In a haploid plant,which type of cell division is useful for gamete formation?

Mitosis occurs in

Which of the following maintains the chromosome number in daughter cells?

The process of mitosis can be studied in

Assertion : Old age is not an illness. It is a continuation of life with decreasing capacity for adaptation.
Reason : Cessation of mitosis is a normal genetically programmed event.

Which is the best material for studying mitosis in the laboratory?