Question

Which of the following can not be used as a fixative?

(a) formaldehyde

(b) acetic acid

(c) alcohol

(d) vitamin B12

The question was posed to me by my school principal while I was bunking the class.

My doubt is from Techniques in division Techniques in Cell Biology of Cell Biology

Answer 1

A fixative is a substance used to preserve biological specimens by stabilizing their structure, preventing degradation, and preparing them for microscopic examination. Let’s analyze the options in terms of their role as fixatives:

• (a) Formaldehyde: Correct. Formaldehyde is a commonly used fixative in cell biology as it cross-links proteins, helping to preserve cell structure.

• (b) Acetic acid: Acetic acid can also be used as a fixative, particularly when combined with other chemicals (e.g., in Carnoy's fixative), as it helps preserve cell membranes and nucleic acids.

• (c) Alcohol: Alcohol (usually ethanol or methanol) is frequently used as a fixative. It works by dehydrating cells and precipitating proteins, which helps in preservation.

• (d) Vitamin B12: Vitamin B12 is not used as a fixative. It is a vitamin and is not suitable for preserving biological specimens for microscopy.

Correct Answer: (d) Vitamin B12