RP9 Field investigation

Question 1

how would you use random sampling to estimate the population size of a plant species?

Answer 1

• create a grid of the area using tape measures
• use a random number generator to generate coordinates
• set down quadrat at coordinates and record number of required species within quadrat
• repeat using many sampling sites
• estimate population size: area sampled/total area x number of plants species counted

Question 2

why would you use a random number generator to determine coordinates?

Answer 2

to avoid bias and obtain representative results

Question 3

what is systematic sampling?

Answer 3

sampling technique where there is a fixed, periodic interval between consecutive samples

Question 4

what is random sampling?

Answer 4

sampling techniques in which each sample has an equal probability of being chosen

Question 5

describe how you would use continious sampling to investigate the effect of an abiotic factor in the distribution of a plant species

Answer 5

• create hypothesis on the effect of the change in an abiotic factor on the distribution of a plant species
• lay tape measure along an area with an ecological gradient
• place quadrat at start and count number of plants
• repeat at 5m intervals along the transect
• record the value of the abiotic factor e.g. light intensity at each sampling site
• produce a graph of plant numbers (y) against the abiotic factor (x)