Topic 4 Flashcards
Species
group of organisms that can interbreed to produce fertile, viable offspring
population
a group of organisms of the same species, living in the same area at the same time
Community
a group of populations living together and interacting with each other in a given area
Habitat
the environment in which a species normally lives
Ecosystem
A community and their abiotic environment all interacting with each other at a given time
Ecology
study of relationship between living org, or living org and their env
Ways of obtaining chemical energy
- Autotrophs: synthesise organic molecules from simple inorganic substances. Energy from sunlight or from the oxidation of inorganic molecules
- Heterotrophs: obtain organic molecules by consuming other organisms
- Mixotrophs: use both methods based on resource availability
Types of heterotrophs
- Saprotrophs: Release digestive enzymes and absorb the products of digestion of dead organic matter/fecal matter/humus. external digestion (fungi, bacteria)
- Detritivores: consume non-living remnants of organisms (detritus, dead organic matter) (earthworms, woodlice)
- Consumers: consume living/recently killed organisms
- Herbivore, Carnivore, Omnivore
- Scavenger: feeds on dead/decaying carcasses ->
doesn’t hunt live prey
Inorganic molecules from env
- Autotrophs obtain their inorganic molecules from the env (CHOPN)
- Heterotrophs may obtain some from the environment but mostly obtain the C and N from the organisms they consume
Explain why ecosystems are sustainable [5]
- Nutrient cycling
- Example: Carbon, Nitrogen
- Autotrophs take in nutrients from the surroundings -> travel along food chain -> broken down by decomposers and returned to env
- Energy for photosynthesis from the sun
- Energy is passed down the food chain through feeding
- Autotrophs make food to support the primary consumers
- photosynthesis produces O2 used in resp
- Resp produces CO2 used in photo.
- populations regulated by negative feedback
Explain the movement of energy and inorganic nutrients in an ecosystem [8]
- Autotrophs obtain inorganic nutrients CHOPN from env.
- They obtain energy from sun/oxidation of inorganic molecules
- Light energy to chemical energy via photosynthesis
- Inorganic carbon into organic molecules
- nutrients are passed down the food chain via feeding by consumers
- C compounds a source of usable energy for life
- Respiration returns CO2 to env
- Resp releases stored chemical energy as ATP
- ATP needed to carry out life functions/growth/synthesis/movement
- Energy is lost/not recycled
- Nutrients cycle in a closed system -> finite amount
- nutrients are returned to env when dead organic matter of consumers/autotrophs and their feces are broken down by saprotrophs
3 main components of ecosystem sustainability
- Nutrient availability -> recycled
- Energy availability -> Sun
- Recycling of wastes -> certain bacteria detoxify wastes
Define trophic level
the position an organism occupies in a feeding sequence
What does a food chain show
Linear feeding relationships between species in a community
energy loss
when talking about energy flow in the system remember
-> organic molecules broken down in respiration to form ATP
-> ATP is used to fuel growth/homeos/other life processes
-> heat released as a by-product (energy loss)
Other forms of loss:
- Uneaten parts of food
- Faeces
Biomass
Total mass of a group of organisms (consisting of carbon compounds in the cells and tissues) (g m-2)
- C compounds contain energy -> biomass used as a measure of the amount of energy added to organisms
- biomass diminishes down a food chain -> loss of heat, urea, waste
- therefore limited trophic levels
- Higher TLs need to eat more food -> lesser biomass from food -> more energy expended hunting/searching food -> if the energy spent hunting > energy from food, TL is unviable
What is a pyramid of energy
- graphical representation of the amount of energy in each trophic level
- measures in kJ m-2 yr-1
Carbon cycle
biogeochemical cycle through which carbon is exchanged between different earth spheres: atmosphere, lithosphere, biosphere, hydrosphere
Ways C is stored
CaCO3, CO2 in atm, organic molecules in organisms, fossils/fossil fuels, rocks, CH4, detritus
How autotrophs obtain CO2
Water: diffuses into the aquatic autotroph directly
Terrestrial: diffuses into auto through stomata -. [] of CO2 outside the plant must be higher than inside
What is the compensation point
CO2 absorbed by photosynthesis = CO2 produced by respiration
Forms in which C exists in water
- as a dissolved gas
- as HCO3- ions as:
CO2 + H2O –> H2CO3
H2CO3 ⇌ H+ + HCO3-
HCO3- ⇌ CO3(2-)
Carbonates react with metal ions on the sea bed, such as Ca2+, to form compounds like CaCO3. CaCO3 used to make coral exoskeletons, shells of molluscs, etc.
Formation of methane
Methanogens -> archaen microorganisms that produce methane as a metabolic by-product in anaerobic conditions. form methane from the waste products of anaerobic respiration
2 reactions
CO2 + 4H2 –> CH4 + 2H2O
CH3COO- + H+ –> CH4 + CO2
Locations this occurs:
- wetlands
- digestive tracts of ruminants
- marine sediments
When it is buried in anoxic conditions underwater/sea beds –> forms natural gas reserves
Oxidation of methane reaction, time
- CH4 + 2O2 –> CO2 + 2H2O
- CH4 persists in atmosphere for 12 yr
