All Free Biology MCQs with Answers

1521. I can break down fatty acid to succinate__________?

• A. Peroxisome
• B. Glyoxisome
• C. Lysosome
• D. Golgi bodies

Explanation: Glyoxisomes contain enzymes of the glyoxylate cycle, which allows plant cells to convert fatty-acid products into succinate and other compounds. Peroxisomes also participate in fatty-acid breakdown, so students may choose them, but the conversion toward succinate is specifically associated with glyoxisomes.

1522. Co-enzyme is often formed from ?

• A. lipid
• B. protein
• C. inorganic ion
• D. vitamin

Explanation: Many coenzymes are organic, non-protein helpers derived from vitamins, and they assist enzymes by carrying electrons or chemical groups during reactions. An inorganic ion may be chosen because some enzymes require mineral cofactors, but an inorganic ion is a cofactor rather than a coenzyme.

1523. Enzyme discovered by: ___________?

• A. Jons Jacob Berzelius
• B. Anselme Payen
• C. Walter Bradford Cannon
• D. None of these

Explanation: Anselme Payen and Jean-François Persoz discovered diastase, one of the first recognized enzymes, in 1833. Jöns Jacob Berzelius proposed the term enzyme-related 'catalytic force' but was not credited with discovering an enzyme, so students may choose him because of his early theoretical work.

1524. Like enzymes , co enzyme can be used ?

• A. only once
• B. only few times
• C. again and again
• D. non of above

Explanation: A coenzyme functions as an organic helper molecule and is usually regenerated or transferred back to its original form during enzyme reactions, allowing repeated use. Students may choose only once because they confuse a coenzyme's participation in one reaction cycle with permanent consumption.

1525. Enzyme activity can also be charted through the __________ ?

• A. Rate of digestion
• B. Rate of reaction
• C. Level of pH
• D. Number of active sites

Explanation: Enzyme activity is measured by how quickly substrate is converted into product, which is expressed as the rate of reaction. Students may choose c because pH affects enzyme activity, but pH is a factor being tested, not the direct measure of activity.

1526. An enzyme which converts a dipeptide into separate amino acids is an example of__________?

• A. Decarboxylase
• B. Hydrolase
• C. Oxidoreductase
• D. Transferase

Explanation: Hydrolases break chemical bonds by adding water, so a dipeptidase hydrolyses the peptide bond and releases two amino acids. The likely alternative is decarboxylase, but decarboxylases remove carboxyl groups and do not split peptide bonds.

1527. Optimal temperature of enzymes present in human body is_____________?

• A. 27?C
• B. 37?C
• C. 47?C
• D. 30?C

Explanation: Most human enzymes have an optimum temperature close to normal body temperature, about 37 °C, where enzyme-substrate collisions and molecular stability are balanced. Above this temperature, many enzymes lose their three-dimensional shape and become denatured. Students may choose 47 °C because a higher temperature can increase reaction rate briefly, but it soon damages enzyme structure.

1528. Which statement about enzyme is incorrect_________________?

• A. Some of them consist solely of protein with no non protein part.
• B. They catalyze a chemical reaction without being utilized.
• C. All enzymes are fibrous Proteins.
• D. They without their cofactor are called apoenzyme.

Explanation: Enzymes are generally globular proteins, not fibrous proteins, because their folded three-dimensional structure creates the active site. A student may choose d because apoenzymes lack their cofactors, but that statement is correct; the apoenzyme becomes active when combined with its cofactor.

1529. A cofactor made of inorganic ion which is detachable is called__________________?

• A. Prosthetic group
• B. Coenzyme
• C. Activator
• D. Cofactor

Explanation: A detachable inorganic ion that assists enzyme activity is called an activator, such as Mg2+ or Zn2+. A student may choose cofactor because an activator is a type of cofactor, but “cofactor” is the broader term and the question asks for the specific category of detachable inorganic ions.

1530. Biological molecules (proteins) which catalyze a biochemical reaction and remain unchanged after completion of reaction are called_____________________?

• A. Cofactor
• B. Coenzymes
• C. Activator
• D. Enzymes

Explanation: Enzymes are biological catalysts, usually proteins, that speed biochemical reactions by lowering activation energy and remain chemically unchanged after the reaction. The likely alternative is coenzyme, but a coenzyme is a non-protein helper molecule, not the complete protein catalyst itself.