Practicals (Paper 2)

Question 1

What is the method for carrying out an experiment to measure how light intensity affects the rate of photosynthesis?

Answer 1

• Place 20 algal balls and the same volume of indicator solution in each tube
• Check the colour of the indicator against the pH chart and record the starting pH
• Use the metre ruler to place the tubes at specific distances to lamp
• Leave the tubes for one or two hours and then record the pH and the distance
• Calculate the rate of change in pH per hour

Question 2

What is the method for quadrat sampling?

Answer 2

• Place quadrats randomly within an area and measure the amount of organisms in that quadrat
• Make an estimate of the total number of organisms in the area using the equation: total number of organisms in an area = number of organisms in one quadrat x (total area / area of one quadrat)