Question

Callus is defined as:

• A. Mass of schlerenchymatous tissue with meristematic loci
• B. Mass of parenchymatous tissue with meristematic loci
• C. Mass of schlerenchymatous tissue with nonmeristematic loci
• D. Mass of parenchymatous tissue with nonmeristematic loci

Hint:

Think of Callus as "Parenchyma + Division." It is the "blank slate" of plant tissue culture from which new plants are regenerated.

Answer 1

The Correct Option is B

Concept: In plant tissue culture, a callus is a disorganized mass of unspecialized cells. It is primarily composed of thin-walled, living cells that have the potential to differentiate into various plant organs under specific hormonal conditions.

Step 1: Understanding Cell Type and Nature.
Callus consists of parenchymatous cells, which are characterized by being relatively undifferentiated and having thin primary cell walls. Unlike sclerenchyma (which are dead, thick-walled supporting cells), parenchyma cells remain metabolically active and are capable of cell division.

Step 2: Identifying Meristematic Activity.
A callus is not just a random heap of cells; it contains meristematic loci or "meristemoids." These are small groups of actively dividing cells within the callus mass that serve as the starting points for organogenesis (the formation of roots or shoots).

Step 3: Conclusion.
Therefore, a callus is accurately defined as a mass of parenchymatous tissue containing meristematic loci, making option (2) the correct choice.