Ecosystems Part 2
Carbon cycle
Respiration
Photosynthesis – plants
Death and decay- animals and plants into fossil fuels
Combustion
Consumption of plants into animals
CO2 enters leaf by diffusion through the stomata
Carbohydrates, lipids and proteins and DNA contain carbon. When eaten by animals, they are
digested and broken down into smaller molecules then synthesized as proteins, amino acids, lipids
and carbohydrates and the rest is stored as biomass.
Lipids, proteins, carbohydrates and DNA contribute to the biomass of an organism. Urea and Co2
excreted which contain urine. Animals egest faeces containing undigested food with carbon in it.
Dead animals, egested and excreted products decompose by saprophytic digestion by bacteria and
fungi. The decomposers release extracellular enzymes that break down organic matter into small
molecules which are then absorbed by diffusion into bacteria and fungi cells. If dead plants and
animals are not decomposed then they become fossil fuels or fossils.
Deforestation, urbanisation and drought are reducing photosynthesis. Combustion, respiration and
decomposition increase CO2 in atmosphere. Combustion increases in winter and photosynthesis
increases in summer.
Micro-organism are important in recycling carbon by saprophytic digestion and allowing carbon to
re-enter cycle.
Water cycle
Water is important to living organism:
Respiration
Cytoplasm
Keep cell turgid
Maintain blood viscosity
Osmoregulation
Thermoregulation
Process:
When sunlight warms up ocean bodies water evaporates from them, forming water vapour
in the air.
It condenses to form clouds.
Trees transpire so water evaporates from the surface of the leaves into the atmosphere.
Rain falls to land and sea and ground as precipitation and through percolation infiltrates the
ground because the ground/rock is porous.
Water will also run off to water bodies such as oceans from percolated water/from high to
low ground.
Potable water
, The increase in human population has led to an increase in global demand for clean water, which is
used in drinking, sanitation and agriculture to produce food. Climate change has made rainfall less
predictable. Rainfall is concentrated in some areas of the world and scarce in others so some areas
suffer drought and have developed techniques to create potable water.
Desalination:
This is obtaining fresh water from sea or salty water. Water intake into the desalination plant is
pumped 3 times slower than the swimming of fish to prevent the death of aquatic organisms.
Filtration is done to remove algae and sand.
Reverse osmosis – salt water meet membrane so fine only water molecules pass through, high
pressure but not osmosis
Evaluation of desalination in producing potable water:
Getting water in dry areas – good
Water can be recycled by diluting and putting it back into the ocean
The plant is run with the energy from reverse osmosis
High abundance of sea water
However cannot supply cities inland
Relatively expensive
Algae is removed from food chains and It will also remove habitats or displace them
Using a solar still:
Sea water is put into trough at base of still
Water evaporates due to energy of sun and salt is left behind
Water condenses under cold surface
Water runs along edge and drops at edges
Collected in water trough
Using nets to get water from mist in desert:
Fog with water vapour condenses when meeting the cold surface of the mesh
The tiny pores
Collected by pipes at base of net
Water treated by chlorination, filtration and antibiotics
Nitrogen cycle
Rhizobium bacteria – nitrogen fixing bacteria in root nodules of legumes e.g. peas, beans, lentils
convert nitrogen gas into nitrates
Denitrifying bacteria – convert nitrates in the soil into nitrogen gas
Nitrifying bacteria- convert ammonium ions into nitrites then nitrates
Nitrogen fixing bacteria – convert nitrogen gas into nitrates in soil
Decomposers – decay dead plants and animals into ammonium ions
Nitrogen converted into nitrate ions by nitrogen fixing bacteria in soil, taken up by root hair cells
by active transport which requires energy.
Carbon cycle
Respiration
Photosynthesis – plants
Death and decay- animals and plants into fossil fuels
Combustion
Consumption of plants into animals
CO2 enters leaf by diffusion through the stomata
Carbohydrates, lipids and proteins and DNA contain carbon. When eaten by animals, they are
digested and broken down into smaller molecules then synthesized as proteins, amino acids, lipids
and carbohydrates and the rest is stored as biomass.
Lipids, proteins, carbohydrates and DNA contribute to the biomass of an organism. Urea and Co2
excreted which contain urine. Animals egest faeces containing undigested food with carbon in it.
Dead animals, egested and excreted products decompose by saprophytic digestion by bacteria and
fungi. The decomposers release extracellular enzymes that break down organic matter into small
molecules which are then absorbed by diffusion into bacteria and fungi cells. If dead plants and
animals are not decomposed then they become fossil fuels or fossils.
Deforestation, urbanisation and drought are reducing photosynthesis. Combustion, respiration and
decomposition increase CO2 in atmosphere. Combustion increases in winter and photosynthesis
increases in summer.
Micro-organism are important in recycling carbon by saprophytic digestion and allowing carbon to
re-enter cycle.
Water cycle
Water is important to living organism:
Respiration
Cytoplasm
Keep cell turgid
Maintain blood viscosity
Osmoregulation
Thermoregulation
Process:
When sunlight warms up ocean bodies water evaporates from them, forming water vapour
in the air.
It condenses to form clouds.
Trees transpire so water evaporates from the surface of the leaves into the atmosphere.
Rain falls to land and sea and ground as precipitation and through percolation infiltrates the
ground because the ground/rock is porous.
Water will also run off to water bodies such as oceans from percolated water/from high to
low ground.
Potable water
, The increase in human population has led to an increase in global demand for clean water, which is
used in drinking, sanitation and agriculture to produce food. Climate change has made rainfall less
predictable. Rainfall is concentrated in some areas of the world and scarce in others so some areas
suffer drought and have developed techniques to create potable water.
Desalination:
This is obtaining fresh water from sea or salty water. Water intake into the desalination plant is
pumped 3 times slower than the swimming of fish to prevent the death of aquatic organisms.
Filtration is done to remove algae and sand.
Reverse osmosis – salt water meet membrane so fine only water molecules pass through, high
pressure but not osmosis
Evaluation of desalination in producing potable water:
Getting water in dry areas – good
Water can be recycled by diluting and putting it back into the ocean
The plant is run with the energy from reverse osmosis
High abundance of sea water
However cannot supply cities inland
Relatively expensive
Algae is removed from food chains and It will also remove habitats or displace them
Using a solar still:
Sea water is put into trough at base of still
Water evaporates due to energy of sun and salt is left behind
Water condenses under cold surface
Water runs along edge and drops at edges
Collected in water trough
Using nets to get water from mist in desert:
Fog with water vapour condenses when meeting the cold surface of the mesh
The tiny pores
Collected by pipes at base of net
Water treated by chlorination, filtration and antibiotics
Nitrogen cycle
Rhizobium bacteria – nitrogen fixing bacteria in root nodules of legumes e.g. peas, beans, lentils
convert nitrogen gas into nitrates
Denitrifying bacteria – convert nitrates in the soil into nitrogen gas
Nitrifying bacteria- convert ammonium ions into nitrites then nitrates
Nitrogen fixing bacteria – convert nitrogen gas into nitrates in soil
Decomposers – decay dead plants and animals into ammonium ions
Nitrogen converted into nitrate ions by nitrogen fixing bacteria in soil, taken up by root hair cells
by active transport which requires energy.
