Unit 3 - KA2 Distribution of Organisms Flashcards
What is an abiotic factor?
Abiotic factors are non living variables that can influence where organisms can live.
What are some examples of abiotic factors?
-Light intensity
-Temperature
-pH
-Moisture
What is a biotic factor?
Biotic factors are the living components that shape an environment
What are some examples of biotic factors?
-Food availability
-Competition for resources
-Predation
-Disease
-Grazing
Common errors of a light meter and how to minimise them?
-Shading the light meter - Avoid shading the light meter
-Light intensity may change due to cloud cover - Take all measurements at the same time of the day
Common errors of a moisture meter/pH meter and how to minimise them?
-Not cleaning the probe between readings - Clean the probe between readings
-Not pushing the probe deep enough into the ground - Push the probe deep into the ground
-Not taking enough samples - Take more samples
Common errors of a thermometer or temperature probe and how to minimise them?
-Not giving enough time for alcohol to fully rise/fall - Allow them to stabilise before taking a reading
-Not taking enough samples - Take more samples
What is a quadrat?
-Marks off an extract area so that the plants in that area can be identified and counted
-Is used to estimate the abundance of plants or slow moving animals
How to calculate abundance?
Calculate the number of squares occupied by a particular species, only count if more than 50% of the organism is in the quadrat section
Quadrat errors and how to minimise?
-Too few samples taken - Take more samples
-Non random placement of quadrat - Ensure random placement of quadrat
-Deciding whether the sample is “In or out” - Only count the square if more than half of the plant is in the square
What are pitfall traps used for?
Used to sample the small invertebrates living on the ground
Pitfall trap errors and how to minimise?
-Sample may not represent the whole ecosystem - Take more samples
-Birds may eat trapped animals - Disguise the opening
-Some animals may eat others - Check trap regularly or use a preserving liquid (alcohol)
Effects of grazing on biodiversity?
-Grazing is the eating of green plants by herbivores
-Grazing animals have an effect on biodiversity of plant species
Effect of predatation on biodiversity?
Predators reduce the number of their pray and in extreme situations this can result in extinction of the pray species
What are indicator species?
Indicator species are species that by their presence or absence indicate environmental quality and levels of pollution
