Populations and Ecosystems P1 Flashcards
what is a population?
a group of organisms of the same species living in the same habitat
what is a habitat?
the part of an ecosystem where an organism lives
what is a community?
all the populations of different species living in the same habitat at the same time
what is an ecosystem?
a community of all living and non living components of an environment (the biotic and abiotic factors)
what is a niche?
the role of a species within an ecosystem and their habitat, including their position in the food web and what they eat. no two species can have the same niche
what is the carrying capacity?
the maximum population size an ecosystem can support
what are the abiotic factors?
the non living features of an ecosystem eg the temperature and the water availability
what are the biotic factors?
the living factors eg. the presence of predators and food
the niche a species occupies within a population includes what?
its biotic interactions - what it eats and what its eaten by
its abiotic interactions - eg the oxygen it breaths in and the co2 it breaths out
what is a species?
organisms that can interbreed to produce fertile offspring
give 6 examples of abiotic factors
- temperature
- oxygen
- carbon dioxide concentration
- light intensity
- pH
-soil conditions
what is an adaptation?
a feature that increases an organisms chance of survival and reproduction
state and describe the three types of adaptation
behavioural = the way the organism acts, such as migrating to find food
physiological = internal biological functions helping the organism survive
structural = features of an organisms body that help it survive
by what process do adaptations develop?
natural selection
explain how natural selection increases an organisms chances of survival
- organisms better adapted to the environment are more likely to survive and reproduce
- by doing this, they will pass on their alleles
- thus, the frequency of this allele will become increase within the population
give two examples of biotic factors that can affect population size
competition and predation
what is interspecific competition?
when members of different species compete for the same resources that are in limited supply.
(the individual better adapted to the environment is more likely to succeed in the competition)
what is intraspecific competition?
when members of the same species compete for resources and a mate. (individuals that are fitter, have more energy or are in better condition are more likely to attract the mate)
state 4 things that species may compete for
- space
- food
- water
- a mate
what is the general strategy for taking a random sample?
- chose a random area to sample to avoid bias by dividing the field into a grid, and then using a random number generator to select coordinates
- chose an appropriate technique to take a sample (eg. quadrats or transects)
- repeat the process, taking as many samples as possible (reducing the likelyhood results are down to chance)
- number of individuals in the whole area can be estimated by taking a mean of the data in each sample and then multiplying it by the size of the whole area
describe the population relationship between predators and prey
- as the prey population increases, theres more food for the predators, so the predator population increases.
- however, as the predator population increases, more prey is eaten, so the prey population begins to fall.
- this means theres less food for the predators, so their population decreases too.
how to ensure samples accuratley represent the population?
random sampling in uniform areas to eliminate bias
- line transects to examine a change over distance
- a large number of samples (30+) to ensure your accuratley representing the population
when is it appropriate to use a quadrat?
- when the sample contains slow/non moving organisms
- when the organisms are uniformly distributed in the area
when do we use a line transect?
- when there is uneven distribution of organisms in the area (populations that change over distance)
- when the sample contains slow/non moving organisms