Genetics and the evolution of life (BIOL10005): Exam thread

[Starlight]

Oh yea the phylogeny/phylums are excruciating to learn.

Just remember that we don't need to know the phylogeny diagram though

[claireb]

Oh yea the phylogeny/phylums are excruciating to learn.

Just remember that we don't need to know the phylogeny diagram though

We don't? Is this Rick's diagram or Theresa's?

[Starlight]

Oh yea the phylogeny/phylums are excruciating to learn.

Just remember that we don't need to know the phylogeny diagram though

We don't? Is this Rick's diagram or Theresa's?

pretty sure theresa told us that we wouldn't be tested on that, maybe check out the recordings to be sure

[jinny1]

Is there a quick/simple way of calculating ratios for dihybrid crosses??

Like this question:

In peanuts the phenotype may be either ‘bunch’ or ‘runner’. Two purebreeding bunch plants were crossed and the F1 were all ‘runner’. Allowing the F1 to interbreed produced an F2 with 173 ‘runner’ and 147 ‘bunch’. Propose a genetic hypothesis to explain the inheritance of this trait in peanuts.

All i know how to do is the percentage of each phenotype (173/320 and 147/320) but i don't know how to turn those into ratios :/

I'm guessing some mathematical manipulation is required but i'm terrible at maths.

The percentage is 55% and 45% so i'm guessing it is 9:7 ratio and that both recessive genotypes are epistatic.

[Starlight]

Is there a quick/simple way of calculating ratios for dihybrid crosses??

Like this question:

In peanuts the phenotype may be either ‘bunch’ or ‘runner’. Two purebreeding bunch plants were crossed and the F1 were all ‘runner’. Allowing the F1 to interbreed produced an F2 with 173 ‘runner’ and 147 ‘bunch’. Propose a genetic hypothesis to explain the inheritance of this trait in peanuts.

All i know how to do is the percentage of each phenotype (173/320 and 147/320) but i don't know how to turn those into ratios :/

I'm guessing some mathematical manipulation is required but i'm terrible at maths.

The percentage is 55% and 45% so i'm guessing it is 9:7 ratio and that both recessive genotypes are epistatic.

So (173/320) is 55%

so you're right just solve (x/16) = 0.55

and x= 8.8 so you can round up to 9

[jinny1]

Is there a quick/simple way of calculating ratios for dihybrid crosses??

Like this question:

In peanuts the phenotype may be either ‘bunch’ or ‘runner’. Two purebreeding bunch plants were crossed and the F1 were all ‘runner’. Allowing the F1 to interbreed produced an F2 with 173 ‘runner’ and 147 ‘bunch’. Propose a genetic hypothesis to explain the inheritance of this trait in peanuts.

All i know how to do is the percentage of each phenotype (173/320 and 147/320) but i don't know how to turn those into ratios :/

I'm guessing some mathematical manipulation is required but i'm terrible at maths.

The percentage is 55% and 45% so i'm guessing it is 9:7 ratio and that both recessive genotypes are epistatic.

So (173/320) is 55%

so you're right just solve (x/16) = 0.55

and x= 8.8 so you can round up to 9

Thank you!!

[Starlight]

Has anyone tried the practice exam? It's harder than last sems

[claireb]

Has anyone tried the practice exam? It's harder than last sems

Not yet, two assignments due this week so no exam revision for me right now. Thanks for the heads up though.

[Starlight]

Has anyone tried the practice exam? It's harder than last sems

Not yet, two assignments due this week so no exam revision for me right now. Thanks for the heads up though.

How's the NE assignment? Ah it's so hard balancing exam study and assignments. I think i'm going to try finish my assignment tonight so i'll be free to study the next two days.

[claireb]

Has anyone tried the practice exam? It's harder than last sems

Not yet, two assignments due this week so no exam revision for me right now. Thanks for the heads up though.

How's the NE assignment? Ah it's so hard balancing exam study and assignments. I think i'm going to try finish my assignment tonight so i'll be free to study the next two days.

Harder than the last one. Especially with referring to previous studies when a lot of what we have are other stories that don't relate to the one I'm talking about :/ You?

[Starlight]

Has anyone tried the practice exam? It's harder than last sems

Not yet, two assignments due this week so no exam revision for me right now. Thanks for the heads up though.

How's the NE assignment? Ah it's so hard balancing exam study and assignments. I think i'm going to try finish my assignment tonight so i'll be free to study the next two days.

Harder than the last one. Especially with referring to previous studies when a lot of what we have are other stories that don't relate to the one I'm talking about :/ You?

pretty much in the same situation

[jinny1]

Somebody please help me with this question

[Starlight]

Somebody please help me with this question

Well it rules out C because it's quantitative (i.e. not multifactorial, those are things like spina bifida etc. where it's present or not)

Use Height 188-190 (or 143-145)
I'll just use height 188-190 since it's the base height

so (1/1031)= (1/4)^5 (they are approximately equal)

so there are five polygenes (rules out a)  meaning they have the alleles:

AABBCCDDEE  (rules out b)

To get D:

Find the range= 188 (max height in offspring) - 145 (base height) = 43 cm

10 contributing alleles (AABBCCDDEE) = 43/10 = 4.3cm = close enough to the answer



Also: Try see if you can do the problem at the end of the polygenic inheritance lecture, it's the same method

[jinny1]

Somebody please help me with this question

Well it rules out C because it's quantitative (i.e. not multifactorial, those are things like spina bifida etc. where it's present or not)

Use Height 188-190 (or 143-145)
I'll just use height 188-190 since it's the base height

so (1/1031)= (1/4)^5 (they are approximately equal)

so there are five polygenes (rules out a)  meaning they have the alleles:

AABBCCDDEE  (rules out b)

To get D:

Find the range= 188 (max height in offspring) - 145 (base height) = 43 cm

10 contributing alleles (AABBCCDDEE) = 43/10 = 4.3cm = close enough to the answer



Also: Try see if you can do the problem at the end of the polygenic inheritance lecture, it's the same method

Thanks El but i dont get why you used 1/1031 over any other trait?? That (1/4)^n rule is for finding out how many offpsring are related to the parent. But the question says nothing about that. How do you know it was 1/1031??

[Starlight]

Somebody please help me with this question

Well it rules out C because it's quantitative (i.e. not multifactorial, those are things like spina bifida etc. where it's present or not)

Use Height 188-190 (or 143-145)
I'll just use height 188-190 since it's the base height

so (1/1031)= (1/4)^5 (they are approximately equal)

so there are five polygenes (rules out a)  meaning they have the alleles:

AABBCCDDEE  (rules out b)

To get D:

Find the range= 188 (max height in offspring) - 145 (base height) = 43 cm

10 contributing alleles (AABBCCDDEE) = 43/10 = 4.3cm = close enough to the answer



Also: Try see if you can do the problem at the end of the polygenic inheritance lecture, it's the same method

Thanks El but i dont get why you used 1/1031 over any other trait?? That (1/4)^n rule is for finding out how many offpsring are related to the parent. But the question says nothing about that. How do you know it was 1/1031??

I used the (1/4)^n rule so i could determine the amount of polygenes, given by n. This has to be done to determine the number of contributing alleles (i.e. to rule out b)

I guess when I looked at when it said 1031 offspring, I was like oh hey that's close to 4^5. So i could say (1/1031) = (1/4)^5

Oh and also, none of the other numbers simplify, so they weren't something like (2/32 offspring so I could say 1/16 = (1/4)^2)

Does this sort of makes sense?