Question

Pollen grains of a plant $(2n=28)$ are cultured to get callus by tissue culture. What would be the number of chromosomes in the cells of callus?

• A. $14$
• B. $21$
• C. $56$
• D. $28$

Answer 1

The correct option is A $14$

Callus
Callus is a group of undifferentiated cells that is formed from the explant in a sterilised nutrient medium during tissue culture.

Ploidy of the pollen grain
The pollen grains are haploid in nature, which implies that the number of chromosomes it contains will be half of that in the parent plant cell. Therefore it contains $14$ chromosomes, as the diploid number of the parent plant cell is $28$.

Ploidy of the callus
Callus is formed by the repeated mitotic divisions of the explant, which in this case is the pollen grain. Therefore, the cells of the callus will also contain $14$ chromosomes.