# Gcse biology question(urgent!)

#1
Heres the question:
The screening technique is carried out on a cell from an embryo just after 3 cell divisions(mitosis) of the fertilised egg.How many cells will there be in an embryo after 3 cell divisions of the fertilised egg?

I know the answer is 8 but don't know how to work it out.
0
#2
Anyone?
0
6 years ago
#3
Each mitotic division gives rise to two daughter cells (so the number of cells doubles with each division), so...

1 division = 2 cells
2 divisions = 4 cells
3 divisions = 8 cells

That's all there is to it as far as I can see!
1
6 years ago
#4
Anyone?
During Mitosis, one cell divides into 2 identical daughter cells.

1 cell divides into 2. Then each of those 2 cells divides into 2. Then each of those 4 cells divides into 2.

Let's say 'O' represents a cell...
Division 1: O --> O + O
Division 2: O + O --> O + O + O + O
Division 3: O + O + O + O --> O + O + O + O + O + O + O + O

You're left with 8 cells, make sense?
1
#5
(Original post by Neuth)
During Mitosis, one cell divides into 2 identical daughter cells.

1 cell divides into 2. Then each of those 2 cells divides into 2. Then each of those 4 cells divides into 2.

Let's say 'O' represents a cell...
Division 1: O --> O + O
Division 2: O + O --> O + O + O + O
Division 3: O + O + O + O --> O + O + O + O + O + O + O + O

You're left with 8 cells, make sense?
Yeah, I was a bit stupid for not being able to do this by myself.
0
6 years ago
#6
2^3. Every iteration increases the exponent by 1.
0
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