Question

Given below are two statements.

Statement I: Dry heat destroys microbes primarily by oxidation process.

Statement II: Dry heat is used to sterilize oils, powders and sealed containers.

In light of the above statements, choose the correct answer from the options given below.

• A. Both Statement I and Statement II are true.
• B. Both Statement I and Statement II are false.
• C. Statement I is true but Statement II is false.
• D. Statement I is false but Statement II is true.

Hint:

Remember the distinction: Dry heat = Oxidation (Hot air oven: 160--170$^\circ$C for about 2 hours), whereas Moist heat = Protein coagulation (Autoclave: 121$^\circ$C at 15 psi for 15 minutes).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Dry heat sterilization is a physical method of sterilization that destroys microorganisms by oxidative damage and protein denaturation.
It is particularly suitable for materials that cannot be sterilized by moist heat, such as oils, powders, and glassware.
Detailed Explanation:
Statement I:
Dry heat acts mainly through oxidation of cellular constituents and dehydration of microbial cells.
Exposure to high temperatures causes irreversible damage to proteins, nucleic acids, and cell membranes, resulting in microbial death.
Therefore, Statement I is true.
Statement II:
Hot air oven sterilization is commonly used for substances that are impermeable to steam or damaged by moisture.
Examples include oils, fats, powders, glassware, and sealed glass containers.
Hence, Statement II is true.

Step 2: Final Answer:
Both Statement I and Statement II are true.
\[ \boxed{(A) Both Statement I and Statement II are true. \]