Experiment+-+The+Effect+of+Temperature+and+pH+on+Enzyme+Action

//Table 2 - Results of starch digestion using amylase in different pH//
 * < **Test tube** ||< **Contents** ||< **Iodine Test: 0min** ||< **Iodine Test: 10min** ||< **Conclusion** ||
 * < W ||< 2cm3 of starch solution + 2cm3 of HCl + 2cm3 of amylase ||< Solution turned blue-black ||< Mixture turned blue-black ||< Enzymes cannot function in very low pH ||
 * < X ||< 2cm3 of starch solution + 2cm3 of distilled water + 2cm3 of amylase ||< Solution turned brown with traces of blue black ||< Mixture turned brown with traces of blue-black ||< Enzymes work well in neutral pH ||
 * < Y ||< 2cm3 of starch solution + 2cm3 of NH4OH + 2cm3 of amylase ||< Solution turned blue-black ||< Mixture turned blue-black with traces of brown ||< Enzyme action is little when pH is high ||
 * < Z ||< 2cm3 of starch solution + 4cm3 of distilled water ||< Solution turned blue-black ||< Mixture turned blue-black ||< Starch is not broken down as enzymes were not added to the solution ||

Test-tube X, as the iodine solution turned brown with traces of blue-black when added to the mixture, indicating that there is little starch left in the mixture, and hence showing that amylase has broken down the starch.
 * INTERPRETING THE RESULTS**
 * 1. Which test-tube shows that starch digestion has occurred? Give your reasons.**

Test-tubes W, Y and Z.
 * 2. Which of the test-tubes contained mixtures that gave a blue-black colour?**

For tubes W and Y, they remained blue-black as the pH conditions of the mixtures were not suitable for amylase to carry out starch digestion. For tube Z, it is a control setup and hence the starch is unaffected.
 * 3. Why did the mixtures in tubes stated in (2) remain blue-black?**

Extreme pH (too high or too low) causes enzymes to be unable to function.
 * 4. What conclusion(s), based on the observations in this experiment, can be made about the effect of pH on enzyme action?**

A2: amylase solution || 0 degrees Celsius || Mixture turned blue-black with traces of brown || Enzyme action is reduced with low temperature || B2: amylase solution || 37 degrees Celsius || Mixture turned brown with traces of blue-black || Enzyme action is high || C2: amylase solution || 100 degrees Celsius || Mixture turned blue-black || There is almost no enzyme action as the temperature is too high for enzymes to function || (control setup) || D1: starch solution D2: distilled water || 37 degrees Celsius || Mixture turned blue-black || Starch is not broken down as enzymes were not added to the solution || //Table 1 - Results of starch digestion using amylase at different temperatures//
 * PART 1**
 * **Test tube** || **Contents** || **Temperature** || **Iodine Test** || **Conclusion** ||
 * A1 || A1: starch solution
 * B1 || B1: starch solution
 * C1 || C1: starch solution
 * D1

Tube B1, as the iodine solution turned brown with traces of blue-black when added to the solution, indicating that there is little starch left in the solution. This shows that the amylase in the tube has broken down the starch**.
 * INTERPRETING THE RESULTS**
 * 1. Which tube shows that starch digestion has occurred? Give your reasons.**

2. Which of the test-tubes contained mixtures that gave a blue-black colour?** Test-tubes A1, C1 and D1.

For tubes A1 and C1, they remained blue-black as the temperature was too low and too high respectively for amylase to function properly and digest starch. For D1, however, no amylase was present to break down starch so the starch was unaffected.
 * 3. Why did the mixtures in tubes stated in (2) remain blue-black?**

It served as a control.
 * 4. What purpose did the tube D1 serve?**

I would use Benedict's Test for reducing sugars, as starch should be broken down into monosaccharides which are reducing sugars.
 * 5. Using your knowledge of the structure of starch, describe the test you would use to detect the presence of the substance produced as a result of the reaction in test tube stated in (1) above.**

Extreme temperatures (too high or too low) causes enzymes to be unable to function.
 * 6. What conclusion(s), based on the observations in this experiment, can be made about the effect of temperature on enzyme action?**