1.11 food chains & food webs

food chains/food webs

shows how energy/matter flows in an ecosystem. when one organism preys on another, the matter (c/h2o/n/p) and glucose (muscle,tissue,etc) are passed onto the predator.

how many interconnected food chains do food webs have

at least 2

trophic cascade

removal/addition of a top predator has a ripple effect through lower troph levels

ex. decline in wolf pop.=increase in deer pop which leads to overgrazing/decline in trees

keystone species

an organism, if removed, would cause its ecosystem and food web to be dramatically different or eliminated, keystone species have low functional redundancy

detritivore

breaks/eats dead things (termites)

decomposers

breaks down dead things into simplest parts back into NUTRIENT LEVELS

feedback loops

how systems respond to change

positive feedback loop

feedback loop = causes a system to change further in the SAME DIRECTION

ex. as members of a species reproduce, they create more offspring that will be able to reproduce in turn, creating a cycle that increases the pop. sizen

negative/connective feedback loop

that causes a system to change in the OPPOSITE DIRECTION from which it is moving. it relates to homeostasis, it goes down then comes back up to homeostasis

ex. a drop in water level reduces the lake surface area and evaporation decreases. the decrease in evaporation causes the lake level to rise again back to normal