B4.1: Ecosystems Flashcards
How is an ecosystem organised?
- Organism
- Population
- Community
- Ecosystem
What is biomass?
Biomass is the total quantity or weight of organisms in a given area/volume
What are pyramids of biomass?
Used to show how the biomass changes
What is biomass transfer?
Biomass is lost between each trophic level
Importance of nitrogen
- used to make proteins
- have to get nitrogen in the form of nitrates from soil
- use nitrates to produce important proteins
Nitrifying bacteria
Converts ammonia ions into nitrates in the soil
What are biotic factors?
Biotic factors are due to the living organisms in a habitat
Examples of biotic factors
- disease
- predation
- competition
- mates
Why might gardeners add worms to their compost bins?
Worms are detritivores which means they eat large parts of dead material which increases the surface area for decomposers
Food webs
Most animals eat more than one thing so a food web shows the different foods organisms eat
What are abiotic factors?
Abiotic factors are non-living or physical factors in a habitat
Examples of abiotic factors
- temperature
- moisture
- light intensity
- pH
What is a pyramid of numbers?
Shows how many animals or organisms we are talking about
What do the arrows in food chains show?
The arrows indicate where the energy is going
What do food chains show?
They allow us to see feeding relationships and flow of energy through an ecosystem
Detritivores
Eat large parts of dead material and they break down larger waste materials and excrete waste with a larger surface area
- woodlice, maggots, worms and flies
Factors affecting the rate of decomposition
- Temperature: speed it up at the optimum temperature, exceeds -> denature as it is controlled by enzymes
- Water availability: Required but too much could drown, not enough dry up
- Aerobic conditions: more, faster (respiration)
Producers
Organisms that make their own food by photosynthesis
- all plants
Decomposing bacteria
Converts decomposed waste into ammonia -> ions
Denitrifying bacteria
Converts nitrates in the soil to nitrogen in the air
Key processes in the water cycle
- evaporation
- condensation
- transpiration
- precipitation
- surface run-off
- infiltration
- percolation
Key terms in the nitrogen cycle
- nitrogen-fixing bacteria
- lightning
- nitrates in the soil
- decomposers
- decomposing bacteria
- nitrifying bacteria
- denitrifying bacteria
- ammonia (ions)
Consumers
They can’t make their own food so they have to eat other organisms to gain energy
- all animals
Decomposers
They chemically break down dead material - produce nitrogen based products
What are decomposers?
Special group of consumers - they gain their energy by feeding on dead or decaying material
Nitrogen-fixing bacteria
Convert nitrogen in the air to nitrates in the soil (in root nodules)
Key processes in the carbon cycle
- respiration (both plants and animals)
- photosynthesis
- combustion
- eating
Equation for rate of decay:
Rate of decay (g/day) = change in mass (g) / time (no. of days)
