define a sample
observations or measurements from a small area which can be sized up represent a larger area
why is a sample so useful?
as it would be almost impossible to count all organisms or plants individually across a whole area
describe 5 ways to capture insects, and why we need to use this specific kind of technique (special word)
- pooters
- sweep net
- kick sampling
- tree beating
- pit fall traps
- we have to use capture recapture techniques as they move around so we cant easily count them
what is the use of a scaling-up method?
and why would you do so
you can make an estimate of a larger area by looking at a smaller sample and its distribution
- it would take too long to count all organisms/plants individually
use of random sampling?
to ensure no bias is present in the results
what is a quadrat?
a square divided into grids where the organisms are then counted
what would you use to measure biodiversity over an area?
- and how would you carry it out
a transect
- place a piece of tape down, and have quadrats at equal intervals across the area
what kind of organisms are the following sample techniques used to trap?
(and brief description how)
a) pooters
b) sweep nets
c) kick sampling
d) tree beating
e) pit fall traps
a) small insects
- suck on a mouthpiece, the insect drops into the test tube
b) larger insects (some can fly)
- large net catches insects
c) insects/small vertebrae in water
- disturbs vegetation in sea bed + collects it with a net/mesh bag
d) inverebraes that live in trees
- hit/shake branches of tree and see what insects fall off the tree + onto white sheet
e) crawling invertebraes: beetles, spiders, slugs
- they drop into hole + cannot run away
- cover hole with roof so trap does not fill with rainwater
what is an invertebrae?
and give an example
any organism that has no back bone (ie. insects)
what is an identification key used for? (and a brief explanation of how it works)
to identify living organisms
- by asking a series of questions about an organism’s characteristics
two types of idenitification keys
- branched key /spider key (like a huffman diagram i guess)
- numbered key / dichotomous key (like a grid thing) - check notes
how do you estimate the total population of an area (using a quadrat)?
mean population (per meters squared) x total area
how do you estimate the population size using a capture-recapture technique?
first sample size x second sample size / number of recaptured marked individuals
when would non-random sampling be used?
when working out how organism distribution varies over distance
describe 4 positive human interactions within an ecosystem
- conservation
- captive breeding
- seed banks
- reducing rate of deforestation
how does conservation imapct biodiversity?
- protects a natural environment to ensure habitats/animals are not lost
- increases their chance of survival
give 4 factor of an area where conservation occurs (and give an example of where)
- nature reserve
eg. - controlled grazing
—> only allowing animals to graze land for a certain period of time, giving plant species time to recover
restricting human access
—> for example by providing paths to prevent plants being trampled
- feeding animals
—> to ensure more organisms survive to reproductive age - reintroduction of species
—> adding new individuals of a species into an area where numbers have decreased significantly, or where species has not survived
what is captive breeding? (give an example)
breeding animals in human-controlled environments (ie. zoo/ aquarium)
what do scientists use captive breeding for?
- create a stable + healthy population of a species
- reintroduce species to natural habitat
positives and negatives of captive breeding?
pos - no predators, veterinary care given, food given = species has a greater chance of survival
neg - difficult to maintain genetic biodiversity (as few breeding partners are available)
- organisms born in captivity may not survive in the wild (e.g. predators may not know how to hunt for food)
seed banks
- what are they an example of
- what is the purpose?
- how are they stored?
- example of a gene bank
- purpose is to backup against the extinction of plant species
- seeds are cleaned, dried, stored in airtight jars
what are the threats of deforestation use on biodiversity within an ecosystem?
- deforestation (wood for building, space) - biodiversity decreases (loss of food source/ home)
how does agriculture affect the ecosystem and biodiversity? 3
- remove hedgerows for more space (loss of habitat for those animals, and reduction in number of plant species)
- pesticides (remove food source for other organisms)
- pesticides accumulate in food chain, killing animals that were not targeted
- herbicides used to kill plants growing where not wanted (reduces num. plant species present, but also removes a source of food/shelter for animals)
why is biodiversity important?
since species are interdependant within an ecosystem, and so removal of one could affect many different species
