Quadrats and Transects

Question 1

When should random sampling be used?

Answer 1

When the sampling area is regular i.e.

organisms are mostly evenly distributed.

Question 2

When is a transect line used?

Answer 2

When the sampling site has an

ecological gradient.

Question 3

Outline the procedure to carry out

random sampling.

Answer 3

1. Set up 2 tape measures at right angles on the field.
2. Obtain coordinates using a random number generator.
3. Place the quadrat down at the coordinates using the tape
   measures as a guide.
4. Record the number of the required species in the qudrat.
5. Repeat to take 9 more samples.

Question 4

State the formula to estimate population

size.

Answer 4

Total area / area of quadrat x mean no.

of individuals in a quadrat

Question 5

Why should a random number generator

be used to find the coordinates?

Answer 5

To avoid bias in random sampling

Question 6

Outline the procedure for systematic sampling using a transect line

Answer 6

1. Lay down a transect line along an ecological gradient.
2. Place the quadrat at the ‘0’ end of the tape measure,
   touching the ‘0’ mark with one corner.
3. Record the number of individuals of the required species.
4. Repeat every 5m up the tape measure until the end is
   reached.
5. Plot a graph of ‘number of individuals’ against the
   changing factor

Question 7

State a hazard and safety precaution involved in this

practical.

Answer 7

Certain plants may cause allergic
reactions or cuts, wear gloves when
handling

Question 8

How should organisms on the edge of

quadrats be accounted for?

Answer 8

Select two edges eg. top and right edges.

Organisms on the edge of those 2 edges will be recorded, while others will not.