1.5 Life Processes in the Biosphere

Comprehensive notes on Unit 1 - The Living Environment, Chapter 5 - Life Processes in the Biosphere.

Covers topics such as Adaptation - and the factors affecting it; Ecological Succession; and Natural Population Economies - and the patterns we see.

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  • Created on: 30-12-11 11:54
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1.5. Life Processes in the Biosphere
Adaptation
o Populations are adapted to a range of tolerance; large gene pool = easier to adapt to changes.
1. ABIOTIC FACTORS
Controls distribution of species. Adaptation to extreme conditions eliminates competition, but may limit habitat.
o TEMPERATURE
Low = no enzymes, Hot = denatured. So: temperature fluctuation is dangerous (homeostasis/behaviour-cold blood)
o LIGHT
Energy source. Adaptations include: coloured pigment on forest floor due to green light only.
UV can damage skin cells; esp. thin layers ­ amphibians.
o pH
Exposed living tissue can be damaged. Plants only grow in certain soils & exoskeletons can be dissolved!
o WATER
Frogs must remain moist; also depend on water to lay eggs.
o MINERALS/NUTRIENTS
Plants find nutrients from soils around them....
The Sundew- Lives in anaerobic, waterlogged conditions; but finds the nitrates it lacks from the soil by
trapping and digesting small insects = no competition due to poor quality soil.
o TURBULANCE & PHYSICAL DAMAGE
Adaptations include: flexibility, mucus coating (brown seaweed) / long thin leaves with longitudinal veins (palms)
o >> SPECIES INTERDEPENDANCE AND CONTROL OF ABIOTIC FACTORS...!
When species influence abiotic factors, desirable habitats for adapted species arise, and interdependence evolves.
light may be reduced on the woodland floor due to shade creation >> only green light (pigment)
transpiration above will cause humidity to increase; but wind decreases due to vegetation windbreaks
dense vegetation = increased decay of dead material = nutrients availability increases
2. BIOTIC FACTORS
o FEEDING
Heterotrophs only get compounds from other organisms; so must adapt to efficiently catch/hunt/eat them.
High plant productivity = many species live together w/ specialised feeding mechanisms (e.g. birds' bills) e.g. >>Parrots
are adapted to open seeds + fruit > conservation must preserve tree species which bear certain foods.
o AVOIDING PREDATORS
Plants: bad taste/toxin/thorns Animal: Camouflage/ Habitat (tree-dwelling)
o SYMBIOTIC NUTRITION >> two organisms living alongside each other (and benefitting from it)
e.g. algae living inside coral polyp are provided with shelter and food, and produce carbohydrates for the polyp
o POLLINATION & SEED DISPERSAL
Plants with low pop. densities have adapted to have flowers to attract pollinators because wind would be too
unreliable.
Wind dispersal is specific to small seeds/windy areas ­ adapted to be eaten and dropped/egested later (fruit/nuts)
o DISEASE
Naturally controls pop and eliminates weaker individuals for the better of the species as a whole ­ natural selection.
SQUIRREL POX: Carried by Grey Squirrels, affects Red Squirrels
o In areas of co-existence, attempts have been made of separation, e.g.no use of feeding stations.
o NUTRIENT SUPPLY
Detritus feeders and decomposers recycle dead matter, which provides a food source as the plants use nutrients to
grow.
o INDIRECT BENEFITS
To protect an individual species it may be necessary to protect a complete community

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Grouping Organisms (taxonomy) & Environments
o TAXONOMY ­ study of grouping organism: groups are called taxons; e.g. genus ­ group of closely related species
o SPECIES = A group of very similar organisms which naturally form a reproductively isolated group
Species cannot interbreed due to the inability of matching different chromosomes; very close species may be able to
do this, but this would not occur in the wild due to distribution or differences in behaviour e.g. courtship.…read more

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Diversity & Ecological Stability
o Stable environments = areas with higher diversity & less extreme abiotic factors.
o SIMPSON'S DIVERSITY INDEX is commonly used ­ you have to learn this!!
The higher the value, the higher the biodiversity
o We estimate that there are many species still undiscovered (2 million known out of 5-100 million possible species)
o This could be due to... inaccessible areas not being researched ...similar appearance of different species.…read more

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Carrying capacity: regulates a population because the Density Dependant Factors become stronger if a
population exceeds the CC or weaker when a population feels below the CC ­ resulting in stability.
Predator:Prey Relationships: at times when prey is plentiful, predator numbers will increase after a lag time;
prey numbers will then decrease after a similar lag time, and so forth. Thus, regulating the populations.
Artificial Pop.Control (Culling): necessary when natural control mechanisms (predators) are no longer
available.…read more

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