as in monohybrid crosses, you can’t tell by looking at the dominant trait whether it is homozygous...
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Dihybrid test cross or back cross
As in monohybrid crosses, you can’t tell by looking at the dominant trait whether it is homozygous or heterozygous.
Dihybrid test cross/back cross
As in monohybrid crosses, you can’t tell by looking at the dominant trait whether it is homozygous or heterozygous.
So in order to find out what the genotype is – do a test cross with an organism that has both recessive characteristics.
Dihybrid test cross/back cross
As in monohybrid crosses, you can’t tell by looking at the dominant trait whether it is homozygous or heterozygous.
So in order to find out what the genotype is – do a test cross with an organism that has both recessive characteristics.
- If the parent is heterozygous you get a ratio of 1:1:1:1
Dihybrid test cross/back cross
As in monohybrid crosses, you can’t tell by looking at the dominant trait whether it is homozygous or heterozygous.
So in order to find out what the genotype is – do a test cross with an organism that has both recessive characteristics.
- If the parent is heterozygous you get a ratio of 1:1:1:1
- If it is homozygous, all the offspring will show the dominant phenotype for both characteristics.
Dihybrid test cross/back cross
Genotype: AaBb x aabbGametes:
Example
Genotype: AaBb x aabbGametes: AB Ab aB ab ab
Example
Genotype: AaBb x aabbGametes: AB Ab aB ab ab
Punnett Square:
Example
Genotype: AaBb x aabbGametes: AB Ab aB ab ab
Punnett Square:
Example
ab
AB AaBb
Ab Aabb
aB aaBb
ab aabb
Now, you have an organism that is homozygous dominant for one trait, but heterozygous for the other – the test cross/back cross still works.
Example
Now, you have an organism that is homozygous dominant for one trait, but heterozygous for the other – the test cross/back cross still works.
In the cross:- For the homozygous dominant
characteristic, no recessive trait will show up in the offspring
Example
Now, you have an organism that is homozygous dominant for one trait, but heterozygous for the other – the test cross/back cross still works.
In the cross:- For the homozygous dominant
characteristic, no recessive trait will show up in the offspring
- For the heterozygous characteristic the recessive trait will show up
Example
Genotype: AABb x aabbGametes:
Example
Genotype: AABb x aabbGametes: AB AB Ab Ab ab ab ab ab
Example
Genotype: AABb x aabbGametes: AB AB Ab Ab ab ab ab ab
Punnett Sq:
Example
Genotype: AABb x aabbGametes: AB AB Ab Ab ab ab ab ab
Punnett Sq:
Example
ab
AB AaBb
Ab Aabb
Genotype: AABb x aabbGametes: AB AB Ab Ab ab ab ab ab
Punnett Sq:
ALL show the dominant trait for A and HALF show the recessive trait for B. From this, you can deduce the genotype as AA for trait A and Bb for trait B
Example
ab
AB AaBb
Ab Aabb