Answer:
Because cells that result from mitosis are diploid i.e. contain two sets of chromosomes.
Step-by-step explanation:
Mitosis is a type of cell division that produces daughter cells that are genetically identical to the parent cell. The chromosomal number of cells formed from mitosis remains the same as the parent cell. This means that if a parent is diploid (2n), the daughter cells from mitotic division will be diploid (2n).
However, for fertilization during sexual reproduction to occur, two haploid or half of the chromosome number of the parental organism must unite to form a whole diploid organism. In other words, two haploid cells (n + n) must come together in fertilization to give a diploid cell (2n). Hence, combining cells that result from mitosis would not work for fertilization because cells that result from mitosis are already diploid i.e. contain two sets of chromosomes.