7. Ecology (required practical 9 - sampling organisms)

Question 1

What are the steps for measuring the population size of a common species in a habitat?

Answer 1

1. First place two tape measures at right angles, which should both be 20m in length
2. Then get two bags, with each bag containing the numbers 1 to 20
3. The student should be in a group of three, and the first student should pick a number from the bag, whatever number is picked represents a metre on one of the tape measures in which the student has to stand at
4. The second student should select a number from their bag and move to that point on the other tape measure
5. The third student should place a quadrat on the ground at the __m by __m point
6. The students then record the number of daisies in the first quadrat
7. The students then return their numbers back to the bag and repeat this process nine more times for a total of 10 samples
8. Use the equation to estimate the total population of daises in the whole field.

Question 2

What is the size of the quadrat in this case?

Answer 2

0.5 x 0.5m

Question 3

What do you need to be careful of in the real exam?

Answer 3

Make sure you change your memorized answer to fit what the question asks specifically

Question 4

If there are more/less than average of a species in a particular area, what should you do?

Answer 4

• increase/decrease the number of quadrat throws to cover a greater/smaller percentage of the area

Question 5

How do you measure the effect of light intensity on the distribution of daises?

Answer 5

1. Place a tape measure at the tree
2. Use a quadrat to count the number of daisies at the start of the transect, and record the light intensity at this point using a light meter or an app
3. Move the quadrat 1m down the tape measure and repeat the measurements
4. Continue doing this all the way down the tape measure

Question 6

What is a transect line used for?

Answer 6

to see how the number of daises changes from the tree outwards

Question 7

Why is it possible that a greater number of daises will be seen as you move further from the tree?

Answer 7

as under the tree there will be a lower light intensity and trees absorb lots of mineral ions from the soil