Quadrats And Transects

Question 1

What is meant by the distribution of organisms?

Answer 1

•where an organism is found
•this is affected by environmental factors e.g. there might be more daisies in the open than under trees as there is more light available

Question 2

What are two ways you study the distribution of an organism?

Answer 2

1)measure how common an organism is in two sample areas using quadrats and compare
2)study how the distribution changes across and area by placing quadrats along a transect

Question 3

What is a quadrat?

Answer 3

A square frame enclosing a known area

Question 4

How could you compare how common an organism is in two sample areas?

Answer 4

1) place a 1m^2 quadrat at a random point within the first sample areas e.g. divide the area into a grid and use a random number generator to pick coordinates and
2)count all the organisms within the quadrat
3)repeats steps 1 and 2 as many times as you can
4) workout the mean of organisms per quadrat within the first sample area
5) repeat these steps in the second sample area
6)finally compare the 2 means e.g. you might find 2 daisies per m^2 in the shade and 22 in the open field

Question 5

Anna counted the number of daisies in 7 quadrats within her first sample area and recorded the following results: 18,20,22,23,23,23,25
Workout out the mean

Answer 5

154/7= 22 daisies per quadrat

Question 6

Ella used quadrats with an area of 0.5m^2 to randomly sample daisies on an open field. The students found a mean of 10.5 daisies per quadrat. The field has an area of 800m^2. Estimate the population of daisies on the field

Answer 6

1) work out the mean number of organism per m^2:
1/0.5= 2
2 x 10.5= 21 daisies per m^2

2) multiply the mean by the total area:
800 x 21 = 16800 daisies on the field

Question 7

How could you use a transect find out how plants are distributed across an area?

Answer 7

1) mark out a line accross the area you want to study using a tape measure
2) collect the data along the line- you can do this by counting all the organisms that you’re interested in along that line or by using quadrats which can be placed next to each other along each line at intervals e.g. every 2m

Question 8

Some students were measuring the distribution of organisms from one corner of a school field to another using quadrats. Calculate the percentage of each organism if the amount of squares covered by organism A is 42 and 47 for organism B

Answer 8

Type A=
(42/100) x 100=. 42%

Type B=
(47/100) x 100= 47%

Question 9

How can you make an experiment with quadrats more reliable?

Answer 9

Add more quadrats to find a more accurate mean or repeat the experiment