explain two reasons why cells must divide when they reach a certain size?

Answer 1

The basic reason for a cell to divide is to maintain favourable surface area to volume ratio. A cell membrane of specific area can serve the contents of a particular volume only. Increase in the volume increases the requirements of the cell and this increases the need for greater membrane area.Now,the Surface area of a sphere increase as the square of the radius and the volume of a sphere increases as the cube of the radius or to say, in simpler words,the volume of the cell increase more rapidly then the area of its membrane.

Hence, as a cell grows,it's membrane in due course of time becomes insufficient to move the required amount of substances in and out. The cell by dividing has a more favourable surface area to volume ratio. Thus, the cell divide so as to maintain it's size such that all it's requirements of nutrition,respiration and excretion are met.

In germ cells, they need to divide so that the sperm and the ovum have haploid set of genes.

Answer 2

Well, first of all, all cells are pretty darn small. They need to be small so the nucleus (containing DNA) can control everything that is going on inside the cell. Furthermore, as an object increases in size, its volume starts to outgrow its surface area. Since the surface area of a cell is its plasma membrane (which controls what enters and exits the cell), we can't have the volume outgrowing the surface area. Finally, materials are constantly having to enter and exit the cell for it to survive. If the cell is too large, it will take longer for materials to enter and exit, which would not be good. So....cells must divide when they reach a certain size and hormonal signals trigger cell division.

Answer 3

they get either too big so they have to separate, or it is just the size of growth in which it reproduces, maybe it has an offspring reproduction.