Ecology Flashcards
Define Species
A group of organisms that can potentially interbreed to produce fertile, viable offspring
Define Population
A group of organisms of the same species that are living in the same area at the same time
Define Community
A group of populations living together and interacting with each other within a given area
Defiine Habitta
The environment in which a species normally lives, or the location of a living organism
Define Ecosystem
A community and its abiotic environment (i.e. habitat)
Define Ecology
The study of the relationship between living organisms, or between living organisms and their environment
Define Autotroph
Organism that produce their own organic molecules using either light energy or energy derived from the oxidation of chemicals
Define Heterotrophs
Organisms which obtain organic molecules from other organisms
Define Detritivores
Organisms which ingest organic molecules found in the non-living remnants of organisms (e.g. detritus, humus)
Define Saprotrophs
Organism which release digestive enzymes and then absorb the external products of digestion (decomposers)
Define Consumers
Organisms which ingest organic molecules from living or recently killed organisms
Define Scavenger
A type of consumer that principally feed on dead and decaying carcasses rather than hunting live prey
List 3 Sapotrophs
Bacteria
Fungi
Mold
List 3 Detritivores
Snail
Earthworm
Crab
Explain how nutrients are recycled
Autotrophs obtain inorganic nutrients from the air, water and soil and convert them into organic compounds
Heterotrophs ingest these organic compounds and use them for growth and respiration, releasing inorganic byproducts
When organisms die, saprotrophs decompose the remains and free inorganic materials into the soil
The return of inorganic nutrients to the soil ensures the continual supply of raw materials for the autotrophs
What are the three components necessary for ecosystem sustainability
Energy availability – light from the sun provides the initial energy source for almost all communities
Nutrient availability – saprotrophic decomposers ensure the constant recycling of inorganic nutrients within an environment
Recycling of wastes – certain bacteria can detoxify harmful waste byproducts (e.g. denitrifying bacteria such as Nitrosomonas)
How does energy enter a food chain and how does in transfer?
Light energy is absorbed by photoautotrophs and is converted into chemical energy via photosynthesis
This light energy is used to make organic compounds (e.g. sugars) from inorganic sources (e.g. CO2)
Heterotrophs ingest these organic compounds in order to derive their chemical energy (ATP)
When organic compounds are broken down via cell respiration, ATP is produced to fuel metabolic processes
Define Trophic level
The position an organism occupies within a feeding sequence
Define Food Chain
A food chain shows the linear feeding relationships between species in a community
How does Energy leave an Ecosystem?
Energy stored in organic molecules (e.g. sugars and lipids) can be released by cell respiration to produce ATP
This ATP is then used to fuel metabolic reactions required for growth and homeostasis
A by-product of these chemical reactions is heat (thermal energy), which is released from the organism
Why is Energy transfer between trophic levels only 10%
Not all energy stored in organic molecules is transferred via heterotrophic feeding – some of the chemical energy is lost by:
Being excreted as part of the organism’s faeces
Remaining unconsumed as the uneaten portions of the food
Define Biomass
The total mass of a group of organisms
List the 4 Spheres on Earth
The four spheres are the atmosphere (air), lithosphere (ground), hydrosphere (water / oceans) and biosphere (living things)
What is Carbon stored in?
Atmospheric gases – mainly carbon dioxide (CO2), but also methane (CH4)
Oceanic carbonates – including bicarbonates dissolved in the water and calcium carbonate in corals and shells
As organic materials – including the carbohydrates, lipids and proteins found in all living things
As non-living remains – such as detritus and fossil fuels
What are the immediate processes
Fuel–>Car–> Atmosphere
Extraction
Pollution
How does the ocean pH decrease?
Carbon dioxide dissolves in water and some of it will remain as a dissolved gas, however the remainder will combine with water to form carbonic acid (CO2 + H2O ⇄ H2CO3)
Carbonic acid will then dissociate to form hydrogen carbonate ions (H2CO3 ⇄ HCO3– + H+)
This conversion also releases hydrogen ions (H+), which is why pH changes when CO2 is dissolved in water (> acidic)
How is limestone developed?
When the hydrogen carbonate ions come into contact with the rocks and sediments on the ocean floor, they acquire metal ions
This commonly results in the formation of calcium carbonate and the subsequent development of limestone
How do organisms utilize carbonate ions?
