Question

Lignin is a complex polymer which can be stained pink in the tissue using the following chemicals?

• A. Chloral Hydrate and Phloroglucinol
• B. Chlor-Zinc-Iodine
• C. Phloroglucinol and hydrochloric acid
• D. Chloral Hydrate, Zinc andAmmonia

Answer 1

The Correct Option is C

Lignin is an integral part of the plant cell walls, primarily composed of complex polymers. It provides rigidity and does not easily decompose. When testing for the presence of lignin in plant tissues, certain chemical reactions are used that produce specific color changes as an indication of its presence.

The question asks for the chemicals used to stain lignin pink. Here's the breakdown of the options:

1. Chloral Hydrate and Phloroglucinol: Chloral hydrate is typically used as a clearing agent in microscopic preparations but does not interact with lignin to produce a pink color. Phloroglucinol is one of the reagents used in staining lignin; however, it needs another reagent to produce the characteristic pink color.
2. Chlor-Zinc-Iodine: This reagent is not used for staining lignin. It is typically used for the identification of starch.
3. Phloroglucinol and hydrochloric acid: This combination is the correct staining method for lignin. Upon treatment with hydrochloric acid and phloroglucinol, lignin turns a pink to red color. This pink coloration results from the reaction between lignin and the reagents.
4. Chloral Hydrate, Zinc and Ammonia: Again, this combination is not involved in the staining of lignin. Chloral hydrate serves as a clearing agent and does not result in a pink coloration with lignin.

Conclusion: The correct choice is Phloroglucinol and hydrochloric acid as they specifically react with lignin to give it a pink coloration, indicating its presence in the tissue.