Question
The equation shows the digestion of protein to amino acids.
In the equation, what is protease?
(A) a catalyst
(B) a product
(C) a solvent
(D) a substrate
▶️Answer/Explanation
Ans: A
The correct answer is A (a catalyst), because:
Protease is an enzyme (proteins that function as biological catalysts), which is also called as catalyst (A substance that increases the rate of a chemical reaction but it doesn’t alter).
Whereas,
- Product (Amino acids) is the result of substrate (protein) and catalyst (proteases)
- Solvent is the dilutent used to add to solute to reduce its concentration
- Substrate (proteins) is the raw substances used in reaction with desire of achieving something as product.
Question
What is a correct statement about biological molecules?
A Biuret reagent is used to test for reducing sugars.
B Glycogen is made of smaller glycerol molecules.
C Oils contain the chemical elements carbon, hydrogen, oxygen and nitrogen.
D Protein is made of smaller amino acid molecules.
▶️Answer/Explanation
Ans D
The correct answer is D (Protein is made up of smaller amino acid molecules), because:
Proteins are made up of long chain of amino acids chemically bonded together. About 20 different amino acids are present with complex pattern and large molecules.
- Biuret teest is used to test proteins, whereas reducing sugars are tested by Benedict’s test.
- Glycogen is a large carbohydrate , which is made up of glucose as sub units but not glycerol molecules.
- Oils contain Carbon, hydrogen, oxygen but not nitrogen (its present in protein)
Question
DCPIP can be used to test for vitamin C in food. Lemon juice contains vitamin C. When lemon juice is tested with DCPIP what are the results?
(A) starts blue, finishes colourless
(B) starts colourless, finishes blue
(C) stays blue
(D) stays colourless
▶️Answer/Explanation
Ans A
The correct answer is A (Starts blue, finishes colourless), because:
DCPIP is a deep blue colour initially, which becomes colourless on exposure to vitamin C present in fruit juice.
Question
Which chemical is used to test for the presence of protein in a food sample?
(A) Benedict’s solution
(B) biuret solution
(C) DCPIP
(D) iodine solution
▶️Answer/Explanation
Ans: B
Biuret test is done to test protein in a food sample.
- Benedict test done for Reducing sugars
- DCPIP is done for vitamin C
- Iodine solution is done for Starch