1. Biotic indicators A biotic indicator is a species used to monitor the health of an environment or ecosystem. Cress is grown on cotton wool soaked in liquids of different pH. After so many days, it’s height is measured

2. Prediction What factors do you think affect the growth of cress seedlings? How do you think pH will affect the height of the plants after 5 days?

3. pH Measurement of cress seeds (cm) 12 3 4 5 6 7 8 9 10 Mean 4 10000000000.1 5 2121.5 140001.2 6 0.81.61.1 0000000.46 7 52.5410000001.25 8 0.50.40.200000000.11 9 00000000000 Cress seeds are grown on cotton wool soaked in liquids of different pH 1. What is wrong with this table? 2. What sort of graph should we plot? 3. Was height the best thing to measure? 4.Were the seeds left for long enough? 5.Draw a graph to show this data