Ecology Flashcards
Definition of population
Number of individuals of a species living in a particular habitat at a particular time
Definition of community
All of the individuals of all the species living in a certain habitat at a certain time
Definition of habitat
Place where an organism lives
Definition of ecosystem
All the biotic and abiotic factors that interact with a habitat at one time
Definition of biotic factors
Living factors in the ecosystem
Definition of abiotic factors
Non-living factors in the ecosystem
Examples of biotic factors
Competition, new pathogens, new predator, availability of food (prey), microorganisms
Examples of abiotic factors
Wind direction/intensity, light intensity, water availability, mineral ions, moisture level, nitrogen levels
Why are food chains usually so short?
Not all energy is passed from one trophic level to the next. Only around10% of the energy at each trophic level is passed onto the next. Total amount of energy available eventually becomes too small to support another trophic level.
What causes loss of energy?
Some parts of the organism are inedible so they aren’t eaten (bones, fur).
Some parts of energy are indigestible so egested as faeces.
Energy is lost by excretion (urine).
Heat energy lost by respiration.
Energy lost due to movement.
What do the arrows in food chains represent?
Transfer of energy.
Can a protoctista be a producer?
Yes, it can photosynthesise.
How to estimate the population of an organism using a quadrat?
Calculate area of the habitat. Use 2 tape measures at right angles to make a 10m x 10m set of axes. Use a random number generator to generate pairs of numbers from 1-10. Use these numbers as coordinates and place your quadrat at the coordinates. Measure number of individuals in the quadrat and then repeat 10x (reliable) with different coordinates. Calculate average number of individuals in a quadrat. Calculate how many quadrats (find area of quadrat before) fit in the area of the habitat. Multiple average number of individual in quadrat by how many quadrats fit in the habitat.
Limitations of using quadrat
Can be easy to miss individuals, especially when covered by a different species. Identifying species can be tricky.
What is a quadrat?
A square frame used to measure abundance of organisms in an area.
Why may using the mean number of organisms not be accurate for calculating the number of organisms in the habitat?
Too few quadrats placed.
Sample may not be representative of lawn.
What is nitrogen fixation?
Process of turning Nitrogen gas into nitrates by nitrogen fixing bacteria or lightning
What is nitrification?
Turns ammonium in decaying matter into nitrates. Nitrifying bacteria do this.
What is denitrification?
Nitrates are turned back into nitrogen gas by denitrifying bacteria
What is decomposition (nitrogen cycle)?
Process of breaking down proteins and urea and turning them into ammonia (a nitrogen compound)
What type of plants contain nitrogen fixing bacteria?
Roots of legume plants
Examples of legume plants
Beans
