Respuesta :
Answer:
Fraction of the offspring with red, axial flowers is [tex]\frac{9}{16}[/tex]
Explanation:
Let the allele for red flower be represented by "R" and the allele for white flower be represented by "r" and R is a dominant trait over r.
Let the allele for axial flower be represented by "A" and the allele for terminal flower be represented by "a" and A is a dominant trait over a
F1 cross
RRAA * rr aa
RrAa
F2 Cross
RrAa * RrAa
RrAa
RA Ra rA ra
RA RRAA RRAa RrAA RrAa
Ra RRAa RRaa RrAa Rraa
rA RrAA RrAa rrAA rrAa
ra RrAa Rraa rrAa rraa
Possible genotypes
RRAA - 1
RRAa- 2
RrAA- 2
RrAa- 4
RRaa- 1
Rraa- 2
rrAA- 1
rrAa – 2
rraa- 1
Possible Phenotypes –
Red & Axial – RRAA, RRAa, RrAA, RrAa
Red & Twisted – Rraa, Rraa
White and Axial – rrAA, rrAa
White and Twisted - rraa
Fraction of the offspring with red, axial flowers is [tex]\frac{9}{16}[/tex]
Answer:
9/16.
Explanation:
Let us suppose R gene controls flower color while A gene controls flower position.
Given:
One parent has = red, axial flowers with genotype RRAA
Other parent has = white, terminal flowers with genotype rraa
F1 individuals = all are red, axial flowers.
Since all F1 progeny are red, axial flowers then it means that red is dominant over white color and axial position is dominant over terminal position.
The parent which has 'RRAA genotype' will produce 4 identical gametes with 'RA allelic' combination while the parent which has 'rraa genotype' will produce 4 identical gametes with 'ra allelic' combination.
When both these gametes will fuse, they may produce 16 progeny with same 'genotype RrAa'. The cross is depicted as under:
Parental genotype: RRAA x rraa
I I
Gametes: RA ra
F1 genotype: RrAa
When these F1 individuals will be crossed with each other, again 16 progeny will be produced but this time they will have genotypes which are different from each other. The cross is attached:
So it is clear from the punette square diagram of this dihybrid cross that out of the 16 probable progeny, there will be 9 progeny which will have red and axial flowers. So, the fraction of progeny will be 9/16.
These are the 9 genotypes RRAA, RRAa, RrAA, RrAa, RRAa, RrAa, RrAA, RrAa & RrAa of progeny which will have red and axial flowers.
