1.
Enzymes are usually ____________ in nature.
Correct Answer
D. Protein
Explanation
Enzymes are usually proteins in nature. Proteins are large molecules made up of amino acids and they play a crucial role in biological processes. Enzymes are a specific type of protein that act as catalysts, speeding up chemical reactions in the body. They are involved in various metabolic processes, such as digestion, energy production, and DNA replication. Enzymes have specific shapes that allow them to bind to substrates and facilitate chemical reactions. Therefore, the correct answer is protein.
2.
Which of the following statements regarding enzymes is NOT true?
Correct Answer
B. An enzyme can still function if the shape of its active site is altered.
Explanation
The substrate cannot bind to an enzyme if the shape of the active site is altered.
3.
Which of the following is NOT an example of an enzymatic reaction?
Correct Answer
D. Emulsification of fats
Explanation
The breakdown of proteins into polypeptides in the duodenum involves proteases. Curdling of milk in the stomach involves the enzyme, rennin. Cellulose is digested by cellulase. Emulsification is a process whereby fats are broken down into tiny fat droplets (physical process).
4.
Under which conditions would salivary amylase act on a solution of starch most rapidly?
Correct Answer
C. pH 7, 25°C
Explanation
Enzymes denature at high temperatures. Optimum pH of salivary amylase is pH 7.
5.
What are the products formed from the breakdown of oil by lipase?
Correct Answer
B. Fatty acids and glycerol
Explanation
Lipase is an enzyme that breaks down lipids, such as oil, into their components. Fatty acids and glycerol are the products of this breakdown process. Therefore, when oil is broken down by lipase, it forms fatty acids and glycerol.
6.
What is the enzyme found in potato that is able to react with hydrogen peroxide?
Correct Answer
B. Catalase
Explanation
Catalase is the correct answer because it is an enzyme found in potato that is able to react with hydrogen peroxide. Catalase is responsible for breaking down hydrogen peroxide into water and oxygen, which helps protect the potato from oxidative damage. Amylase, lipase, and protease are enzymes that have different functions and are not involved in the reaction with hydrogen peroxide.
7.
Which of the following are characteristics of enzymes?
1. Enzymes are highly specific.
2. Enzymes remain unchanged at the end of their reactions.
3. Enzymes are required in large amounts.
Correct Answer
A. 1 and 2 only
Explanation
Enzymes can be used over and over again. Hence, only a small amount of enzyme is required to catalyze a large number of chemical reactions.
8.
Which of the following enzymes works well when it is mixed with distilled water?
Correct Answer
A. Salivary amylase
Explanation
Salivary amylase works well when mixed with distilled water because it is an enzyme that breaks down carbohydrates, specifically starches, into simpler sugars. Salivary amylase is produced in the salivary glands and is present in saliva. When mixed with distilled water, it can effectively catalyze the hydrolysis of starch molecules into maltose and dextrin. This is because distilled water provides an optimal environment for the enzyme to function, without any interference from other substances that may inhibit its activity.
9.
Which of the following statements about enzymes is NOT correct?
Correct Answer
C. Enzymes break down complex substances only.
Explanation
Some enzymes are involved in anabolic reactions.
10.
According to the 'lock and key' hypothesis, what is represented by the lock and key?
Correct Answer
A. The lock represents the enzyme while the key represents the substrate.
Explanation
In the 'lock and key' hypothesis, the lock represents the enzyme while the key represents the substrate. This analogy suggests that the enzyme (lock) and substrate (key) have complementary shapes that fit together specifically. Just as a key can only fit into a specific lock, a substrate can only bind to a specific enzyme. This interaction between the lock (enzyme) and key (substrate) is essential for the enzyme to catalyze a specific chemical reaction.