Interdependence Flashcards
What do plants need to compete for in order to survive and reproduce?
- light
- space
- water
- minerals (nutrients) from the soil
In what ways do environmental changes affect communities?
- population size increases: e.g. if number of prey increase, there is more food available for predators, so more predators survive and reproduce, increasing their numbers
- population size decreases: e.g. US number of bees are falling rapidly - due to pesticides, less nectar-rich food available, more disease
- population distribution changes: - a change in where an organism lives
- e.g. European bee-eater is a Mediterranean species but now present in Germany
What are indicator species?
- organisms that are very sensitive to changes in their environment, so can be studied to see the effect of human activities
What are the living and non-living factors that causes environmental changes?
Living factor:
- a change in the number or types of competitors
Non-living factors:
- a change in average temperature
- a change in availability of nutrients
- a change in the amount of light
- a change in average rainfall
- a change in availability of oxygen and carbon dioxide
- a change in the availability of nesting sites, shelter and habitats
How do you work out population size?
- work out the number of organism per m^2
- multiply the mean by the total area of the habitat
- e.g. total area is 800m^2 and there are 22 daisies per m^2 22 x 800 = 17600
How can you make sure results are more valid?
- they must be repeatable, reproducible and answer the original question
- more likely to be valid if you use random samples, so that it’s not all one spot
Give examples of non-living indicators of environmental change
- satellites: measure the temperature of the sea surface. they are accurate, modern and give global coverage
- automatic weather stations: tell us the atmospheric temperature. they contain sensitive and accurate thermometers and can measure to very small fractions of a degree
- rain gauges: measure rainfall, to see how much average rainfall changes year on year
- dissolved oxygen meters: measure concentration of dissolved oxygen in water. sees how water pollution is changing
Give examples of living indicators of environmental change
- lichens: air pollution indicators as they are sensitive to the concentration of sulphur dioxide in the atmosphere. Air is clean when there are lots of lichen
- invertebrate animals: such as mayfly larvae, are present when water is clean. rat-tailed maggots, sludge worms have adapted to live in polluted conditions so high level of pollution
What do animals need to compete for in order to survive and reproduce?
- space (territory)
- food
- water
- mates
How can you make sure results are more reproducible?
- use a large sample size (e.g. as many quadrats and transects as possible in your sample area)
- bigger samples are more representative of the whole population, so more reproducible
How do you use quadrats to study the distribution of small organisms using random sampling?
- place a 1m^2 quadrat on the ground at a random point within the first sample area (using a random number generator)
- count all the organism within the quadrat
- repeat 1 and 2 as many times as possible
- work out the mean number of organism per quadrat within the first sample area, median, mode also
- repeat in the second sample area
- compare the two means
What are the pros and cons of using non-living indicators?
Pros:
- directly measuring pollutants of environmental change gives reliable, numerical data that’s easy to compare between different sites
- the exact pollutants can be identified and their concentrations measured
Cons:
- requires expensive equipment
- trained workers needed to operate
- only gives a snapshot of conditions at the time measurements were taken
What are the pros and cons of using living indicator species?
Pros:
- relatively quick, cheap and easy to see whether an area is polluted or not
- gives a long term view because organisms change relatively slowly as the environment changes
Cons:
- it isn’t always reliable because their survival can be affected by other factors (e.g. temperature)
How do you use transects to study the distribution of organisms along a line?
- mark out a line in the area you want to study using a tape measure
- collect data along the line
- you can do this by counting the organism that you’re interested in that touch the line
- or you can use quadrats and place them next to each other or at intervals.
