Paper 2 Required Practicals

Question 1

6. How would you use random sampling to estimate the population zise of a plant species ?

Answer 1

• create a grid of the area using tape measures
• use a random number generator to generate coordinates
• set down quadrat at coordinates and record number of required species within quadrat
• repeat using many sampling sites
• estimate population size: total area/area sampled x number of plants species counted

Question 2

6. Why would you use a random number generator to determine coordinates ?

Answer 2

To avoid bias and obtain representative results

Question 3

6. What is random sampling ?

Answer 3

Sampling technique in which each sample has an equal probability of being chosen

Question 4

6. What is systematic sampling?

Answer 4

Sampling techniques where there is a fixed , periodic interval between consectuive samples

Question 5

Describe how you would use continuous sampling to investigate the effect of an abiotic factor in the distibution of a plant species

Answer 5

• Create hypothesis on the effect of the change in an abiotic factor on the distribution of a plant species
• Lay tape measure along an area with an ecological gradient
• Place quadrat at start and count number of plants
• Repeat at 5m intervals along the transect
• Record the value of the abiotic factor eg. light intensity at each sampling site
- produce a graph of plant numbers (y) against the abiotic factor (x)

Question 6

7. What is a reaction time

Answer 6

The time taken to respond to changes in the environment

Question 7

7. Describe how you would investigate how practice affect reaction times in humans

Answer 7

Work in partners. One partner places the forearm of their non-dominant hand on the table, with their hand hanging off the edge.
• One partner should hold the ruler between the fingers of the other partner at the 0 mark.
• The partner holding the ruler drops it without any warning, and the other partner should catch the ruler as quickly as possible.
• Record the number level after the ruler has been caught - repeat at least 5 times per person.
• Find reaction times using a conversion table.

Question 8

What other factors could you investigate in this experiment ?

Answer 8

The effect of caffiene or exercise on reaction times

Question 9

What safety precautions should be taken during this experiment ?

Answer 9

Avoid injury from falling ruler