Cells of different species, when observed in nutrient solutions, are seen to divide varying numbers of times, with cells of the most long-lived species dividing more times than the cells of short-lived species. The total number of divisions for any given species is sometimes referred to as ,

Explanation:

The total number of divisions for any given species is sometimes referred to as The Hayflick limit or The Hayflick  phenomenon.  

The mechanisms behind cellular aging was explained by the Hayflick limit or Hayflick  phenomenon. According  to  Hayflick, a normal human cell can divide  approx forty to sixty times, then it cannot divide anymore.

After  forty to sixty divisions cell will break down by programmed cell death or apoptosis.

i think its the first one

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.