Week 7: Energy transfers and Nutrient cycles Flashcards
Nutrients that are required for the organism to survive are also known as
Matter (matter takes up space yeet)
Why is energy important?
So organisms can move, synthesise important molecules, maintain a stable internal environment, fight disease and reproduce.
What moves matter?
energy
What is the primary source of energy for most ecosystems?
The sun
In some extreme environments energy can be obtained from
chemical reactions that occur within the ecosystem (e.g. from volcanic eruptions)
food chain
diagram showing organisms feeding on each other
Ecological efficiency
measure of the percentage of energy that is transferred from one trophic level to the next.
Why loss of energy and the transfer being only 10-20% max?
energy used to build and repair body cells, for movement and processes such as generating heat to keep warm and heat being released into environment from organism
How much energy available to plants is stored as organic matter through photosynthesis?
1-3%
Ecological pyramids can be used to show
energy losses along a food chain at each trophic level
Energy is measured in
joules
Why are cycles like phosphorus, carbon, nitrogen and water called biogeochemical cycles?
They utilise biological, geological and chemical processes
The water cycle describes the
continuous movement of water between different reservoirs and storage locations.
Evaporation
heat makes liquid water turn into gas
Transpiration
When water evaporates through leaves of plants (also known as evapotranspiration)
Condensation
When water vapour cools down to form droplets again
Precipitation
When water droplets are large enough to fall in the form of rain snow fleet hail
Infiltration
When water infiltrates the ground and soils to collect underground in aquifers
Run off
when ground is unable to absorb water, runs off down hills to form bodies of water
Root uptakes
When plants absorb water from the soil to their roots
key ingredient of all living tissue
carbon
Biological processes like decomposition photosynthesis and respiration take up and release
carbon
Geochemical processes
release carbon into the atmosphere and oceans through processes like erosion and volcanic eruption
4 main processes that move carbon through cycle are
biological- photosynthesis respiration + decomposition
geochemical - erosion and volcanic activity
mixed biogeochemical-burial and decomposition
Use of nitrogen
to make amino acids, proteins, chlorophyll, nucleic acids (DNA + RNA) and ATP in cells
The only way plants and animals can obtain nitrogen is when its in a
fixed soluble form
molecular nitrogen fixed by
atmospheric events and bacteria that are found in soils.
Nitrogen Fixation
Nitrogen fixing bacteria are found in soils near roots.
They have enzymes that convert molecular nitrogen into ammonia (NH3) in soils.
Nitrification
Nitrifying bacteria convert toxic ammonia (NH3) into nitrates (NO3-) which is now ‘fixed’ nitrogen that is available to plants and animals.
Denitrification
Denitrifying bacteria convert nitrates back into molecular nitrogen
What plants have nitrogen fixing bacteria inside nodules on their roots?
legumes (peas, beans, lentils, etc)
Bacteria and fungi can decompose dead and decaying material back into
ammonium compounds which are also available to plants.
Production of phosphorus for
nucleic acids (DNA and RNA), ATP and phospholipids (which are used to form cellular membranes).
Phosphorus is released when the substances containing them are eroded by abiotic factors to form Phosphates
Phosphorus found in
Rocks, seawater and soils.
Phosphorus released when
substances containing them are eroded by abiotic factors to form Phosphates
Some plants have a mutualistic relationship with
mycorrhiza fungi - that make phosphorus available to plants.
Plants absorb the phosphates and incorporate them into their
tissues
How do animals obtain phosphorus?
by consuming plants and other animals
Phosphorus returns to the soil when
organisms die
How has human activity changed the water cycle?
Removing large quantities of water from rivers for irrigation
(e.g. River Murray)
Releasing pollutants which enter waterways, directly or indirectly
Deforestation where trees normally release water vapour into the atmosphere – decreases water available for precipitation
Increasing atmospheric temperatures increases rate of evaporation.
How has human activity changed the Phosphorus Cycle?
Run-off in fertilisers can cause overgrowth of some species and loss of biodiversity from the ecosystem.
Sewage, including household waste water introduces high levels of phosphorous.
Use of fertilisers depletes stores of phosphate in the soils.
How has human activity changed the carbon cycle?
The burning of fossil fuels + deforestation has increased atomospheric CO2