Living animals may also combine the hydrogen carbonate ions with calcium to form calcium carbonate
This calcium carbonate forms the hardened exoskeleton of coral, as well as forming the main component of mollusca shells
When the organism dies and settles to the sea floor, these hard components may become fossilized in the limestone
Define Methanogens
Archaean microorganisms that produce methane (CH4) as a metabolic by-product in anaerobic conditions
How do Methanogens produce methane from the by-products of anaerobic digestion, principally acetic acid and carbon dioxide:
Acetic acid → Methane and Carbon Dioxide (CH3COO– + H+ → CH4 + CO2)
Carbon Dioxide and Hydrogen → Methane and Water (CO2 + 4 H2 → CH4 + 2 H2O)
How does methane accumulate under the ground?
When organic matter is buried in anoxic conditions (e.g. sea beds), deposits of methane (natural gas) may form underground
Why is methane in low abundance in the atmosphere?
Methane will be naturally oxidised to form carbon dioxide and water (CH4 + 2 O2 → CO2 + 2 H2O)
How is peat formed?
Anaerobic respiration by organisms in water logged regions produces organic acids (e.g. acetate), resulting in acidic conditions
Saprotrophic bacteria and fungi cannot function effectively in anaerobic / acidic conditions, preventing decomposition
Since the organic matter is not fully decomposed in waterlogged soils, carbon-rich molecules remain in the soil and form peat
How is coal formed?
When deposits of peat are compressed under sediments, the heat and pressure force out impurities and remove moisture
The remaining material has a high carbon concentration and undergoes a chemical transformation to produce coal
How is Oil/Natural gas formed?
Oil (i.e. petroleum) and natural gas form as the result of the decay of marine organisms on the ocean floor
Sediments (e.g. clay and mud) are deposited on top of the organic matter, creating anoxic conditions that prevent decomposition
As a result of the burial and compaction, the organic material becomes heated and hydrocarbons are formed
The hydrocarbons form oil and gas, which are forced out of the source rock and accumulate in porous rocks (e.g. sandstone)
Why are fossil fuels non-renawable?
The formation of fossil fuels (coal, oil and gas) takes place over millions of years, making them a non-renewable energy source
Define Carbon flux
Carbon fluxes describe the rate of exchange of carbon between the various carbon sinks / reservoir
Which Natural Events increase CO2?
Forest fires can release high levels of carbon dioxide when plants burn (loss of trees also reduces photosynthetic carbon uptake)
Volcanic eruptions can release carbon compounds from the Earth’s crust into the atmosphere
How is human Activity increasing CO2 concentrations?
Clearing of trees for agricultural purposes (deforestation) will reduce the removal of atmospheric CO2 via photosynthesis
Increased numbers of ruminant livestock (e.g. cows) will produce higher levels of methane
The burning of fossil fuels will release carbon dioxide into the atmosphere
Which gases cause the green house effect?
Most abundant: Water and CO2
Less abundant: Methane and NOx
Which factors decided on what impact a substance has on the greenhouse effect?
Gases that have a greater capacity to absorb long-wave radiation will have a greater warming impact (per molecule)
The greater the concentration of a gas, the greater its warming impact will be within the atmosphere
The concentration of a gas will be determined by both its rate of release and persistence within the atmosphere
Why is the green house effect nessecary?
It ensures the Earth maintains the moderate temperatures needed by organisms to maintain life processes (homeostasis)
Without a greenhouse effect, Earth’s temperatures would drop significantly at night in the absence of direct sunlight
How does warming of the earth occur via the green house effect?
Incoming radiation from the sun is shorter wave radiation (ultraviolet radiation and the visible spectrum)
The surface of the Earth absorbs short wave radiation and re-emits it at a longer wavelength (i.e. infra-red / heat)
Greenhouse gases absorb and re-radiate this longer wave radiation and hence retain the heat within the atmosphere
What may be the effect of increased global temperature?
More frequent extreme weather conditions (e.g. heat waves, cyclones, more powerful tropical storms, etc.)
Some areas to become more drought affected, while other areas become more prone to periods of heavy rainfall
Changes to circulating ocean currents – which may cause longer El Nino (warming) and La Nina (cooling) events
When did carbon dioxide levels begin to increase?
The industrial revolution introduced new manufacturing processes which significantly increased mankind’s use of fossil fuels
The burning of fossil fuels releases carbon dioxide as a by-product, leading to a steady increase in its atmospheric concentration
How does ocean acidification effect corals? 8 marks
Carbon dioxide will combine with water to form carbonic acid, which dissociates into hydrogen ions and hydrogen carbonate
H+ ions will lower the ocean pH (acidification) and will also combine with free carbonate ions to form more hydrogen carbonate
With less free carbonate ions in the water, marine organisms are less able to produce calcium carbonate (via calcification)
Calcium carbonate is used to form the hard exoskeleton of coral and is also present in the shells of certain molluscs
Hence increasing concentrations of dissolved carbon dioxide threatens the viability of coral reefs and certain molluscs
