Human influences on the Environment

Thèmes abordés

Respiration, Plant cells, food web

Résumé du document

Respiration releases energy from breakdown of glucose
Plants can convert glucose into many other organic molecules, usually starch stored in leaves, roots or other organs. Some converted into sugars (like fructose or sucrose) used to make cellulose in cell walls.
Plant cells can convert glucose into lipids needed to make cells' membrane

Contain only three elements carbon, hydrogen, oxygen (made from glucose)
But for amino acids, need nitrogen => get it from soil as nitrate ions (with other minerals: magnesium to make chlorophyll, phosphate to make DNA and ATP)

Feeding relationships
Food chain show feeding relationships, different stage = trophic levels

Clearer picture is a food web, linking several food chains

Extraits

[...] Becteria oxide organic material, then passes to a sedimentation tak where activated sludge settles out. Some return to aeration tank and purified discharged. Both methods rely on complex ecosystem of aerobic bacteria, fungi, protozoa and other O digest sewage. Fungi and bacteria start the breakdown process, proteins ammonia nitrates. Protozoa and larger invertebrate feed on bacteria and fungi. [...]

[...] But: higher concentration of inorganic ions at end eutrophication. Waste sludge in tank must be treated: anaerobic digestion, produce biogas as waste (mixure of methane, by bacteria the methanogens) and CO2) can be used as fuel. Pit latrine Composting toilet (where no sewage): a hole in ground over a sunken pit pit latrine: user squats over shallow trech ventilated improved pit latrine: covered pit and vent pipe leading from the pit, take away odours. Vent pipe acts like chimney, producing suction effect that draws clean air through latrine Flies and mosquitoes drawn upwards, prevent from leaving the pit by the fly screen. [...]

[...] Humans use these natural recycling processes in treatment of sewage Sewage treatment In developed countries waste carried away in sewers to be treated before enters waterways. If sewage untreated, two major problems: - aerobic bacteria use up dissolved oxygen in water as they break down organic materials, depletion of oxygen kills larger organisms - contains pathogenic bacteria, a health hazard Aim of sewage treatment: remove solid and suspended organic matter and pathogenic MO Two methods: - percolating (biological) filter method Sewage screened to remove large objects and stored in tanks, then pumped through a pipe rotating over the filter bed and trickles through the filter. [...]

[...] Chapter 14 Human influences on the Environment Ecosystems = distinct, self-supporting system of organisms interacting with each other and with their physical environment. Components: - producers green plants (photosynthesise to produce food) - consumers animals (eat plants or animals) - decomposers bacteria and fungi (break down dead materials and recycle nutrients) - physical environment non-biological component (water, soil, air , ) Plants and photosynthesis Use inorganic molecules CO2 + water, chlorophyll and light, to make glucose 6CO2+6H2O C6H12O6 + 6O2 Green pigment, chlorophyll, absorbs light energy: converts light energy into chemical energy. [...]