11.2 Types Of Sampling

Question 1

Define sampling

Answer 1

Taking measurements of a limited number of individual organisms present in a particular area

Question 2

Define distribution

Answer 2

The natural geographic range of an organism

Question 3

Define abundance

Answer 3

The number of individuals of a species present in an area

Question 4

What is random sampling?

Answer 4

Selection of individuals by chance

Question 5

Explain how random sampling is done.

Answer 5

1. Mark out a grid on the grass using 2 tape measures laid at right angles
2. Use random numbers to determine the x coordinate and the y coordinate on your grid
3. Take a sample at each of the co-ordinate pairs generated

Question 6

What is opportunistic sampling?

Answer 6

Using samples that are conveniently available

Question 7

What is the problem with opportunistic sampling?

Answer 7

Often not representative of the population

Question 8

What is stratified sampling? (Explain how it is done)

Answer 8

• Population is divided into strata (groups)
• A random sample is taken from each strata, proportional to its size

Question 9

What is systematic sampling? (Explain how it is done)

Answer 9

• Transect is used to systematically sample along the transect line/environmental gradient
• Samples taken at regular intervals

Question 10

When is systematic sampling used?

Answer 10

When the study area includes an environmental gradient

Question 11

What is a belt transect?

Answer 11

2 parallel transect lines

Question 12

What biotic factors affect abundance and distribution?

Answer 12

• Competition
• Predation
• Food availability
• Herbivore abundance