u nit 8: e cology keystone review. u nit 8: e cology describe the levels of ecological organization...
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UNIT 8: ECOLOGYKEYSTONE REVIEW
UNIT 8: ECOLOGY
Describe the levels of ecological organization (from small to big) Organism: A form of life; an animal, plant, fungus,
protist or bacterium. Population: A group of individuals of the same species
living in a specific geographical area and reproducing. Community: Different populations of organisms
interacting in a shared environment. Ecosystem: A system composed of organisms and
nonliving components of an environment. Biome: A large area or geographical region with distinct
plant and animal groups adapted to that environment. Biosphere: The zone of life on Earth; sum total of all
ecosystems on Earth.
UNIT 8: ECOLOGY
Describe characteristic biotic and abiotic components of aquatic and terrestrial ecosystems Abiotic: A term that describes a nonliving factor in an
ecosystem. Abiotic factors determine the plants and vegetation.
Biotic: A term that describes a living or once‐living organism in an ecosystem.
Aquatic (water ecosystem) Biotic: all living things Abiotic: water, temperature, pH, water movement, salinity,
dissolved oxygen etc. Terrestrial (land ecosystem)
Biotic: all living things. Abiotic: temperature, rainfall, wind, fires, elevation, land, etc.
UNIT 8: ECOLOGY
Describe how energy flows through an ecosystem Energy is not created or destroyed. Energy can be transferred.
Every time energy is transferred some is lost as heat. To trace the flow of energy start from bottom to
top. Producers are at the base. Primary consumers (herbivores) are next. Secondary consumers (carnivores) are next. Tertiary consumers (top level).
UNIT 8: ECOLOGY
Describe how energy flows through an ecosystem Food chains: A simplified path illustrating the
passing of potential chemical energy (food) from one organism to another organism.
Food webs: A complex arrangement of interrelated food chains illustrating the flow of energy between interdependent organisms.
Energy pyramids: A model that illustrates the biomass productivity at multiple trophic levels in a given ecosystem.
UNIT 8: ECOLOGY
Describe biotic interactions in an ecosystem Symbiosis: a relationship between two
organisms. Mutualism: both organisms benefit. (ex. Flowers and
insects) Parasitism: one organism benefits and the other is
harmed. (Ex. Humans and a tapeworm). Commensalism: one organism benefits and the other
does not benefit or is not harmed. (ex. Shark and remora)
UNIT 8: ECOLOGY
Competition: When individuals or groups of organisms compete for similar resources such as territory, mates, water, and food in the same environment. Both organisms lose out since there are limited resources. Predator-prey relationship: The populations of
predators and prey follow each other in a cycle like so:
Prey
Predator
UNIT 8: ECOLOGY
Describe how matter recycles through an ecosystem Water cycle: most water is in the oceans. Evaporation
moves it into the atmosphere and sometimes onto land. It is powered by the sun.
Carbon cycle: carbon dioxide is absorbed by plants and forms organic molecules through photosynthesis. Cellular respiration releases it back into the atmosphere.
Oxygen cycle: there is a fast exchange of oxygen between living things and the atmosphere. There is a slow exchange between living things rocks and soil.
Nitrogen cycle: huge amounts of nitrogen are in the atmosphere. Most organisms can’t use atmospheric nitrogen. Some bacteria have to “fix” the nitrogen and make it available in the food web.
UNIT 8: ECOLOGY Describe how ecosystems change in response to
natural and human disturbances Stable ecosystems may change very slowly. Disturbances can
cause drastic changes. Disturbances can be natural (fire, pioneer species, disease,
natural weather anomalies, and population fluctuations). Humans can cause many disturbances (fire, introduced species, climate change, and pollution). Climate changes: humans have introduced excess greenhouse gasses
(water vapor, carbon dioxide, methane, nitrous oxide, and ozone) into the atmosphere. It appears to be trapping more heat in our atmosphere. It is affecting ecosystems through climate fluctuations and ocean levels.
Introduction of nonnative species: A species normally living outside a distribution range that has been introduced through either deliberate or accidental human activity; also can be known as introduced, invasive, alien, nonindigenous, or exotic. Sometimes organisms that are brought into a new ecosystem are too
successful and displace native organisms. This can lead to the native species dying out.
UNIT 8: ECOLOGY
Describe how ecosystems change in response to natural and human disturbancesPollution: air, water, light, thermal, noise
SOME CHEMICALS MAY ACT AS POLLUTANTS IF THEY:-trap heat in the atmosphere causing the greenhouse effect.-fertilizer in water, causing an increase in algae and a decrease in O2. (Nutrient/nitrogen pollution)-mess up the hormones of organisms. (Endocrine disrupters)-lower the pH of rain. (Acid rain)
UNIT 8: ECOLOGY Describe the effects of limiting factors on population
dynamics and potential species extinction Limiting factors: Chemical or physical factor that limits the
existence, growth, abundance, or distribution of an individual organism or a population. Limiting factors determine the carrying capacity.
Examples: Predators: little or no predators will cause an increase; too many
predators will cause a decrease. Nitrogen: plants and animals cannot use nitrogen in gas form; it has
to go through nitrogen fixation by bacteria first. Without enough useable nitrogen plants cannot grow well which would limit the food available to animals. So too little nitrogen would lower the capacity, excess nitrogen would raise the capacity.
Food availability: too little food causes a decrease; excessive food will cause an increase.
Weather: storms, droughts, frosts, etc. can all decrease the carrying capacity by decreasing things like food. Good weather can increase the amount of food available which would increase the capacity.
Disease: generally diseases lower the carrying capacity.
VIDEO REVIEW
Energy Flow Trophic levels
VIDEO REVIEW
Symbiosis
VIDEO REVIEW
Human Impact Threats to Biodiversity
