The Biosphere

Chapter 3

What is ECOLOGY 1866 German Biologist Ernst Haeckel

first coined the term ecology. Came from the Greek word oikos

meaning “house” Defined today as the study of

interactions among living organisms and their environment

Energy Flow The sun is the main

source of energy for life on earth.

< 1 % of all sunlight that reaches earth is used by living organisms.

What happens to the rest?

Most is reflected off as heat energy.

Producers or Autotrophs Use sunlight or chemicals to make

their own food. Examples:

6CO2 + 6H2O C6H12O6 + 6O2

Performed on land by plants and in water by algae.

Can organisms make their own food without the aid of

sunlight? Chemosynthesis: using chemical

energy to make carbohydrates. Usually performed bacteria found in

harsh environments– Ocean vents, volcanoes, hot-acidic

Consumers or heterotrophs

Herbivores Carnivores Omnivores Detritivores Decomposers

Herbivores Carnivores Omnivores Detritivores Decomposers

Food Chains

te rt ia ry con su m er(la rg e fish )

secon d ary con su m er(sm all fish )

p rim ary con su m er(p lan k ton )

P rod u cer(a lg ae)

te rt ia ry con su m er(la rg e fish )

secon d ary con su m er(sm all fish )

p rim ary con su m er(p lan k ton )

P rod u cer(a lg ae)

Food Webs More complex than food chains A complex net of interactions among

organisms. (interdependence)

Trophic Levels Each location or step in a food chain or

food web represents a trophic level. Examples: producers, primary

consumers, secondary consumers, etc.

Ecological pyramids Only about ten

percent of the energy available within a trophic level is transferred to oragnisms at the next higher level.

Other pyramids: Biomass and numbers

Cycles of matter Unlike energy, matter is constantly

being recycled in an ecosystem. Known as biogeochemical cycles

Transpiration The release of water from the leaves

of plants. Water is exchanged through a plant’s

stomata. Evaporation is the second process that

releases water into the atmosphere.

Carbon Cycle

1. Biological processes (photosynthesis, respiration, decomposition)

2. Geochemical processes (volcanoes)

3. Biogeochemical (fossil fuels)

4. Human activity (factories, deforestation, car exhaust)

Nitrogen Cycle All organisms need nitrogen to live. Most abundant gas in atmosphere

(80%) Nitrogen gas is unusable for plants Must be “fixed” or changed into the

nitrate or nitrite form by bacteria in the soil. Known as nitrogen fixation

Phosphorus cycle P is important in the production of DNA

and RNA. Unlike water,oxygen, and nitrogen,

phosphorus is NOT found in the atmosphere. Found in rocks and minerals.

Nutrient Limitation When a single nutrient is scarce for a

particular ecosystem and limits the growth of organisms in that ecosystem.

Assignment: page 83-84 1-10, 12, 15, 16, 18, 22, 23, 29– Page 85 1-7