19.5 investigating populations

Question 1

what is the advantage of random sampling?

Answer 1

avoids bias in data to ensure data is reliable

Question 2

what is systematic sampling used for?

Answer 2

forms of gradual change

Question 3

how is random sampling carried out?

Answer 3

1- lay 2 long tape measures at right angles
2- obtain series of random coordinates by random number generator
3- place quadrats in intersection of each pair of coordinates & record the species

Question 4

how is systematic sampling carried out?

Answer 4

1- stretch string / tape in a straight line
2- lay frame quadrat & species within it is recorded
3- move along the line

Question 5

how could abundance be measured in sampling?

Answer 5

% cover
frequency

Question 6

what is the mark-release-capture technique used for?

Answer 6

for motile organisms

Question 7

how is the mark-release-capture method carried out?

Answer 7

1- animals are caught, marked & released
2- individuals are collected randomly after time
3- number of marked individuals recaptured are recorded

Question 8

what are the assumptions with the mark-capture-release method?

Answer 8

• proportion of marked : unmarked in the 2nd sample is same as the whole population
• marked individuals have evenly distributed themselves
• mark is not made in a way that is more visible to predators
• mark / label has not been lost
• few deaths / births
• definite boundary in population