Biology 20 IB - Ecology

Species

A group of organisms that can interbreed and produce fertile offspring (members may be reprodutively isolated in seperate populations) 2+ millions described

Population

a group of individuals of the same species who live in the same area at the same time

Community

a group of populations of different species living and interacting with each other in an area

Habitat

the environment in which a species normally lives or the location of a living organism

Ecology

the study of relationships between living organisms and between organisms and their environment

Autotrophs

obtain inorganic nutrients from the environemnt (self feeders) to build their organic components

inorganic nutrients

supply of phosphorus, carbon, and nitrogen is maintained by nutrient cycling between biotic and abiotic componenets

Mixotrophs

species that are both heterotrophic and autotrophic

Trophic Level

feeding level

Primary Producers

-1st trophic level
-autotrophs
-support other trophic levels aka base of food chain
-most use photosynthesis
-few are chemoautotrophs (make organic compounds from inorganic using energy from chemicals)

Consumers

-heterotrophs
-chemical energy in carbon compounds is passed on by feeding
-in/directly consume energy stored by producers
-primary consumer: herbivore, eats producers
-secondary: carnivore eats 1st consumer
-tertiary and maybe quaternary

how to represent energy transfers

food chain, web or pyramid of energy

-detritivores:

heterotrophs that get organic nutrients from detritus (dead matter) by internal digestion (may initiate decomposition into inorganic substances)

saprotrophs

-putrid feeding, obtain nutrients from dead matter by eexternal digestion (secrete digestion enzymes and absorb nutrients) finishes the breakdown into inorganic nutirnets

closed ecosystem

An ecosystem in which no materials can leave or enter, but through which energy from external sources can flow.

open ecosystem

receives inputs from the surrounding environment

nutrients in ecosystem gets recycled

organic matter -> borken down into inorganic matter by saprotrophs and detritivores, recycles so that it can be reused (organic matter compared to energy that cant be returned to its previous form)

Each level of energy

-rule of 10 (10% of energy reaches next level)
-90% used for biological processes, lost as heat, stored as indigestible matter and excreted (can be recovered by scavengers)
-why food chain legnth is restricted
-restricts biomass of higher trophic levels (90% of energy stored doesnt get passed to the next = less organisms supported)

pyramid of energy

-bar represents trophic level not population
-autotroph on bottom
-width represents energy stored
-energy = KJ/m^2/year

biomass

total dry weight of organisms (g/m^s)

pyramid of biomass

width represents dy matter, most exosystems form pyramid shape that mirrors energy pryamid because of the loss of co2, water, and other waste

mesocosms

-models to help investigate sustainability of ecosystems
-closed ones allow energy in/out but fixed supply of matter
-easier to experiment on that natural ecosystems (control variables, smaller = less % and time, without causing damage)