ecology Flashcards
what is the definition of a habitat
-environment in which an organism lives in
what is the definition of community
a community is the population of all different species that live in the same habitat
ecosystem defintion
both biotic and abiotic parts of an environment and how they interact.
what is the definition of a population
total number of organisms of the same species living in the same geographical area.
what do plants compete with each other for?
- light
- minerals
- water
- space
what do animals compete with each other for?
- food
- water
- mating partners
- territory
what is interdependance?
when all the different species of a community depend on each other.
how do plants rely on other living organisms
plants rely on bees to disperse their pollen
and rely on birds to disperse seeds in their faeces.
if a species disppears from a community, the whole community is affected. without bees what can happen to plants?
without bees lots of plants would be unable to reproduce as they would not get pollenated.
animals which feed on these plants, could run out of food and their populations would fall.
in most communities, populations of different species remain constant. what is this called
a stable community. a stable community is one where all species and environmental factors are in balance so that population sizes remain fairly constant.
biotic factors (living)
competition between species (one species outcompeting other so numbers are no longer sufficient enough to breed could lead to extinction)
availability of food
new predators arriving( prey population can fall or competition can compete with other predators)
new pathogens
abiotic factors
light intensity temperature moisture levels oxygen levels (for aquatic plants) carbon dioxide levels ( for plants) soil ph and mineral content wind intensity and direction
every food chain starts with a :
producer
what do producers do
synthesise complex molecules
producers source of biomass in all communities
glucose- biomass
primary consumers
primary consumers eat producers
secondary consumers
secondary consumers eat primary consumer
food chain
producer- source of all biomass in a community
biomass such as glucose passes down food chain to other organisms
producers synthesise complex molecueles
primary consumers eat the producer
secondary consumers eat the primary consumer
tertiary consumer- eats secondary consumer
what are consumers that kill and eat other animals called
predators
animal that is being eaten
prey
what can be represented by a food chain
feeding relationships within a community
all food chains begin with a producer
a produce synthesisises complex moclecules. producer usually green plant or algae which make glucose by photosynthesis
why is random sampling used
used to compare numbers of organisms in different areas
using a quadrat
a quadrat is a wooden or plastic square
place it on the ground
count numbers of organisms inside the quadrat
can be used to sample plants or slow moving animals
in random sampling where is quadrat placed
random sampling used to compare number of organisms in different areas
quadrat placed in random locations across the area. one way to do this could be to use random numbers to select different locations
count numbers of organisms in each quadrat
move quadrat to a different random location and count number of organisms over there.
do this until you have large number of random locations
how to make results more valid
place the quadrat a large number of times.
whats wrong with only placing the quadrat once
-might not give us a sample that represents the whole area accurately.
must place quadrat large number of times to get valid results.
total population size
total population size=total area/ area sampled x number of organisms of that species counted in a sample.
sampling along a transect line why is it used
used to investigate whether a number of species changes as we move across a habitat. transect- piece of rope or tape measure place the transect line so that it runs across habitat we are looking it. use a quadrat to count number of organisms at intervals on the transect.
we use sampling along A transect, to see
how numbers of species have changed as we move across a habitat
sand dune
species of plant we find on a sand dune change as we move inland from the sea.we can measure this using sampling along a transect.
first place a tape measure on the dune, runnning from the beach inland. now place first quadrat at start of transect and count different plants in the quadrat
move the quadrat closer in land by a set distance such as 2m count number of plants again. keep doing this as we move further inland.
