populations and ecosystems Flashcards
what is meant by the carrying capacity
the maximum population size that can be supported by the environment.
what are fugitive species
high reproductive and dispersal rate and poor competition.
what are equilibrium species
control population within a stable habitat-shown on a sigmoidal growth curve.
What happens in the lag phase of a population curve
Period of adaptation or preparation for growth and time for sexual maturity.
What happens in the exponential phase of a population curve
Population increase
As nimbers increase more become available for reproduction as long as no limiting factor effects growth.
The rate cannot be maintained indefinitely because of environmental resistance.
What happens in the stationary phase of a population growth curve
Birth rate equal to death rate
Population reached carrying capacity.
Death phase can then occur e.g for bacteria this could be beacuse of toxic waste.
What are density dependent factors
The more dense a population the bigger the effect usually biotic factors.
What are density independent factors
Factors effecting an individual regardless of population such as temp
Whay is the carbon footprint
Total amount of carbon dioxide attributable to the actions of an individual or product over a year
What does nitrogen have to be converted to to be able to be used by plant
Ammonium or nitrate ions
Name some nitrogen containing compounds that is passed through the cycle
Amino acids
ATP
Bases
Chlorophyll
What happens in nitrification
Ammonium ions oxidised to nitrites by nitrosomonas. Nitrates are then oxidised to nitrates by nitrobacter
What is the chemical formula for nitrates
NO3-
What is the chemical formula for nitrites
NO2-
What happens in nitrogen fixation
An enzyme in some bacteria combines N2 and hydrogen to form ammonia.
Ammonia can be combined with organic acods to form bacterial protein
Azotobacter is a free living bacteroa in soil
Rhizobium live inside root nodules
