6.3.1 Ecosystems COMPLETE Flashcards
Population
All the organisms belonging to one species that live together in the same area, at the same time, and can interbreed.
Community
All the populations of different species that live in the same place at the same time.
Habitat
The place an organism lives
Niche
The role of an organism in the ecosystem including how it feeds, reproduces, finds shelter and how it interacts with its biotic and abiotic environment.
Producer
An organism that transfers energy from light or an inorganic compound to an organic compound.
Consumer
An organism that obtains energy from organic compounds i.e. carbs. Feed on other organisms.
Decomposer
Organisms that feed saprophytically on dead organic matter, releasing mineral ions and other material into the soil and air.
Trophic Level
The stage at which an organism feeds in the food chain
Ecosystem
A relatively self contained unit of living organisms interacting with each other and their abiotic environment
Biotic Factors
LIVING
i.e. grazing, predation, mutualism, pollination, parasitism
Abiotic Factors
NON LIVING
i.e. Temp, water availability, light intensity, wind speed, pH
Ecological efficiency
efficiency of biomass as its transferred through trophic levels
GPP
Gross primary productivity- amount of light converted into chemical energy for photosynthesis
NPP
Net primary productivity- Remaining biomass after respiration to go to the next trophic level
Energy loss in primary productivity
- light not hitting plant
- lands on non photosynthetic part
- other limiting factors i.e.
- lost as heat during evaporation
Energy loss between producer and consumer
- Not all parts of plant are eaten
- can’t digest entire plant (Cellulose)
- lost as heat in digestion
Energy loss between two consumers
- some animals aren’t eaten
- some parts of animal aren’t eaten (bone)
- heat loss during respiration
Pyramid of Numbers
Created by counting numbers of a species, no mention of biomass and effected by seasonal variation
Pyramid of Biomass
Weigh dried out specimen, inconvenient as need to kill specimen
Pyramid of Energy
Once dried you need to burn the specimen, this is time consuming and disrupts the ecosystem
Methods to increase agriculture production
- High crop density, plant in small areas
- Increasing temp and CO2 for photosynthesis
- Crop rotation/ fertiliser so plants have all minerals they need
- good irrigation so stomata remain open
Increasing Secondary Productivity
- Use herbivores
- Restrict their movement
- Antibiotics and steroids
- Kill just before adulthood
- high energy food
Feeding Saprophytically
Secrete enzymes which the digest and hydrolyse large organic molecules into smaller inorganic ones, these are absorbed into the bacteria or fungus’ body.
Free living Nitrogen Fixing Bacteria
e.g. Azotobacter, live in soil taking N gas from air spaces and manufacture amino acids for growth. Once dead they decompose and nitrates are released.
Nitrogen fixing bacteria in Root Nodules
e.g. Rhizobium, live in leguminous plants such as peas, clovers and beans. Have a mutualistic relationship with plant exchanging fixed nitrates for glucose.
Leghaemoglobin in nodes keeps it anaerobic allowing nitrogen reductase to produce nitrates.
Ammonification
Ammonia produced from dead organisms, faeces and urine. Then become ammonium ions by saprophytic fungi and bacteria. Decomposition of amino acids.
Nitrification
1) Ammonium ions oxidised into nitrites by nitrosomonas bacteria.
2) Nitrites oxidised into nitrates by nitrobacter bacteria
Happens in aerated soils, the bacteria are Chemoautotrophic as gain energy from reaction.
Denitrification
Convert nitrates back to nitrogen gas, present tin waterlogged anaerobic soil. Use nitrates as a source of oxygen
Fluctuations in CO2
- Changes during day and seasonally based on rates of photosynthesis
- combustion of fossil fuels has increased levels
Problems with increased CO2
increase in greenhouse effect, leading to global warming,
CO2 dissolving in rain, carbonic acid damages rocks,
as temp rises less CO2 dissolving in oceans
Measuring Distribution
Use transect across a gradient, i.e. distance from path for trampling
Measuring Abundance
Use the SACFOR scale for %Frequency
Capture-Mark-Release-Recapture
Animals may become trap happy or trap shy effecting frequency of catching animals. i.e. marking snails
Measuring Abiotic Factors
Temp= Thermometer Humidity= Hydrometer Light= Luxmeter
Succesion
A directional change in an ecosystem overtime,
Primary=from bare ground to climax
Secondary= from altered state to climax
Deflected= factors preventing climax being reached
Pioneer Community
Organisms that change abiotic features to enable others to settle in the area
Climatic Climax
The final stage when an equilibrium is reached
Lag Phase
a small number of individuals acclimatising to habitat, reproduction is low so slow increase in population
Log Phase
Resources are plentiful so increased numbers of breeding individuals. Birth rate greatly exceeds death rate so population increasing rapidly.
Stationary Phase
Population reached carrying capacity, no longer enough resources, death and birth rates are equal. Numbers fluctuate due to environmental conditions
Density dependant limiting factors
A bigger population means greater % likely to die, i.e. disease or starvation.
Density independant limiting factors
Population size has no effect on % death, i.e. natural disasters or climatic features like it being freezing cold
Competition
Either good competitors and win idea niche, or good at tolerating realised niche. (Interspecific)
