Question

Observations. Indicate whether each test was positive or negative and indicate what color each solution was after performing the tests. Describe what caused the observed results in the Benedict's Test for starch/saliva vs. starch buffer mixtures. Describe what caused the observed results in the iodine test for the starch/saliva vs. starch/buffer mixtures.

Answer 1

Benedicts test

Starch saliva - Blue to green, yellow and brick red

Starch buffer - blue

Starch is polysachharide without any reducing sugar present in it.

Whereas benedicts reagent gives positive test with reducing sugar only. When starch is kept with buffer there is no reducing monosachharide sugar present in it and hence negative benedicts test. Blue color.

When starch and saliva are kept, amylase enzyme of saliva digest starch into monosachharides which geta reduced by bendicts reagent to give blue to green to yellow to brick red acoording to amount of starch.

Same as iodine test

Starch buffer - blue black, negative iodine test

Starch salive - brown color - positive iodine test by monosachharide sugars

Answer 2

Some were positive and some were negative starch saliva was blue to green yellow and brick red