investigating populations

Question 1

describe how you would do random sampling

Answer 1

-place a grid using two measuring tapes at right angles to form axis
-use a random number generator to make random coordinates to place your quadrats on for the grid.
-calculate abundance by suing one of the three methods : density; frequency ; percentage cover

Question 2

when estimating you need to …

Answer 2

-ensure the data collected is not biased and was selected at random
-make sure sample size is large enough so its reliable, representative and suitable for a statistical analysis (more than 20) so after a while the running mean shows little/no change.
-make sure the method of collection of samples must also be appropriate to the species (e.g quadrating is suitable for very slow moving organisms)
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Question 2

when estimating you need to …

Answer 2

-ensure the data collected is not biased and was selected at random
-make sure sample size is large enough so its reliable, representative and suitable for a statistical analysis (more than 20) so after a while the running mean shows little/no change.
-make sure the method of collection of samples must also be appropriate to the species (e.g quadrating is suitable for very slow moving organisms)
-

Question 3

how can you check to see if an investigation is reliable

Answer 3

-repeat it couple of times
-if other scientists repeat it and get similar results to you

this makes a more reliable mean

Question 3

how can you check to see if an investigation is reliable

Answer 3

-repeat it couple of times
-if other scientists repeat it and get similar results to you

this makes a more reliable mean

Question 4

describe the mark-release-capture method

Answer 4

-animals of a particular species are collected (usually by netting/trapping) and counted
-they are then marked in some way that does not affect ability to feed or increase chance of predation ( paint dots, UV dye tagged)
-then are released and left to redistribute into their population.
-after a reasonable time (hrs/days/weeks) a second capture is carried t and the total number of caught is recorded, aswell as how many of those released and recaptured were previously marked.

Question 5

explain how selection occurs in living organisms.

Answer 5

-variation due to mutation
-different abiotic/biotic conditions
-leads to a selection in advantageous alleles
-differential reproductive success- the selected organisms survive and reproduce.
-so allele frequency increases over a period of time