b9 Flashcards
(24 cards)
habitat definition
the place where an organism lives
population definition
all of the organisms in a given species, that live in the same habitat (at the same place)
community definition
all the populations (of different species) that live together in a habitat
ecosystem definition
interaction of a community of living organisms biotic with the abiotic parts of their environment
biotic meaning
living
abiotic meaning
non-living
competition definition
interactions between organisms or species in which they both try to use the same limited resources
interdependence definition
organisms in an ecosystem depending upon one another, with (complex) relationships between them all
resources that animals compete for (4)
water
food
mates
territory
resources that plants compete for (4)
water
mineral ions
space
light
in a community there are rabbits, and snakes (which prey on the rabbits)
what happens to the population of rabbits when the population of snakes falls?
increases due to having less predators
why can a factor be considered biotic
biotic because it is determined by living organisms
why can a factor be considered abiotic
abiotic factor as it is not influenced by living organisms
abundance definition
refers to how many organisms there are (in a given place)
distribution definition
distribution refers to where the organisms are (in a given area)
what is sampling
measure a subset of the organisms, and use that subset to make predictions about the whole population
why is sampling used
in real life, measuring exactly how many organisms and where would be very time consuming and difficult
what are the two main sampling methods
random quadrat sampling - to measure abundance
transects - to measure how distribution changes
what is a quadrat
quare frames, divided into lots of smaller squares
how would you use a quadrat
for example to measure the abundance of dandelions (in a 100x100m field using a 1x1m quadrat)
place tape measures along the length + width of the field (forming a large grid)
randomly generate x pairs of random coordinates
place quadrats at those coordinates and count how many dandelions are found in each quadrat.
calculate the mean number of dandelions per m^2.
estimate the total population size using our mean number of dandelions per m^2 and the total area of the field
equation for total pop. size using quadrats
(area of field) x (avg. no. of organisms per m^2)
how would you use transects to find the distribution of dandelions in a field stretching from lake to woodland
a transect line (tape measure) is laid out in a straight line between the lake and woodland
x quadrats are placed at regular intervals along the transect line
the abundance of dandelions is measured by counting the number of dandelions in each quadrat along the transect line, (from the lake to the woodland)
repeat this using new transect lines (parallel to the first).
why measure data along multiple transect lines
so that the data gathered is more representative
producer definition
