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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