Life Processes in the Biosphere Flashcards
What are some biotic and abiotic factors organisms can adapt to?
- Low temperature A
- High temperature A
- Low light levels A
- Water turbulence A
- Food B
- Reproduction B
- Symbiosis B
What is meant by ‘Range of Tolerance’?
The range of abiotic factors an organism can survive within.
What is symbiosis?
A relationship where both species benefit e.g. crocodile gets teeth cleaned by a bird, bird gets food.
What is Primary Succession?
Where a community changes over time in an area containing no vegetation or soil (bare rock).
What is Secondary Success?
Where a community changes on a previously colonised but disturbed area.
What is a climax community?
A stable community where no further succession occurs.
How does the process of succession occur for a lithosere?
1) Pioneer species colonise.
2) Change abiotic conditions over time, increase dead organic matter.
3) New colonisers appear and out-compete pioneer species (die out).
4) Abiotic factors become stable, adaptations based more on biotic factors.
5) new species continuously colonise, thrive and die until climax community is reached.
- Changes in plant species diversity, increases food type abailable, tall vegetation decreases light levels etc.
What is a hydrosere?
Similar to lithosere but succession occurs in water first before becoming dry land.
What is psammosphere?
The succession/colonisation of an area of sand.
What is a plagioclimax?
Where human activity has prevented the ecosystem developing further (deflected succession).
What is coppicing?
Young tree stems are cut near ground level as many trees will regrow from the stump.
What is pollarding?
Upper branches are removed to form dense foliage above - often used to maintain trees at a particular height.
Stages of population dynamics
1) Lag phase - pop. becomes established.
2) Logarithmic phase - rapid population growth, little environmental resistance.
3) Slow growth - intraspecific competition/disease/food.
4) Stable, fluctuating phase - density-dependent factors control pop. size.
5) Maximum number the land can sustain - carrying capacity.
What is r and K selected species?
r-selected = High growth rates, offspring have low survival rates, short lifespan.
K-selected = live close to carrying capacity, few offspring, high chance of surviving to adulthood, long lifespans.
When might artificial population control be necessary?
- Introduction of an invasive species.
- Loss of indigenous predator = prey are unregulated.
- Breeding rate of endangered is low so captive breeding needed. NOT CULLING - SUPPLEMENTING POPULATION.
