If you wanted to increase an enzymes activity you would need a/an

in normal case, after mitosis, a plant cell will produce 2 daughter cells with 2n chromosomes.

but in this case,

a chemical is used which inhibits cell plate formation. if cell plate is not formed then,

after mitosis, miracle berry plant cell will end up with having 1 daughter cell with 2n no. of chromosomes (2n =15). (no cell plate formation = 1 daughter cell)