Biology atar (whats on the test)

what is primary succession

colonisation of an area that has never before sustained life

example of primary succession

a new volcanic island

pioneer species

begins with autotrophic prokaryotes for example fungi.

intermidiate of primary succession

grasses and shurbs

climax community

shade tolerant trees

what is seacondary succession

occurs in areas where all previous life has been distroyed

example of seacondary succession

after fire

keystone species

a species that is not necessarily abundant in an area but has a strong control on the structure of the communtiy due to its ecological niche

example of keystone species

nortern quoll because of ecological balances, feeding on diverse diet including insects, mammals, reptiles

what are trophic levels

trophic levels are the different stages in the food chain that repersent the flow of energy from one group of organsims to another

pyramids of biomass

the total amount of matter present in living organisms at each tropic level at a given time in an ecosystem

equation of pyramid of biomass

total number of organisms at each trophic level x average weight of all organisms

pyramid of number

shows the number of organisms at each trophic level in a food chain

pyramid of energy

the amount of energy input into each trophic level iin a given ecosystem over an extended period

how much energy is passed on each trophic level

10% of energy to next trophic level

in what format is pyramid of biomass

KJ/M²/Y

competitive exclusion principal

if 2 species share the same mode of life and use the same resources they cannot co-exist in the long term

ecological niche

the way of life and the role an organism play in an ecosystem for example habitat, predation

what are K selected species

species that produce few offspring, high parental care, stable enviroment and slow growth for example kangaroos

what are R selected species

species that produce many offspring, low parental care, unstable enviroment and fast growth for example rats

density dependent

influence by the population density or level of crowding for example food supply, habitat

density independent

affect all individuals equally regardless of population size for example rainfall, temperature

what is natural selection

a gradual non-random process by which biological traits become either more or less common in a population

3 types of natrual selection

1. stabilising selection

2. directional section

3. disruptive selection

what is stabilising selection

natural selection that favours average individuals

what is directional selection

natural selection that favours an extreme form of a trait

what is disruptive selectino

favors individuals with either extreme form of a trait

what is parasitism

one organisms benefits at expense of the other

what is commensalism

one organisms benefits while the other is niether helped or harmed

what is mutalism

both organisms benefit from the relationship

example of parasitism

musqutios get nutrients from humans blood

example of commensalism

clownfish live among the stinging tenticles of anemons gaining protection and the anemone is unaffected

examples of mutalism

fish clean the teeth of shark and sharks provide fish with protection

what is capture- mark- recapture

used to estimate population size in a closed population especially useful for mobile species

how to calculate capture-mark-recapture

Number marked in first sample (M) x total number of animals recaptured (n)  / number of recaptured animals that are marked (m)