Ecology: Chapter 3 Flashcards
Biosphere
part of the earth where life exists; extends from about 8 km above the earth’s surface and 11 km below the surface of the ocean
Ecology
the study of interactions of organisms with one another and their physical environment
Biological Species
All organisms of one kind that are so similar to one another that they can produce fertile and viable offspring
Population
Groups of individuals that belong to the same species and live in the same area
Community
Assemblages of different populations that live together in a defined area
Energy Flow
- every action of every organism requires energy
- the amount of energy available is the single most important factor in determining how many and what kinds of organisms live in an ecosystem
- the main energy source for life on earth is the sun
- less than 1% of this energy is actually used by living things
(Primary) Autotrophs or Producers
Organisms that make their own food (complex organic molecules) using inorganic raw materials in their environment; these organic molecules are used to synthesize living tissue
- example: some prokaryotes, specifically the Cyanobacteria; all algae; all plants
Autotrophs or Producers
- Most of these organisms use sunlight as their energy source and make their own food by a process called photosynthesis
- others rely on the energy stored in inorganic chemical compounds (hydrogen sulfide) to produce their own food, this is a process known as chemosynthesis
- example: certain bacteria living in hot springs or undersea vents (hostile environments)
Consumers or Heterotrophs
Organisms that cannot make their own food and therefore must rely on other organisms for their energy and food supply
-example: many Protists and bacteria (both unicellular, simple multicellular); all animals and all fungi
Herbivores
Obtain their energy by eating only plants/producers
-example: cow, grasshoppers, lady bug, deer, gorilla
Carnivores
Obtain their energy by eating animals/consumers
-examples: praying mantis, dragonflies, frog, centipede, shark
Omnivores
Obtain their energy by eating both producers and consumers
-example: Bears, skunk, possums, raccoon, humans
Detritivores
Feed on animal and plant remains and other dead matter (collectively referred to as detritus); also called saprobes or reducers; all are consumers
-example: mites, earthworms, snails, and crabs
Decomposers
A specific type of detritivores; microscopic organisms that break down and absorb organic matter (found in wastes and dead organisms)
-example: bacteria and fungi of decay
Scavengers
Organisms that feed on larger remains of dead organisms
-example: vultures and hyenas
Feeding Relationships
- energy flows through ecosystems in one direction from the sun or inorganic compounds (the two main forms of energy that power living systems)- first to producers and then to various consumers
Food chains
A series of steps in which organisms transfer energy by eating being eaten
-the first link (the base) is always a producer; the arrow always points to the eater
Plankton
Tiny free floating or weakly swimming microorganisms that occur in aquatic environments
Phytoplankton
Plankton that photosynthesizes; algae
Zooplankton
Heterotrophic plankton; include larvae (immature forms) of many organisms
Primary or first order consumers
Those that feed upon producers; all herbivores; the second link in any food chain
Secondary or second order consumers
Those that feed upon first order consumers; carnivores, though some may be omnivorous
Notes regarding food chains
- the first link is always some kind of producer
- first trophic level: producer
- second trophic level and above: consumer
- each consumer depends on the trophic level below it for food and energy
Food Webs
network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem. each food web links all food chains of an ecosystem together
Pyramid of Energy
- as we move from one trophic level to the next, 90% of the energy is lost
- at each trophic level, the energy stored in the organisms is about 10% that of the level below it
What happens to the energy that is passed on?
- It’s used to build tissue and as an energy source
- The more levels that exist between a producer and a top level consumer, the less energy that remains from the original amount. As a result, organisms at higher trophic levels usually tend to be lower in number than those at the lower trophic levels
Pyramid of Biomass
represents the amount of potential food available for each trophic level in an ecosystem
Biomass
- the total amount of living tissue within any given trophic level or ecosystem
- usually expressed as organic matter / unit area
What agent powers the water cycle?
the sun
Transpiration
the evaporation of water through a plants leaves
Evaporation
liquid to gas; have to heat it up
Condensation
gas to liquid; gets colder
Precipitation
condensation around dirt particles –> falls to the earth
Carbon Cycle
- less than 1% of all the carbon on earth actually cycles in the biosphere
- less than 1% of the atmosphere is CO2 gas
- carbon is the key ingredient in all organic compounds
- green houe effect: retention of the sun’s heat; resulting in global warming
Nitrogen Cycle
- the form of nitrogen plants use: ammonia/ammonium or nitrates
- once the nitrogen is in the organism’s cells, it must assimilate it or ultilize it
- nucleotides, ATP, amino acids, proteins
- 79% of our atmosphere is nitrogen
Nitrogen Fixation
N2 –> NH3/NH4+
Ammonification
Nitrogen compounds in dead organisms –> NH3/NH4+
Nitrification
NH3/NH4+ –> NO2- –> NO3-
Dentrification
NO3- –> N2
Phosphorus Cycle
- does not enter the atmosphere
- mainly found in rock/soul and ocean sediments as inorganic phosphate
- plants take it in from the soil / algae take in in from the water
How to consumers get their phosphorus?
By eating
Primary productivity
the rate at which organic matter is created by producers
Limiting Nutrient
-single nutrient that is either scarce or cycles very slowly, limiting the growth of organisms in an ecosystem
Key Limiting Nutrients
a) in the soil: Nitrogen, Phosphorus, and Potassium (the three key minerals listed on fertilizer packages)
b) in oceans: nitrogen, silica, or iron
c) in fresh-water environments: phosphorus
Eutrophication
an ecosystem’s response to the addition of artificial or natural substances such as nitrates or phosphates, to an aquatic ecosystem
Oligotrophic
having few nutrients
Algal Bloom
an unnatural population growth of algae or cyanobacteria
