Question

what would be found in the clear area that would not be found in the blue area of starch agar plate after the addition of iodine

Answer 1

Amylase hydrolyzes the polysaccharides like starch into smaller carbohydrates like Glucose.

During Starch hydrolysis procedure, B.subtilis, E.coli, Pseudomonad aeruginosa lines have to be streaked on starch agar plates. Then these plates have to be incubated in inverted position at 35 degrees Celsius for 24 hours.

After 24 hours, if any bacterial growth is there, then it has to be recorded and then the plate has to be flooded with gram's iodine. The areas, where starch hydrolysis has occurred, those areas appear clear. And the areas, where starch hydrolysis has not occurred, those areas will appear dark blue in colour.
Thus, glucose is found in the clear area as starch has got hydrolyzed by amylase.

And in the blue area starch is found and as it is not hydrolyzed by amylase and it could give blue color with iodine solution.