Ecosystems 5

Year 10 Topic 2 – Learning Opportunity 5: Sampling with Quadrats.
This learning opportunity has 5 tasks to complete.
Target time: 40 minutes.

By the end of the next two learning opportunities you will be able to: explain how to determine the number of organisms in a given area using raw data from field-work techniques, including quadrats and belt transects.

Key words: quadrat, sample, estimate, random.

Task 1: A quadrat can be used to estimate the number of daisies in a field. Write out the steps for using a quadrat into the correct order. Watch the video to help you.

•Measure the area of the field and the quadrat
•Repeat placing the quadrat multiple times
•Calculate the mean number of daisies in all of the quadrats
•Place the quadrat randomly in the field
•Count the number of daisies in the quadrat
•Use this equation to scale up the mean to account for the whole field
Estimated number of organisms in area = mean number x (area of field ÷ area of quadrat)

Find the answers at the end of the blog.

Task 2: Calculate the mean (average) number of daisies from the data in the table below.

Quadrat123456789
Number of daisies20633026211872

Find the answer at the end of the blog.

Task 3: Calculate the number of daisies there would be in a 200m x 100m field if a 1m2 quadrat was used to gather the data in task 2.

Hint: Estimated number of organisms in area = mean number x (area of field ÷ area of quadrat)

Find the answer at the end of the blog.

Task 1: Answers

1. Measure the area of the field and the quadrat
2. Place the quadrat randomly in the field
3. Count the number of daisies in the quadrat
4. Repeat placing the quadrat multiple times
5. Calculate the mean number of daisies in all of the quadrats
6. Use the equation to scale up the mean to account for the whole field

Task 2: Answers

Mean = (20+6+33+0+26+21+18+7+2) ÷ 9
Mean = 133 ÷ 9 = 14.7 daisies

Task 3: Answers

Estimated number of daisies = mean number x (area of field ÷ area of quadrat)
Mean number = 14.7 (from task 2)
Area of quadrat = 1 m2
Area of field = 200 m x 100 m = 20000 m2
Estimated number of daisies = 13.3 x  (20000÷1)
Estimated number of daisies = 294,000

Task 4: Complete the quiz using the link below.

Quiz

Challenge Task: Complete the exam question below.

Challenge Task: Answers

a) place all of the quadrats randomly in the field (1 mark)
b) 5+2+1+0+4+5+2+0+6+3 = 28 (1 mark) 28÷10 = 2.8 (1 mark)
ci) Area of pitch = 60 m x 90 m = 5400 m2 (1 mark)
Estimated number of daisies = 2.3 x (5400÷1) = 12420 daises (1 mark)
cii) Area of circle = πr2 (1 mark) = 3.14 x 52 = 78.5 m2 (1 mark) 78.5 x 2.3 daisies = 180.55 daisies (1 mark)

End of Learning Opportunity 5