In a plant, two autosomal loci Aand B are linked at 20 m.u. What proportion of t
ID: 26212 • Letter: I
Question
In a plant, two autosomal loci Aand B are linked at 20 m.u. What proportion of the progeny with a phenotype AB will be obtained if a double heterozygous plant (aB/Ab) is testcrossed:a) 5%
b) 10%
c) 20%
d) 50%
e) 3/16
Why is the answer B) 10%???
Can you please elaborate? I thought the cross would be aB/Ab x ab/ab
If that were the case wouldn't the offspring be :AaBb, Aabb, aaBb, aabb?
With a 20% recombination rate, wouldn't AaBb and aabb (parental) have an 80% probability? With that, I got 40%/2 = 20% for an AB phenotype. Please help.
In other words...why doesn't using a branch diagram work for linked genes problems?
Explanation / Answer
In a plant, two autosomal loci Aand B are linked at 20 m.u. What proportion of the progeny with a phenotype AB will be obtained if a double heterozygous plant (aB/Ab) is testcrossed:
a) 5%
b) 10%
c) 20%
d) 50%
e) 3/16
Why is the answer B) 10%???
Test cross aa bb X aBAb
Gamtes
ab
aB
ab aB
ab
ab ab
BA
ab BA
Bb
ab Bb
est cross ration –s 1:1:1:!
Gamtes
ab
aB
ab aB
ab
ab ab
BA
ab BA
Bb
ab Bb
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