Ek biomolecules Genetics

[5words]

Here's the question:



The answer Choice is actually A , here is their explanation: (second entry below)



However, i check everywhere online and the consensus is the Genotypic ratio ought to be 1:2:1:2:4:2:1:2. So , i am a bit confused, like who is right.. Also check on Khan Academy. Here is the writer comment:



So is it safe to go with the EK reasoning or are they wrong on this one?

@aldol16 @neurodoc @Next Step Tutor @Pono_0001 @MedVIP

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[Pono_0001]

ya it's genotypical ratio not phenotypical, so it's definitely not 9331. even for phenotypic ratio, ya it'd be 12:3:1 since it's dominant epistasis. In fact even the explanation says B is the ratio for dominant epistasis. It's also a very badly written question. the 9331 ratio is only observed if F1 is heterozyous for both traits. I haven't done EK yet but kinda alarming to see questions like these

 

[5words]

ya it's genotypical ratio not phenotypical, so it's definitely not 9331. even for phenotypic ratio, ya it'd be 12:3:1 since it's dominant epistasis. In fact even the explanation says B is the ratio for dominant epistasis. It's also a very badly written question. the 9331 ratio is only observed if F1 is heterozyous for both traits. I haven't done EK yet but kinda alarming to see questions like these

Thought so, was alarmed .. almost changed my notes... because theit explanation is Def wrong but reading this article last night , https://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel6.htm (second table) it seems as if the genotypic ratio or epiptatic gene is 9:3:3:1 ...

So my question is the answer choice correct but the explanation wrong? Because the article clearly state that the epiptatic genotypic ratio ought to be 9:3:3:1 .. However these are not the same as the 1:2:1:4... observed in a normal do hybrid cross..

 

[Pono_0001]

The answer choice would still be wrong if they were asking for the phenotypic ratio of a heterozygous dihybrid cross for dominant epistasis. 9:3:3:1 is the ratio is there's no epistasis or complementary gene interaction

 

[5words]

The answer choice would still be wrong if they were asking for the phenotypic ratio of a heterozygous dihybrid cross for dominant epistasis. 9:3:3:1 is the ratio is there's no epistasis or complementary gene interaction

ok, look as if you didn't check, but here what i am saying:

Let's supposed the question asking us for epiptatic genotype ratio:
This website says this :

image uploader

I have highlighted the genotypic ratio and phenotypic ratio, because in epiptasis the Dominant allele cover the recessive expression , it follows that the genotypic ratio is indeed 9:3:3:1 for dihybrid epiptatic crosses. Hence, my next question, is the Question right despite the faulty answer choice? So, should the answer choice be updated because Normal dihybrid cross dont have a 9:3:3:1 genotypes, they have a 1:2:1:4, etc...

td'lr: The Answer choice posit that EVERY independent assorting genes should have a 9:3:3:1 genotypic ratio , granted that they are dihybrids, which isnt true for normal genes. So is that wrong?? because it based on the paper posted, epiptatic genes do have a 9:3:3:1 genotypic ratio! Anyone can chime in, btw.. i am making sure, i am not missing anything out.

 

[Pono_0001]

9331 is not a genotypic ratio though. AABB AABb AaBB They'd all fall under A-B-, so that's 3 genotype but under the same phenotype. The table isn't grouping it by genotypical ratio. it's just helping you see to figure out the 15:1 ratio using the 9:3:3:1 phenotypic ratio.

 

[5words]

9331 is not a genotypic ratio though. AABB AABb AaBB They'd all fall under A-B-, so that's 3 genotype but under the same phenotype. The table isn't grouping it by genotypical ratio. it's just helping you see to figure out the 15:1 ratio using the 9:3:3:1 phenotypic ratio.

Make sense.. using their own reasoning the genotype ratio SHOULDN'T change so long as both genes are as sorting independently.. so it ought to stay 1:2:1:2:4:2:1:2:1 but the phenotypic ratio would (9:3:3:1 in normal vs 15:1 or any other alteration in epiptasis) lol thanks pal.. it's crystal clear now.