TN State Board 12th Microbiology Question Paper 2026

CLSM (Confocal Laser Scanning Microscope) and LCSM refer to optical imaging techniques used to view specimens with light. TEM (Transmission Electron Microscope) is not optical; it is an electron microscopy technique. Hence, both (a) and (b) are correct.

In TEM, the lenses used are electromagnetic lenses. These lenses focus and direct the electron beam. Glass lenses cannot be used because TEM works with electrons, not visible light. Therefore, the correct answer is electromagnetic lens.

An antiseptic is used on living tissues, such as animal or human tissue, to prevent infection by killing or inhibiting the growth of pathogens. Disinfectants are generally used on non-living surfaces, bacteriostatic agents only inhibit growth, and sanitizers reduce microbial load but are not specifically defined for living tissue. Hence, antiseptic is correct.

An apoenzyme is the protein part of an enzyme, and when it combines with its cofactor, it forms the active holoenzyme. Therefore, Apoenzyme + Cofactor = Holoenzyme. The other options are incorrect because a coenzyme is only one type of cofactor, not the result of combining apoenzyme and holoenzyme.

The minimum water activity ($a_w$) generally required for the growth of microorganisms in foods is around 0.86. Most bacteria need higher $a_w$ values, while some yeasts and molds can grow at slightly lower values. Therefore, 0.86 is the correct answer.