Ecosystems Flashcards
Define an ecosystem?
All the living organisms that interact with one another in a defined area
Two factors that affect an ecosystem?
Abiotic and Biotic
Examples of biotic factors?
Competition, disease, food availability, territory
Examples of abiotic factors?
Light intensity, temperature, water availability, oxygen availability, soil mineral concentration
What produces the most energy for ecosystems?
The Sun
What is a trophic level?
Each stage in the food chain
The first trophic level is called what?
A producer
What is a producer?
An organism that converts light energy into chemical energy by the process of photosynthesis
What is a consumer?
Organisms that obtain their energy by feeding on other organisms
Why don’t food chains have more than 4 trophic levels?
Not sufficient biomass and stored energy left to support any further organisms
What is biomass?
The mass of living material present in a particular place of an organism
How do you calculate biomass?
Net production of biomass = gross production (initial energy) subtracted by the respiratory loss
What is the measurement for biomass?
gm-2yr-1
(grams per meter squared per year)
In a food chain diagram where are the producers always placed?
At the bottom of the pyramid
How much of biomass is consumed by an organism passed onto the next trophic level?
10 percent !!
Equation for the efficiency of trophic levels?
energy available after transfer/ energy available before transfer x 100
Where does the biomass go once entered into an organism?
The environment, lost in urine/excretion, movement, respiration
The unit for the efficiency of energy transfers between trophic levels?
kJm-2year-1
How much sun energy is captured by organic material?
1-3 percent
Why do organisms capture so little sun radiation?
Most hits the Earth and bounces back by clouds, dust and the atmospher
Ways that humans can manipulate biomass through an ecosystem?
Reducing competition by feeding them, using pesticides or fertilizers, destruction of habitat eg:deforestation, routine antibiotic application or heating
Name and describe what a scavenger is?
An organism that breaks/opens up the carcass. An example is hyenas or vultures
What is a decomposer?
An organism that feeds on and breaks down dead plant or animal matter by external digestion
An example of a decomposer?
Fungi or bacteria
Detritivores are what?
Break down organic material by internal digestion, increases the SA for the decomposers
Examples of detritivores?
Woodlice, maggots, worms
Conditions needed for decomposition?
Optimum temperature for digestive enzymes, high oxygen availability, moist water availability
Examples of habitats with no decomposition?
Mountains, volcanoes, amber, peat bogs
How much of the atmosphere is nitrogen?
78%
Why is nitrogen essential?
Essential element for making amino acids and proteins
Why is the nitrogen cycle needed?
The nitrogen in the atmosphere cannot be taken up by plants. It needs to be combined with other elements such as oxygen and hydrogen
4 processes involved in the nitrogen cycle?
Nitrogen fixation, Ammonification, Nitrification and Denitrification
What is involved in nitrogen fixation?
Bacteria such as Rhizobium and Azotobacter combine Nitrogen with Hydrogen to make Ammonia
Where is Rhizobium found?
In the root nodules of leguminous plants, the bacteria has a mutualistic relationship with the plants
Describe ammonification?
Its the process of decomposers converting nitrogen-containing compounds into ammonium ions
Nitrification?
The ammonium ions from ammonification are converted into NITRITES and then become NITRATES used in plants
What is the name of the bacteria involved in nitrification?
Nitrosomonas
When and why does denitrification occur?
In the absence of oxygen (anaerobic conditions) Denitrifying bacteria uses the nitrates as a source of energy for respiration and nitrogen gas is released
What is succession?
The process in an ecosystem where abiotic factors change, causing the biotic factors to change
Primary succession?
Occurs in a newly found area of land, bare rock, no soil or organic matter
Secondary succession?
In areas of land where soil is present but has no plant or animal species (the bare earth after a forest fire)
Examples of primary succession occuring?
Volcano eruptions, sand blown by the wind, glaciers retreating
