The BiosphereChapter 3

Dr. Donna HowellBiology IBlacksburg High School

Ecology

Ecology is the study of interactions among organisms and between organisms and their environment.

The biosphere contains the combined portions of the planet in which all life exists, and includes land, water and air.

Levels of Organization

Organisms in the biosphere range in complexity from a single individual to an entire biosphere.

Energy Flow

• Sunlight is the main energy source for all life on Earth.• There are two types

of organisms with regards to how they get their energy:• Autotrophs – can

produce their own food from the Sun• Heterotrophs –

cannot produce their own food from the Sun

Autotrophs

• Some autotrophs get their energy through the process of photosynthesis, getting their energy from the Sun.• Other autotrophs

get their energy through the process of chemosynthesis, getting their energy from chemical bonds of inorganic molecules.

Consumers

• Another name for heterotrophs is consumers.• There are different

types of consumers:• Herbivores – obtain

energy by eating plants

• Carnivores – obtain energy by eating animals

• Omnivores – obtain energy from both plants and animals

• Detritivores – obtain energy from dead plant and animal matter

Consumers

• Another important group of heterotrophs, or consumers, are the decomposers.• These organisms

break down organic matter, and contribute to the “circle of life.”• Examples are

bacteria and fungi.

Feeding Relationships

• Energy flows through an ecosystem in one directions, beginning with the Sun.• Then goes to

producers, and then to consumers.

Food Chains

• A food chain is a series of steps showing energy flow among organisms.

Food Webs

• A food web shows all of the food chains in an ecosystem, and links them together into a series of feeding relationships.

Trophic Levels

• Each step in a food chain or food web is called a trophic level.• Producers make up

the first trophic level.• Primary, secondary,

and tertiary consumers make up all other levels. • Each consumer

depends on the trophic level below it for its energy.

Ecological Pyramids

• The amount of energy or matter in an ecosystem can be represented by an ecological pyramid. • An ecological

pyramid is a diagram that shows the relative amounts of energy or matter within each tropic level.

Ecological Pyramids

• Three types of ecological pyramids:

• Energy pyramids• Biomass

pyramids• Pyramid of

numbers

Energy Pyramid

• This pyramid shows that only about 10 percent of the energy available within one trophic level is transferred to organisms at the next trophic level.

Biomass Pyramid

• This pyramid shows the total amount of living tissue within a given trophic level.• Expressed in terms

of grams of organic matter per unit area.• Represents the

amount of potential food available for each trophic level in an ecosystem.

Pyramid of Numbers

• This pyramid is based on the n umbers of individual organisms at each trophic level.

Cycles of Matter

• Unlike the one-way flow of energy in an ecosystem, matter is recycled within and between ecosystems.• These cycles are

biogeochemical cycles.

Water Cycle

Carbon Cycle

Nitrogen Cycle

Phosphorus Cycle

The End!