Find probability (Genetics)

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. :s-smilie:

Thanks for your help :smile:

http://img842.imageshack.us/i/snipy.png/

Reply 1

hissyfit

15

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. :s-smilie:

Thanks for your help :smile:

http://img842.imageshack.us/i/snipy.png/

I m not sure on the answer,but is this an IB.

Reply 2

ibysaiyan

OP

16

Original post by hissyfit

I m not sure on the answer,but is this an IB.

Nope.OCR

Reply 3

Gowrav

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. :s-smilie:

Thanks for your help :smile:

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?

Reply 4

ibysaiyan

OP

16

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%

Reply 5

Melanie-v

10

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.

Reply 6

ibysaiyan

OP

16

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 ?

(edited 13 years ago)

Reply 7

Melanie-v

10

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 :tongue:

Reply 8

ibysaiyan

OP

16

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 :tongue:

Tyvm. Now I get the picture.No doubt about it :P

Find probability (Genetics)

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