7.) Here are 7 experimental conditions from a digestion experiment. The incubati

Question

7.) Here are 7 experimental conditions from a digestion experiment. The incubation lasted 1 hr. 5 Amylase Amylase Amylse I. water D.I. water Amylase Amylase Maltose Starch pH7.0 pH 2.0 pH 9.0 Starch Starch D.I. water Starch Starch pH7.0 pH 7.0 pH 7.0 pH 7.0 Boil first, then incubate at 37°C KI test Benedict's Test For each condition give the expected result. You should be able to explain why the result is expected What do tubes 2, 6 and 7 reveal about pH and amylase activity? Which pH buffer allowed the highest amylase activity? Would salivary amylase be active in the stomach? Which tube indicates that the amylase was not contaminated with maltose? Which tubes indicate that the deionized water did not contain contaminating starch or maltose? If we left out control tubes 3,4 or 5 what objections could be raised to the statement "Amylase digests starch to maltose?

Explanation / Answer

tube 1 and tube 2:Amylase+ Starch+ pH 7:iodine test and Benedict test positive. because amylase digest the atrch completely and produced maltose. because pH is optimum.

tube 3:Amylase + deionized water + PH 7.00 buffer; the iodine test was negative and

Benedict’s test was also negative. The results were predicted since the tube did not contain any

starch in first place and thus the iodine test was negative. The negative results of Benedict’s test

show that neither the amylase solution nor the deionized water is contaminated with maltose or

starch.

tube 4:

deionized water + starch + PH 7.00 buffer; the iodine test was positive and Benedict’s

test was negative. The tube did not contain amylase enzyme and thus no maltose was produced

and that is why only the iodine test was positive since it detected the undigested starch. The

negative results of Benedict’s test confirm that the deionized water is not contaminated with

maltose.

tube 5:

deionized water + maltose + PH 7.00 buffer; the iodine test was negative while the

Benedict’s test was strongly positive (red color). The tube did not contain any starch and that is

why the iodine test was negative. On the other side, the tube already contained maltose and this

led to the strong positive result of the Benedict’s test. The negative result of iodine test confirms

that the deionized water is not contaminated with starch.

tube 6:

Amylase + starch + PH 2.00 buffer; the iodine test was positive and Benedict’s test was

weakly positive (green color). These results show that the amylase enzyme digested the starch

incompletely producing some maltose molecules. This is why the iodine test detects the

remaining undigested starch and the Benedict’s test detects the small amount of maltose

produced. The enzyme did not function properly since it was placed in a PH, which is not

optimum (2.00) while the optimum PH is 7.00. These results confirm that the amylase optimum

PH is 7.00. It also shows that the enzyme would be poorly function in an acidic PH.

tube 7: amylase+ starch + pH 9 - iodine and benedict test will be positive. but digestion will not be completed. because the pH is increased.

ques 3. 7 pH buffer allows highest amylase activity.

ques 4. salivary amylase cannot function in stomch . because stomach pH is 1.5-3.5. it is not optimum for amylase activity.

ques 5: tube 3

ques 6:tube 4 and tube 5

ques 7: in tube 3 and tube 4 Benedict test was negetive because didnot contain starch and Amylase respectively in the first place. but in tube 5 Benedict is +ve due to maltose but there was no Amylase. this raised the statement that to produce maltose , amylase has to be present to digest the starch.

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