Life processes in the biosphere

Life processes in the biosphere

1. Abiotic factors

   • Temperature
     • Low temp freeze cells and high temps denature proteins.
     • Fluctuating temps causes problems for enzymes/proteins functioning in optimum ranges, internal body temp must be kept constant (lizards sheltering, birds/mammals generate heat through respiration, increases food requirements but allows them to live in varied environments
   • Light
     • Plants with pigments to absorb light (chlorophyll.) Woodland plants have red/blue pigments to make use of green light passing through the canopy, can't survive bright sunlight.
     • UV damages cells, dangerous to animals with thin skin.
   • pH
     • Many plants only survive if soil is within a particular pH range. Root cell enzymes may not function/absorb nutrients.
     • Acidic conditions dissolves exoskeletons.
   • Water
     • Needed for breeding or because organisms can't reduce water loss. Frogs skin must be moist or living skin cells die and absorption of oxygen is reduced, water needed to lay eggs.
   • Mineral nutrients
     • Sundew: anaerobic, waterlogged soils, shortage of nitrates. Traps and dissolves insects for nitrogen compounds from their proteins. If soil dries out it will be aerobic, nitrogen availability increases and vigorous plants/grasses out-compete the sundew.
   • Turbulence and physical damage
     • Flexibility, mucous coating, long thin leaves with lengthways veins.
   • Species interdependence and control of abiotic factors
     • Woodland: light levels on woodland floor reduced due to shading, light absorption in canopy means floor get little blue/red but more green. Humidity higher due to transpiration by canopy. Wind velocities reduced. Increased nutrient availability due to decomposition.

2. Biotic factors

   • Feeding
     • Parrots: strong, hooked bills to pick and open fruit and seeds. Hummingbirds: long bills and tongues to feed on nectar. Habitat protection includes suitable plants for fruit and nectar throughout the year.
     • Woodpeckers peck into rotten wood for insect larvae. Need enough old rotting trees.
     • Caterpillars of large blue butterfly feed on wild thyme, spend winter in red ants nests feeding on their larvae. Grazed grassland must be maintained so food species thrive.
   • Avoiding predators
     • Defence mechanisms such as bad taste, toxins, thorns or camouflage. Tree-living animals avoid ground.
   • Symbiotic nutrition
     • Algae in coral polyps are provided with a safe habitat and nutrients providing carbohydrates to the polyps in return.
     • No animals can produce cellulase, can't digest cellulose. Some herbivores have cellulose-digesting bacteria in intestine.
     • Lady's slipper orchids have small seeds, not big enough to produce young, independant plants. Germinated seeds join with mycorrhizal fungi in soil, receiving sugars, water and mineral nutrients, when grown they return sugars to the fungi.
   • Pollination
     • Wind pollination is haphazard, used by plants in dense groups (grasses.) Plants with low population density need a pollen delivery system, evolved flowers, scent, colour, shape or opening time to attract animals to transfer pollen.
   • Seed dispersal
     • Larger seeds or seeds in sheltered areas can't be carried by wind. Seeds intended to attract animals, some may be carried away and eaten or dropped, some in edible fruit and pass through gut undigested.
   • Disease
     • Naturally control populations, especially when high. Weaker individuals don't survive. If already threatened disease may cause it to decline.
     • Squirrel pox: grey squirrels carry disease but are immune, red squirrels aren't immune. Reds and greys must be separate.
   • Nutrient supply
     • Nutrients from dead organic matter and released during break up by detritivores and subsequent breakdown by decomposeres. Plants utilise nutrients, ensures future food supplies for detritivores and decomposers.
   • Indirect benefits
     • Hole-nesting birds rely on woodpeckers to excavate original holes.
     • Forest elephants make large waterhole clearings (bais) also used by other animals.
     • Mangrove branches absorb energy of storm waves protecting plants inland.

3. Grouping organisms

   • Taxonomy
     • Study of how organisms can be grouped according to how closely related they are, each group being a taxon. Subjective.
     • Kingdom, phylum, class, order, family, genus, species.
   • Species
     • Group of organisms that resemble each other closely, form a reproductively isolated group that naturally breed to produce fertile offspring.
   • Population
     • All individuals of a species living in a particular areas.
   • Community
     • Populations of all species in a particular area.

4. Grouping environments

   • Ecosystem
     • Community of organisms living in an area, inter-relationships and interactions with their abiotic environment.
   • Habitat
     • Place where an organism, species or population live.
   • Niche
     • The role a species plays in its habitat, includes the way it uses environmental resources and the way it changes its environment.
     • No two species can occupy the same niche, one would be better adapted and out-compete the other.
   • Biome
     • Large, geographical region with particular climatic features in which a characteristic unique community of species live.
     • Distribution controlled by temp, light levels, water availability and seasonal fluctuations.
   • Biosphere
     • Part of the planet that is inhabited by living organisms: land surface, soil, water and atmosphere.