B7 Using Transects (page 88) Flashcards
What do you use Transects to study?
The distribution of organisms along a line.
Why can you use Transects?
to help find out how organisms (like plants) are distributed across an area.
Explain how you would find out if an organism becomes more or less comon as you move from a hedge towards the middle of a field?
1) Mark out a line in the area you want to study using a tape measure
2) Then collect data along the line
3) You can do this by just counting all the organisms you’re interested in that touch the line.
4) Or, you can collect data by using quadrats (see previous page). These can be placed next to each other along the line or at intervals, every 2 m. (see picture example on page 88)
Can Transects be used in any ecosystem, or just fields?
Transects can be used in any ecosystem, fields, along a beach…
You can estimate the percentage cover of a Quadrat, exaplin why?
If it’s to difficult to count all the individual organisms in the quadrat (e.g. if they’re grass) you can calculate the percentage cover.
How do you calculate the percentage cover of an area of the quadrat by a particular type of organism?
by counting the number of little squares covered by the organisms.
Look at diagram 2 on page 88.
Some students were measuring the distribution of organisms from one corner of a school playing field to another, using quadrats placed at regular intervals along a transect.
Look at the picture of one of the quadrats. Calculate the percentage cover of each organism, A and B
1) Cout the number of squares covered by organism A
Type A = 42 squares
2) Make this into a percentage - divide the number of squares covered by the organism by the total nmber of squares in the quadrat (100), then multiply the result by 100
(42/100) x 100 = 0.42 x 100 = 42%
3) Do the same for organism B
Type B = 47 squares
(47/100) x 100 = 0.47 x 100 = 47%
What is a transect? (1 mark)
A line used to help find out how organisms are distruibuted across an area ( 1 mark)
Some students want to measure how the distribution of dandelions changes across a field, from one corner to another. Describe a method they could use to do this? (2 marks)
They could mark out a line across the field, from one corner to the other (1 mark). Then they could count all of the dandelions that touch the line (1 mark).
How could you estimate the number or organisms in a quadrat, if they are difficult to count? (1 mark)
You could estimate the percentage of the quadrat covered by the organisms (1 mark)
