While testing amylase activity, john uses a buffer of ph 6 and substrate starch. he incubates them at 104ºf (40ºc). all the tubes show glucose formation, except one, which had no starch solution. why did this happen?

the optimum ph for the enzyme amylase is not ph 6.
the optimum temperature for the enzyme amylase is not 104°f (40°c)
the substrate for amylase, starch, is not present.

Option C, The substrate for amylase, starch, is not present.

Explanation:

All the tubes (except one) were exposed to following three conditions -

a) a buffer of pH 6

b) a temperature of 104ºF (40ºC)

c) presence of starch

The only tube which was exposed to  first two conditions but not the third one i.e starch,  do not produce glucose because starch (substrate) was not available for enzyme amylase on which it can act upon under favorable conditions.

The reaction will start only when the enzyme meets the starch.

b.have there own function.