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In some bees, thin stripes (S) are dominant over thick stripes (s) and black eyes (B) are dominant over gray eyes (b). Complete a dihybrid cross for parents with the genotypes: SsBB × ssBb and answer the following in complete sentences.



Describe how you would set up a Punnett square for this cross.

List the likelihood of each possible offspring genotype.

List the likelihood of each possible offspring phenotype.

Verified Answer :

The answer to your question is
SsBB can produce two kinds of gametes SB and sb
ssBb can produce two kinds of gametes sB and sb

You would do a 2X2 Punnett square

You will find 1/4 SsBB, 1/4 SsBb, 1/4 ssBb and 1/4 ssbb

In terms of phenotypes, 1/2 will be thin, black, 1/4 thick black and 1/4 thick gray.

Answer:

a) Genotype Ratio -

SsBB: ssBB: SsBb: ssBb

4:4:4:4

1:1:1:1

b) Phenotype Ratio

Thin striped and Black eye : Thick striped and Black eye

8:8

1:1

Explanation:

It is given that -

a) Thin stripes (S) are dominant over thick stripes (s)

b) Black eyes (B) are dominant over gray eyes (b)

The punnet table representing  the cross between SsBB × ssBb is as follows -

 SB         SB         sB         sB

sB SsBB SsBB ssBB ssBB

sb SsBb SsBb ssBb ssBb

sB SsBB SsBB ssBB ssBB

sb SsBb SsBb ssBb ssBb

Genotype Ratio -

SsBB: ssBB: SsBb: ssBb

4:4:4:4

1:1:1:1

Phenotypic Ration -

SsBB - Thin striped and Black eye

ssBB- Thick striped and Black eye

SsBb-  Thin striped and Black eye

ssBb- Thick striped and Black eye

Thin striped and Black eye : Thick striped and Black eye

8:8

1:1

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