Answer: mitosis.
During DNA replication a pair of chromosomes of from one cell genders two duplicated chromosomes (so the number of chromosomes is duplicated), then in the mitosis process the cell split into two identical cells each with half of the duplicated chromosomes, so at the end one cell with two chromosomes form two cells each with two chromosomes. So, the new generation of cells has the same number of chromosomes.
The answer is; When the planet is at A it is moving faster than at B.
This is because when the planet is closer to the sun at point A, it is experiencing a stronger gravitation, by the sun, pull than at point B. Therefore, its acceleration due to gravity at point A is higher than at point B.