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Biological molecules

6 A student carried out an investigation using salivary amylase. Six wells (holes) of the same size were cut in a starch agar plate. Each well was filled with the same concentration and volume of amylase solution. An equal volume of buffer solution was added to produce a different pH in each well. The plates were incubated at 25 °C for 24 hours and then covered with iodine solution. The iodine turned the starch blue–black. It was observed that there were clear rings around some wells. The width of these clear rings is shown in the table.


Biological molecules Exam-style questions
pH
Width of clear ring / mm
a The clear rings around some of the wells indicate the activity of the amylase. Explain why.
b Calculate the rate of reaction at pH 7. Give your answer in units of mm h-1.
c The student concluded that the optimum pH for amylase activity was pH 7. This conclusion may not be valid. Explain why.
A) Amylase catalyses the hydrolysis of Starch into sugars. So if the enzyme is breaking down the starch then there will be areas around the wells with no starch.

B) Would need to see the table. You would use the width of the ring generated (in mm) at pH 7 and divide that by 24 (24 hours).

C) There is no control well (without amylase) to prove that the amylase is causing the effect.
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A_zah1
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Original post by HarisMalik98
A) Amylase catalyses the hydrolysis of Starch into sugars. So if the enzyme is breaking down the starch then there will be areas around the wells with no starch.

B) Would need to see the table. You would use the width of the ring generated (in mm) at pH 7 and divide that by 24 (24 hours).

C) There is no control well (without amylase) to prove that the amylase is causing the effect.

thank you sooooo much

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