# Find probability (Genetics) Watch

1. Hello,
I don't find myself at ease with this particular questions last bit. I have done all the previous parts but what I don't get is why have they highlighted "non-identical twins" ? from the previous question I found the ratio of Blood Group A to be 1:3 and I am aware that identical twins carry same genotype.
http://img842.imageshack.us/i/snipy.png/
2. (Original post by ibysaiyan)
Hello,
I don't find myself at ease with this particular questions last bit. I have done all the previous parts but what I don't get is why have they highlighted "non-identical twins" ? from the previous question I found the ratio of Blood Group A to be 1:3 and I am aware that identical twins carry same genotype.
http://img842.imageshack.us/i/snipy.png/
I m not sure on the answer,but is this an IB.
3. (Original post by hissyfit)
I m not sure on the answer,but is this an IB.
Nope.OCR
4. (Original post by ibysaiyan)
Hello,
I don't find myself at ease with this particular questions last bit. I have done all the previous parts but what I don't get is why have they highlighted "non-identical twins" ? from the previous question I found the ratio of Blood Group A to be 1:3 and I am aware that identical twins carry same genotype.
http://img842.imageshack.us/i/snipy.png/
Thats a easy question. Provide me with the WHOLE question and not just part of it and I will have a go. Besides it looks like its from AQA paper..so why not look up the answer/method?
5. (Original post by Gowrav)
Thats a easy question. Provide me with the WHOLE question and not just part of it and I will have a go. Besides it looks like its from AQA paper..so why not look up the answer/method?
It's from OCR and the answer for it is: 1/4 X 1/4 = 1/16. I just dont get it, why do they need to be multiplied to give 6.25%
6. The mother must be AO, and the father must be BO.
Draw the individual "gametes"
ie. A O B O
Then check the possible combinations:
AB AO BO OO

so it's a 1/4 chance of blood group A for one child. For two children it is 1/4 * 1/4 =1/16,

so a 1/16 chance.
7. (Original post by Melanie-v)
The mother must be AO, and the father must be BO.
Draw the individual "gametes"
ie. A O B O
Then check the possible combinations:
AB AO BO OO

so it's a 1/4 chance of blood group A for one child. For two children it is 1/4 * 1/4 =1/16,

so a 1/16 chance.
Ah I see now.. they were asking for two children...Thanks
Edit: Oh so if they were identical twins then their probability be 2/4 ?
8. (Original post by ibysaiyan)
Ah I see now.. they were asking for two children...Thanks
Edit: Oh so if they were identical twins then their probability be 2/4 ?
Nope, still 1/4. You imagine the identical twins as 1 child in terms of genetics, as everything is decided, genetically speaking (so the probability of blood groups depends on this), and then the egg splits.

1)the gametes fuse
2)the egg splits.

1 is where you get the probability from.

EDIT: twinhood is confusing
9. (Original post by Melanie-v)
Nope, still 1/4. You imagine the identical twins as 1 child in terms of genetics, as everything is decided, genetically speaking (so the probability of blood groups depends on this), and then the egg splits.

1)the gametes fuse
2)the egg splits.

1 is where you get the probability from.

EDIT: twinhood is confusing
Tyvm. Now I get the picture.No doubt about it :P

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Updated: December 23, 2010
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