populations in ecosystems Flashcards
what is a species?
a group of organisms that share a gene pool and have similar characteristics and can breed to produce fertile offspring
what is a habitat?
the place in which an organism lives
what is a population?
a group of organisms of the same species living in the same habitat at the same time
what is a community?
all of the populations of different species that interact in the same habitat
what is a niche?
describes how an organism fits into its environment - where it lives and what it does there. it includes the biotic and abiotic conditions to which an organism is adapted in order to survive and reproduce
what is an abiotic factor?
non living components of the environmentw
what are some examples of biotic factors?
food availiability, prey, predators, competition, available mates
what is a biotic factor?
living components of the environment and their interactions
what are some examples of abiotic factors?
humidity, temperature, wind speed, light intensity, soil pH
what is an ecosystem?
a dynamic system made up of a community and all of the interacting biotic and abiotic factors in that area
what is carrying capacity?
the maximum population size that can be supported by the ecosystem
what is the lag time on a growth curve showing?
- there is slow replication
- getting used to conditions (e.g. by making enzymes)
what is the log time on a growth curve showing?
- fast replication
- optimum conditions (e.g. lots of oxygen, glucose)
what is the stationary phase on a growth curve showing?
- little/no replication
- lack of glucose/oxygen
- too high temp / wrong pH
what is the carrying capacity?
the maximum population size that can be supported by an ecosystem
what are the two types of competition?
interspecific and intraspecific
what is interspecific competition?
competition between different species
why is it important to sample randomly?
to avoid any bias
how would you make a sample more representative?
by using more quadrats
what are the two ways of measuring abundance?
- frequency
- % cover of area
what is the method for random sampling?
1/ divide sampling area into a grid and use a random number generator to give coordinates
2/ at each coordinate place the quadrat and record the %cover of plantain in the quadrat (can be changed for number of the organism)
3/ repeat for 20 quadrats and calculate a mean
4/ multiply the mean by the number of quadrats that would fit into the whole field
when would you use a transect?
used to study the DISTRIBUTION of a species
if we think an abiotic factor changes across a habitat and this affects the living species
how to carry out a practical with a transect?
lay a tape measure across the habitat and at set intervals place the quadrat down and record the number/%cover of a species
at each sampling point also record the abiotic factor
repeat 2 more times parallel to the first transect
summarise the relationship between predators and prey?
- predators eat prey , reducing pop size
- fewer prey available , so more competition between predators
- predator pop reduced as some unable to get prey
- fewer predators left , soprey pop size increases
- more prey available , so predator pop size increases
what are confounding variables?
variables that we cannot control, but it may affect our dependent variable
what are examples of confounding variables in sampling practicals?
soil ph, temperature, soil moisture content
