Biology . Digestion.
Breaking down Starch

Answer/Explanation:

Iodine solution turns from a brown colour to black/blue colour in the presence of starch. Benedict's turns from clear blue to brick red in the presence of sugars. Amylase is an enzyme that breaks down starch into sugar, and works best at 37C.

a. Tube A contains 1% starch solution and amylase, at 37C. Therefore, starch will successfully be broken down, meaning iodine will remain brown, and Benedict's will be brick red

Tube B consists of 1% starch solution and boiled amylase, at 37C. Because the amylase has been boiled, the protein will be denatured. This means it will no longer work as an enzyme to break down the starch into sugar. That means the starch will remain. Therefore, iodine will be blue black, and Benedict's clear blue, as there will be no sugar present.

Tube C contains 1% starch solution and amylase, at 20C. This is too low a temperature for amylase to work, therefore, iodine will be blue black, and Benedict's clear blue, as there will be no sugar present through amylase breaking down the starch

Tube D contains 1% starch, amylase at 37C and hydrochloric acid. Hydrochloric acid will also denature the amylase enzyme, meaning Benedict's clear blue, as there will be no sugar present through amylase breaking down the starch

b. Amylase is secreted by the salivary glands as part of the first step in the breakdown of carbohydrates during digestion. Amylase breaks down starch into smaller sugars through hydrolysis. Accompanied with mechanical breakdown by the actions of chewing, the sugars are further broken down into smaller monosaccharides throughout digestion as a source of energy for respiration

c. 37C is the temperature of the human body and the optimal temperature at which most cellular enzymes function, meaning they work most efficiently at 37C.

d. Hydrochloric acid is present in the stomach, making the contents acidic and promoting the breakdown of large food molecules into smaller components.