How to Solve Q6a) and b) in AQA Human Biology 2006 Jan Exam

[jsmith613]

Homework Statement

http://www.xtremepapers.com/AQA/Human%20Biology/2006%20Jan/AQA-BYA5-W-QP-JAN06.pdf

If we look at Q6a) we are asked to find Genotype of parents (Aabb and aaBb) and the gametes formed.

What gametes are formed? and why?
thanks

also, how is part b) calculated?

Homework Equations

The Attempt at a Solution

I have worked out the genotype of
Pea: Aabb
Rose: aaBb

Now I am not sure if the gametes formed are Aa/bb OR Ab/ab
which one is correct and why?

Now, with this how do I do b) [i could not work out it even hypothetically)
thanks

 

[epenguin]

First check or revise you know what a gamete is and what it can contain.

For question (b), which is independent, you need to know two things

i What is the combined (Rose + Single) percent telling you? - check against the given table.

ii What actually is the HW Law, what does it say?

 

[jsmith613]

what does it mean "the genes are inherited indepentandly"

 

[epenguin]

what does it mean "the genes are inherited indepentandly"

To see anything in genetics there have to be differences. So say a parent has a difference in his/her A pair of genes. The parent is Aa. Then the offspring gets A from that parent half the times and gets a half the times. Never mind how the composition shows up as phenotype in the parent or offspring according to the other copy of the gene they have. There are even chances of transmitting one or the other version of the gene.

Now at the other locus, suppose the parent is heterozygous there too, it is Bb. Again it is even chances an offspring gets B or b.

Now suppose a parent is Aa Bb . In most cases if an offspring gets A from it, it has an even chance of getting B or b, and if it gets a it has an even chance of getting B or b. That is the inheritance of A and B are independent.

The extreme opposite is closely linked inheritance. That would be with the above parent, for example whenever the offspring receives A it receives B too and almost never b. That happens when the A gene and the B gene are close together on a chromosome.

The intermediate case when they are neither always together nor independent which happens when A and B are on the same chromosome but get separated by crossovers.

I hope this eases or confirms explanations that must be in your textbook - we here cannot substitute for those.

 

[jsmith613]

thanks for that!

 

[jsmith613]

i also understand the next bit
so question sorted! yey!

 

[epenguin]

i also understand the next bit
so question sorted! yey!

What was the answer?