An Investigation into Factors that affect the action of the Enzyme Amylase

Experiment 1 :- Amylase volume varied

Time (mins)	Tube1	Tube 2	Tube 3	Tube 4	Tube 5
1	++	++	++	++	+
3	++	++	++	+	-
5	++	++	+	-	-
7	++	++	-	-	-
9	++	+	-	-	-
11	++	+	-	-	-
13	++	-	-	-	-
15	++	-	-	-	-
17	+	-	-	-	-
19	+	-	-	-	-
21	-	-	-	-	-

Experiment 2 :- Temperature Varied

Time (mins)	Tube 1	Tube 2	Tube 3	Tube 4	Tube 5
1	++	++	++	++	++
3	++	++	++	++	++
5	++	++	+	++	++
7	++	++	-	++	++
9	++	++	-	++	++
11	++	++	-	+	++
13	++	+	-	-	++
15	++	-	-	-	++
17	++	-	-	-	++
19	++	-	-	-	++
21	+	-	-	-	++

Experiment 3:- pH varied

Time (mins)	Tube 1	Tube 2	Tube 3	Tube 4	Tube 5
1	++	++	++	++	++
3	++	++	++	++	++
5	++	++	+	++	++
7	++	++	-	++	++
9	++	++	-	++	++
11	++	++	-	++	++
13	++	+	-	++	++
15	++	-	-	++	++
17	++	-	-	+	++
19	++	-	-	-	++
21	++	-	-	-	++

Interpret the above results and explain the influence of these three factors on the action of the enzyme amylase on starch.
Are all three experiments fair tests or not?
Explain your answer.