Chapter Exam

Chapter 3: Control of Microorganisms by Chemical Methods — Online MCQ Test

Q: Which of the following is an antiseptic?

Answer: B. Iodine — Iodine is commonly used on living tissues as an antiseptic. It helps prevent microbial growth on skin and wounds.

Q: A hospital wants to sterilize heat-sensitive plastic syringes. Which chemical sterilant is most appropriate?

Answer: A. Glutaraldehyde — Glutaraldehyde is a high-level chemical sterilant/disinfectant used for heat-sensitive medical equipment. It can destroy a wide range of microorganisms, including spores with sufficient exposure.

Q: Which sequence correctly shows increasing level of microbial control?

Answer: A. Antiseptic < disinfectant < sterilant — Antiseptics are generally milder and used on living tissues, disinfectants are stronger for surfaces, and sterilants provide the highest level of microbial killing. Hence the order increases from antiseptic to sterilant.

MICROBIOLOGY · CLASS 12th · Tamil Nadu State Board

Practice Chapter 3: Control of Microorganisms by Chemical Methods with a free chapter-wise online MCQ test for Tamil Nadu State Board CLASS 12th MICROBIOLOGY. This chapter covers: This chapter investigates chemical agents used to inhibit or kill pathogenic and spoilage microorganisms. It details the classification and mechanisms of disinfectants antiseptics.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 3: Control of Microorganisms by Chemical Methods — Important Questions & Answers (FAQ)

Frequently asked questions from Tamil Nadu State Board CLASS 12th MICROBIOLOGY — Chapter 3: Control of Microorganisms by Chemical Methods, with answers and explanations. These are sample questions; the exam has its own separate question set.

What is the main purpose of using disinfectants?

A. To destroy all forms of microbial life including spores
B. To reduce or destroy microorganisms on inanimate objects ✓
C. To promote growth of beneficial microbes
D. To stain bacterial cells for microscopy

Answer: B. To reduce or destroy microorganisms on inanimate objects
Disinfectants are chemical agents used on non-living surfaces to reduce or destroy microorganisms. They are not necessarily effective against all spores.

Which of the following is an antiseptic?

A. Phenol
B. Iodine ✓
C. Bleach
D. Formaldehyde

Answer: B. Iodine
Iodine is commonly used on living tissues as an antiseptic. It helps prevent microbial growth on skin and wounds.

70% alcohol is more effective than absolute alcohol because it:

A. evaporates faster and reaches deeper tissues
B. acts only on spores
C. denatures proteins better in the presence of water ✓
D. is less toxic to microorganisms

Answer: C. denatures proteins better in the presence of water
Water helps alcohol denature proteins more effectively and allows better penetration. Absolute alcohol acts less efficiently than 70% alcohol.

A hospital wants to sterilize heat-sensitive plastic syringes. Which chemical sterilant is most appropriate?

A. Glutaraldehyde ✓
B. Soap solution
C. Table salt
D. Sucrose

Answer: A. Glutaraldehyde
Glutaraldehyde is a high-level chemical sterilant/disinfectant used for heat-sensitive medical equipment. It can destroy a wide range of microorganisms, including spores with sufficient exposure.

Which sequence correctly shows increasing level of microbial control?

A. Antiseptic < disinfectant < sterilant ✓
B. Sterilant < antiseptic < disinfectant
C. Disinfectant < antiseptic < sterilant
D. Antiseptic < sterilant < disinfectant

Answer: A. Antiseptic < disinfectant < sterilant
Antiseptics are generally milder and used on living tissues, disinfectants are stronger for surfaces, and sterilants provide the highest level of microbial killing. Hence the order increases from antiseptic to sterilant.

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Chapter 4: Microbial Metabolism