3.3- Energy Flow in Ecosystems Flashcards
How does energy flow through an ecosystem?
in a one-way stream from primary producers to various consumers
What is a food chain?
a series of steps in which organisms transfer energy by eating and being eaten
Example of a food chain:
Prarie ecosystem: grass > antelope > coyote (two-step chain)
What is phytoplankton?
primary producers found in aquatic food chains (a mixture of floating algae)
What is a food web?
a network of feeding interactions
Why do we use food webs?
many animals eat more than one kind of food; links together all of the food chains in an ecosystem
Each path you can trace through a food web is:
a food chain
Decomposers convert:
dead material to detritus, which is then eaten by detritivores
Decomposers’ process releases nutrients that:
can be used by primary producers
Decomposers recycle nutrients in food webs, with out them:
nutrients would remain locked within dead organisms
What is zooplankton?
diverse group of small swimming animals that feed on marine algae
ex: Krill
Enviromental distubances (in food webs/ecosystems) can:
have dramatic effects; in southern ocean ecosystem, many animals depend directly or indirectly on krill; with sea ice melting fewer algae can grow, reducing krill population and consquently reducing pop. of other animals
What is a trophic level?
each step in a food chain or web
What is the 1st trophic level?
primary producers
What are ecological pyramids?
show the relative amount of energy or matter contained within each trophic level in a given food chain or food web
How to we use ecological pyramids?
to illustrate trophic levels in an ecosystem
What are the 3 types of ecological pyramids?
pyramids or energy, biomass, and numbers
What do pyramids of energy show?
the relative amount of energy avaliable at each trophic level in a food chain/web
Why is only a small portion of the energy that passes through any given trophic level is ultimatley stored in the bodies of organisms of the next level?
because organisms expend much of the energy they acquire on life processes and most of remaining nergy is released in to the environment as heat
How much energy that is avaliable within a trophic level is transferred to the next?
about 10%, but it can vary
ex: primary producers- 100% 1st level consumers- 10% 2nd level consumers- 1%
The more levels that exist between a producer and a consumer:
the smaller the % of the original energy from producers is avaliable to that consumer
What is biomass?
the total amount of living tissue within a given trophic level
How is biomass measured?
in grams of organic matter per unit area
amount of biomass a trophic level can support is determined by:
amount of energy avaliable
What does a pyramid of biomass show:
relative amount of living organic matter avaliable at each trophic level
What does a pyramid of numbers show?
relative number of individual organisms at each trophic level
What are the 2 shapes of pyramids of numbers?
number of individuals decrease at each trophic level, or 1 large primary producer (number of indiviuals increase- so pyramid is turned upside down)
Food chain vary in…
length
two step food chain, four step food chain
Ex: prarie ecosystem: buffalo grass, antelope, coyote
How did wolves introduced in Yellowstone affect the ecosystem?
Energy flow in a food web is:
multidirectional
How are prarie dogs a keystone species?
