Unit A-Chapter 4-Lesson 1 Notes

How Do Organisms Interact?

Interactions Within Ecosystems

All living and nonliving parts of an ecosystem interact.

Some interactions are direct, such as when a person picks a peach from a peach tree and eats it.
Other interactions are indirect.  A honeybee and a person may have no direct interactions, but the honey bee might have pollinated the peach flower and so played a role in the production of the peach.

To survive in a particular ecosystem, organisms must be adapted to the environmental conditions of that ecosystem.

A healthy ecosystem is one which the living and nonliving parts are balanced.

Producers, Consumers, and Decomposers

Green plants are producers; using energy from the sunlight to make their own food through the process of photosynthesis. 

Organisms that cannot make their own food are called consumers.  Consumers may be herbivores, carnivores, or omnivores.

A herbivore is a consumer that eats only plants or other producers.

A carnivore is a consumer that eats only animals

An omnivore is a consumer that eats both producers and consumers.

A decomposer is an organism that obtains energy by consuming dead organisms and the wastes of living organisms.

In general, plants are producers, and animals are consumers.

However, one special producer is not a plant; its a type of bacteria that grows on the ocean floor.
This type of bacteria depend on sulfur-containing bacteria(sulfides) from deep ocean vents to release energy and make food.

Food Webs

Food chains describe how energy moves in an ecosystem from one organism to another.  

Green plants (producers) are the bottom link in a food chain.  Consumers make up the next links, followed by decomposers.

Different food chains combined form a food web.

Energy Pyramids

An energy pyramid is a model that shows how energy is used in a food chain or an ecosystem.

The amount of energy available to a certain group of organisms depends on which level of the energy pyramid it is on. 

Less energy is available at any level in the pyramid  than in the level below.  The top of the pyramid has the least amount of energy.