Question

The stock sperm solution you will use for fertilization is "1 drop in 50ml ASW"

Undiluted sea urchin sperm fluid contains about 2 x 10^10 sperm/ml (assume one drop is 0.5 ml)

What is the dilution factor, and what is the final concentration you are using?

Answer 1

From stock sperm solution if we take 1 drop in 50ml ASW

when 1 drop is 0.5ml, thus if we take 0.5ml in 50 ml ASW

then the dilution is 50/ 0.5 = 1:100, thus the dilution factor is 100

when we take 0.5 ml, that means we are taking -

1ml contains 2 x 10^10 sperm

thus 0.5 ml contains- 2 x 10^10 X 0.5 /1 = 1 x 10^10 sperm

as this amount of sperm is present now in 50 ml

then in 50 ml contains-1 x 10^10 sperm

           1 ml contains- 1 x 10^10 sperm X1/ 50 =0.02 x 10^10 sperm/ml