Question

does mitosis or meiosis begin with haploid cells?

Answer 1

Mitosis

Answer 2

Meiosis is reduction division i.e it halves the chromosome number in a cell or makes a diploid cell haploid. Mitosis is equational division i.e it doesn't change the ploidy (chromosome number) of a cell.

So Mitosis can start with both haploid and diploid cell but Meiosis always starts with a diploid cell and ends into haploid cells.

Answer 3

Note that, in humans and most other animals, haploid cells don't undergo mitosis.