Procedure for page 34 (Hands-on)

Procedure:
1. 6 test tubes were labelled as A, B, C, D, E and F and put in a water bath at 37oC.
2. Each test tube was filled with different volumes of saliva and distilled water as given.
3. A few drops of iodine were dropped separately on the grooves of a white tile.
4. 4 ml of starch solution was poured into test tube A.
5. The stopwatch was started. A small amount of mixture was added to the drop of iodine on the white tile immediately.
6. The colour change in iodine was observed.
7. The iodine test was carried out at an interval of 30 seconds until there was no more change in iodine colour (colour remained yellow).
8. The time taken when the colour of iodine remained yellow was recorded.
9. Steps 4-8 were repeated for test tubes B, C, D, E and F.
10. All observations were recorded.
11. A graph of rate of reaction (1/time) against enzyme concentration was plotted.