ecology - sampling organisms

Question 1

how do scientists determine number of organisms in an area?

Answer 1

sampling. either by random sampling or sampling along a transect

Question 2

what is random sampling used for? + what do you use for it?

Answer 2

compare numbers of organisms in different areas
a quadrat

Question 3

what is a quadrat?
how do we use it?

Answer 3

a wooden or plastic square
place it on the ground and count number of organisms inside the quadrat

Question 4

when is a quadrat used?

Answer 4

to sample plants or slow moving animals

Question 5

when is random sampling used?

Answer 5

when there are 2 conditions to investigate. as it allows us to compare the numbers of different species of plants

Question 6

where is quadrat placed in random sampling? how to do it?

Answer 6

at random locations across the are. use random numbers to select different locations. then count numbers of each organism in the quadrat. keep doing until sampled large number of different locations

Question 7

why do we have to place quadrat in a large number of different locations?

Answer 7

to make sure we get valid results. if we place it once, it won’t gives us a sample to represent the whole area.

Question 8

random sampling is used to estimate total population size

Answer 8

TPS = total area/area sampled x number of organisms of that species counted in sample

Question 9

when is sampling using a transect used?

Answer 9

to see if numbers of species change across a habitat

Question 10

what is a transect? how to use it?

Answer 10

a tape measure or rope. place it to run across habitat then use quadrat and place at intervals of a set distance on transect to count number of species. repeat multiple times to get valid results on how number of species change across a habitat