Ecosystems Flashcards
(28 cards)
Ecosystem
- An area that includes all living and non-living factors and their interactions
Niche
- The role of an organism in its environment, what it eats, its habitat, and its interactions with species
Species
- Group of similar organisms in physiology and genetics that can interbreed to produce fertile offspring
Biotic Factors
- All factors linked to living organisms
- E.g. food, disease, predation, grazing, parasites, humans
Abiotic Factors
- All non-living factors
- E.g. pH, O2 conc, light intensity, water, temp
Producers start food chain, yet only 1-3% of available light is used to make biomass, why?
- 90% of light is reflected
- Only blue/red wavelength used
- Light can transmit through a leaf without hitting a chloroplast
Autotroph
- Organism that converts inorganic molecules into organic molecules
Heterotrophic
- Consumes organic molecules from other organisms to make its own organic molecules
Why is energy lost at each trophic level in a food chain?
- Not all eaten (fur, bones, beaks, feathers, roots)
- Respiration and maintenance of body temperature
- Faeces and urine
What do arrows represent in a food chain?
- The transfer of energy
Describe how you would gather data for a pyramid of energy
- Collect all living material in a given area
- Dry at 105 degrees Celsius
- Record mass
- Burn in CO2 calorimeter
- Calculate the water temperature rise
Which type of pyramid cannot be pyramid shaped due to parasites?
- Pyramid of numbers
How do we measure ecological efficiency from one trophic level to another?
- ENEGRY BIOMASS after the transfer and divide it by the ENEGRY BIOMASS before x 100
- Efficiency = after/ before x 100
Typical units for biomass and energy when studying ecosystems
- g/m-² or g/m-³
- j/m-² or j/m‐³
Why do primary consumers receive a lower % transfer of energy than secondary consumers?
- Primary consumers take in cellulose which is harder to digest than protein and fats
Net Primary Production formula
- NPP= Gross primary production- Respiratory losses
How does carbon get into the atmosphere?
- Combustion (fossil fuels/ wood)
- Respiration
How does carbon get out of atmosphere?
- Photosynthesis
- Dissolves into oceans
Name the forms of nitrogen fixing bacteria and where they are found
- Azotobacter (free in the soil)
- Rhizobium (root nodules of legumes e.g. clovers/ peas)
How do nitrates NO-³ get into soil from dead organic material and waste?
- Organic material converted by saprobiotic bacteria into Nh⁴- ( ammonia ions) by ammonification
- NH⁴- to NO²- (nitrites) by nitrosomonas
- NO²- to NO³- (nitrates) by nitrobacter
How do nitrates NO³- sometimes end up back as N² nitrogen gas in the air?
Anaerobic dentrifying bacteria psuedomonas
What is succession?
- Changes in abiotic factors e.g. soil/humus
- Caused be decomposition of current species
- New species colonise which outcompete earlier species
- This process repeats until a climax community is formed
What are the seral stages in succession?
- Pioneer species = lichen and xerophytes and wind pollinators
- Secondary colonisers = mosses
- Tertiary colonisers = grasses and ferns
- Scrub land = shrubs and bushes
- Climax community = mature woodland
What are different types of succession?
- Primary = from bare rock
- Secondary = soil /humus present after a fire
- Deflected = succession stopped e.g. grazing/ burning (creates a plagioclimax community)
