A level Bio helpWatch

#1
Attachment 624602How do I work out the phenotype ratio?
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#2
Any ideas
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2 years ago
#3
it says attachment nt available
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#4
(Original post by sayema1)
it says attachment nt available
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#5
Is it working now
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2 years ago
#6
Since all the columns are the same (because the father is homozygous in both traits), you can just look at 1 column and you will get the same answer.

Look at the phenotype produced by each genotype in the boxes. Assuming there is no codominance or epistasis etc, you know that any genotype like AA or Aa would show the dominant trait, and the genotype aa would show the recessive trait. I would label each box with the phenotype it produces first of all. For example, the top left box would have the dominant trait for both A and B, so that is its phenotype. So would the second box down.

After that, count how many boxes contain each phenotype has, and work out the ratio between the different numbers.
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#7
(Original post by lizardlizard)
Since all the columns are the same (because the father is homozygous in both traits), you can just look at 1 column and you will get the same answer.

Look at the phenotype produced by each genotype in the boxes. Assuming there is no codominance or epistasis etc, you know that any genotype like AA or Aa would show the dominant trait, and the genotype aa would show the recessive trait. I would label each box with the phenotype it produces first of all. For example, the top left box would have the dominant trait for both A and B, so that is its phenotype. So would the second box down.

After that, count how many boxes contain each phenotype has, and work out the ratio between the different numbers.
Would the ratio be 44:4?
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2 years ago
#8
44:4 would simplify to 11:1. That would be correct for the genotype ratio, but you need to consider the phenotype that would happen in each individual as it is asking for phenotype ratio.
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#9
(Original post by lizardlizard)
44:4 would simplify to 11:1. That would be correct for the genotype ratio, but you need to consider the phenotype that would happen in each individual as it is asking for phenotype ratio.
I'm really confused to how you work that out
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2 years ago
#10
Do you know how dominant and recessive genes work? For example, if B was dominant and meant brown eyes, and b was recessive and meant blue eyes, could you work out the colour of eyes for individuals with genotype BB, Bb, or bb?
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#11
(Original post by lizardlizard)
Do you know how dominant and recessive genes work? For example, if B was dominant and meant brown eyes, and b was recessive and meant blue eyes, could you work out the colour of eyes for individuals with genotype BB, Bb, or bb?
I understand that but how like do you work that out
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2 years ago
#12
When they are something like AABb, work it out as:
What would AA mean? (dominant allele A means they have the A characteristic).
What would Bb mean? (they have the dominant allele B, so they have the B characteristic).
The phenotype includes both of those things, so the phenotype would be that they have the A and B characteristics. Then count up how many others have the same. The question you have is a bit of a trick question when it asks for "ratios".
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#13
(Original post by lizardlizard)
When they are something like AABb, work it out as:
What would AA mean? (dominant allele A means they have the A characteristic).
What would Bb mean? (they have the dominant allele B, so they have the B characteristic).
The phenotype includes both of those things, so the phenotype would be that they have the A and B characteristics. Then count up how many others have the same. The question you have is a bit of a trick question when it asks for "ratios".
So wouldn't it be all of them
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2 years ago
#14
Yeah, they all have the same phenotype really.
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#15
Thank you
(Original post by lizardlizard)
Yeah, they all have the same phenotype really.
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