10.1 Flashcards
define ecosystem
an environment including all the living organisms interacting within it, the cycling of nutrients and the physical and chemical environment in which the organisms are living
define habitat
a place where organisms live
define microhabitat
small area of a habitat
define community
all the populations of all the different species of organisms living in a habitat at any one time
define abiotic factor
the non-living elements of the habitat of an organism
define biotic factor
the living elements of a habitat that affect the ability of a group of organisms to survive there
define biosphere
all of the areas of the surface of the earth where living organisms survive
define biomes
the major ecosystems of the world
define population
group of organisms of the same species living and breeding together in a habitat
define succession
the process by which the communities of organisms colonising an area over time
what is a climax community
a self-sustaining community with relatively constant biodiversity and species range. it is the most productive group of organisms that a given environment can support long term
what is a climatic climax community
the only climax community possible in a given climate
what is a plagioclimax
a climax community that is at least in part the result of human intervention
describe primary succession
empty inorganic surface
opportunist/pioneer species penetrate the rock surface
this traps organic matter and forms humus
then a soil can be established for grasses and ferns to grow
a root system is established
soil layer develops and more water and nutrients become available
larger plants can be supported
as plant diversity increases animal diversity will closely follow
leading to a climax community
give some examples or opportunist/pioneer species
algae, mosses and fungi
what is secondary succession
the development of an ecosystem from existing soil that is clear of vegetation
what causes secondary succession
river shift their courses, fires and floods, human disturbances
what factors effect the speed of succession
temperature
rainfall
underlying soil fertility
what is a microclimate
a small area with a distinct climate that is different to the surrounding areas
what is an edaphic factor
relate to the structure of the soil
what is leaching
the loss of minerals from soil as water passes through rapidly
how may plants be adapted to photosynthesize in low light levels
extra chlorophyll
different ratio of photosynthetic pigments that are sensitive to lower light levels
very large leaves to collect more light
what factors effect water availability
amount of precipitation
rate of evaporation
edaphic factors
if water is cold and fast flowing the amount of oxygen dissolved in the water will…
increase
if water temperature rises and is stagnant the amount of oxygen dissolved in the water will…
decrease
state the 6 main abiotic factors which effect a population
light
temperature
wind and water currents
water availability
oxygen availability
edaphic factors
state 4 main biotic factors which affect a population
predation
finding a mate
territory
parasitism and disease
explain how predator and prey populations are related
as a prey population increases there is more food for predators so after an interval predator population grows too. Eventually the predators will increase to a point where they are eating more prey than what is replaced by reproduction so number of prey will fall and reduce the food supply for predators so they will not produce as many off spring and numbers of predators will decrease allowing abundance of prey to increase
what is a territory
an area held and defended by an animal or group of animals against other organisms
what are density-independent factors and give an example
factors which are the same regardless of the population size
e.g. temperature
what are density-dependent factors and give an example
factors which depend on how many organisms there are in a specific area
e.g. disease
what causes competition
when organisms compete for a resource that is in limited supply
what is intraspecific competition
competition between members of the same species
what is interspecific competition
occurs when different species within a community compete for the same resource
define abundance
the relative representation of a species in a particular ecosystem
define distribution
where a species of organism is found in the environment and how it is arranged
what is uniform distribution
occurs when resources are thinly but evenly spread or individuals of a species are antagonistic to each other (hostile)
what is clumped distribution
herds or groups of organisms that have specific resource requirements clump together where those resources are found
what is random distribution
occurs when there are plentiful resources and no antagonism
what is a quadrat
a square frame divided into sections that you lay on the ground to identify the sample area
what are the limitations of using quadrats
the area you can sample
the randomness of the sampling site (easy bias)
decisions made about whether to include organisms partially covered by the quadrat
what is the individual count
measures the number of individual organisms in an area
what is percentage cover
the area covered by the above ground parts of a particular species
what is the ACFOR scale and what does it stand for
scale for measuring the abundance of a species in an area
A - abundant
C - common
F - frequent
O - occasional
R - rare
what are the limitations of the ACFOR scale
its subjective
no set definitions
species can easily be rated on by how obvious they are instead of how abundant they are
what is a point quadrat and how is it used
a horizontal bar which has long pins at intervals along it. the bar is placed in the area and species in contact with the bar are recorded
what is a permeant quadrat and why is it used
it stays in the same place and it allows data to be collected and compared over large time periods reliably from the same place
what is a line transect
a way of gathering data more systematically, a tape is stretched between 2 points and every individual species that touches the tape is recorded
what is a belt transect
when 2 tapes are laid out and the ground between them is surveyed
how can you build up a clear picture of the animals that live in an area
mark, release and recapture
what are the issues with using a scatter graph to see correlations
don’t always give clear results
human error when drawing
what is the equation for spearman’s rank correlation co-efficient
rs = 1- 6Ed^2 / n(n^2-1)
d = rank difference
n = number of pairs
what are the steps in carrying out a spearman’s rank correlation co-efficient
1 - null hypothesis
2 - rank value
3 - calculate difference in ranks
4 - square differences
5 - substitute into formula
6 - find critical value based on number of pairs of data (n)
7 - if rs is greater than or equal to the critical value you reject the null hypothesis
what is a t-test used for
to determined whether the mean of a variable in one group differs significantly from the mean of the same variable in a different group
what is the difference between a paired and an unpaired t -test
unpaired - looks at whether there is a difference in the means between two separate / independent groups
paired - looks at whether there is a difference in the mean between the same group before and after a change
what is standard deviation
the average amount of variability in your data
what is the equation for s^2 (variance squared)
s^2 = (Ex, - (Ex)^2/n)/n - 1
