an area also helps determine which organisms live there. Each organism can live only in a particular temperature range. Your body would not survive long without protection in freezing temperatures. But the polar bear is at home in those temperatures.

•SoilThe soil in an area influences the kinds of plants and animals that can live there. Soil is made up of rock pieces, air, water, and the decaying remains of organisms. Soil contains water and other substances that plants need in order to survive and grow. Soil provides a home for many animals, including prairie dogs.

3. SummarizeHow do living things interact with water, air, and soil?

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Living Parts of EcosystemsLiving things interact with all the other living things around them. How organisms interact with other living things determines whether the organism will survive.

Look again at the illustration. The prairie dogs interact with members of their own species. The prairie dogs also interact with many other living things. They interact with the plants whose seeds and berries they eat. They compete with animals that use the same plants for food. And they interact with owls and rattlesnakes that eat prairie dogs. They also interact with organisms that are too tiny to be seen. These include the billions of bacteria that live in the soil.

These interactions affect whether the prairie dogs survive. If other animals eat the prairie dogs’ food, the prairie dog population will fall. Owls can catch prairie dogs that are slow to react. Bacteria or other organisms that cause disease also reduce the prairie dogs’ ability to survive.

Lesson Check

1.ReviewWhat makes up an organism’s environment?

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2.IdentifyWhat term describes both the organisms that live in an environment and the nonliving parts of the environment?

AcommunityBecosystem

CspeciesDpopulation

3.ObserveLook at the illustration of the prairie dog town.

a.How do prairie dogs live and survive by interacting with the nonliving parts of their ecosystem?

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b.How do prairie dogs live and survive by interacting with the living parts of their ecosystem?

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