Ecology Explore the relationships among organisms and their interactions with the environment. Lesson 3

In this unit you will:

!  Explore the interdependent relationships among organisms and their environments.

!  Describe the cycling of matter and flow of energy within an ecosystem.

!  Learn that physical and biological changes to an ecosystem affect populations.

!  Evaluate design solutions for protecting an ecosystem.

The Flow of Energy Through Ecosystems

Energy in an ecosystem is passed from one organism to another through a series of interactions called a food chain. Food chains usually have three or four links. Energy decreases at each link.

Food Chain A food chain is a model used to show how energy

from food passes from one organism to another.

Producers are organisms that make their own foods.

Consumers are organisms that cannot make their own foods. Consumers eat producers and other consumers. An insect is an herbivore/consumer.

A mouse is an omnivore/consumer.

An owl is a carnivore/consumer.

A food chain shows the path of energy transferred from one living organism to the next in the chain. Food chains are usually only three to four links long.

Decomposers like bacteria, fungi, and parasites are necessary for all food chains.

The Food Chain of an Owl

Food Web A food web is a model used to describe a series of

overlapping food chains.

Ecological Pyramid is a model used to describe the transfer of energy through a community.

!  The energy pyramid, which is a type of ecological pyramid, models the decrease in transferred energy.

!  Most energy available in the biosphere comes from the sun.

!  Producers, like plants, capture and transform a small part of the sun’s energy.

!  When herbivores eat plants some of the energy is transferred to the herbivore, but most is released into the atmosphere as heat.

!  Energy is transferred at each link in the food chain, but decreases at each level. Heat…

Heat…

Heat…

Heat…

The Cycles of Matter !  Energy that is

scattered into the atmosphere at each level of the energy pyramid is renewed by the sun.

!  Physical organisms are made of matter.

!  Matter is never lost or gained; it is recycled!

!  Examples of materials that make up our bodies and cycle through ecosystems are: water, carbon and nitrogen.

Condensation Precipitation

Evaporation Transpiration Run off

Seepage

Root uptake

The Water Cycle

The Nitrogen Cycle is the transfer of nitrogen from the atmosphere to plants, and back to the atmosphere or directly into plants again. !  Nitrogen is important element needed by organisms to make

proteins.

!  Nitrogen gas makes up 78% of atmosphere but organisms cannot use it in this form.

!  Nitrogen fixation is the process of combining nitrogen in the air with other elements like ammonia or fertilizer, into a state plants can use for growth.

1. Organic wastes(from plants and animals) add nitrogen to the soil. 2. Bacteria in the soil convert the nitrogen into forms plants can use. 3. Plants use nitrogen in the soil to grow, develop, and produce seeds. 4. Plants are eaten by animals and people. The organic waste (which contains nitrogen) is returned to the soil again.

Simplified Nitrogen

Cycle

The Nitrogen Cycle N2 in atmosphere

NO3- & NO2

-

Nitrate & nitrite NH3 ammonia

Lesson 3 Review Vocabulary

food chain – a model used to show how energy from food passes from one organism to another. food web – a model used to describe a series of overlapping food chains. ecological pyramid – a model used to describe the transfer of energy through a community. water cycle – the continuous movement of water in the biosphere through evaporation, condensation, and precipitation.

nitrogen cycle – the continuous movement of nitrogen from the atmosphere to plants, and back to the atmosphere (or directly into plants) again.

Links to important info!

Food Chain game:

http://www.ecokids.ca/pub/eco_info/topics/frogs/chain_reaction/index.cfm

Energy Pyramid video:

https://www.youtube.com/watch?v=CReZd9OHEfs