CSEC Biology · January 2008 · Paper 2 · Question 2(a)

Students conducted an ecology study on gaseous exchange in pond snails and waterweed. They set up five test tubes (Figure 2) with indicator solution, stoppered, and exposed to light for one hour. Table 1 shows color changes of hydrogen carbonate indicator solution based on carbon dioxide concentration.

Identify ONE tube in which, after one hour, the colour of the hydrogen carbonate indicator becomes yellow and ONE in which the solution becomes purple. In each case explain your answer.

This question uses a figure or table from the paper — you'll see it when you practise.