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alevel biology question

Hi can someone please help me understand this question , I know the answer is D however how did they come to it

A sample of a starch suspension was tested with iodine solution and the result was a blue-black colour. A second sample of the starch suspension was tested with Benedict’s reagent and the result was a blue colour. A third sample of the starch suspension was mixed with amylase and incubated at 30 oC for 10 minutes and then tested with Biuret reagent.

What was the resulting colour of the third sample?

A blue

B blue-black

C brick red

D purple
amylase is an enzyme so it is a protein. Therefore when tested with biurets (test for protein) it turns from blue to purple
Original post by fluffycloud101
amylase is an enzyme so it is a protein. Therefore when tested with biurets (test for protein) it turns from blue to purple


thank you :smile::smile:

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