ring Enabled: Final Exam

$8$

There are two main types of pencils: mechanical and traditional. mechanical pencils can have single, double, or triple$-$thickness finger pads.

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traditional pencils do not have tinger pads?

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Two traditional pencils only ever have traditional offspring.

Two mechanical pencils of any devel of finger pad thickness can occasionally have traditional pencil offspring. When two pencils with single$-$thickness,finger pads produce mechanical offspring, they always have single$-$thickness finger pads. When two pencils with triple$-$thickness finger pads produce mechanical offspring, they always have triple$-$thickness finger pads. When two pencils with double$-$thickness finger pads produce mechanical offspring, they have double$-$thickness finger pads $50\%$ of the time, singlethickness finger pads $25\%$ of the time, and triple$-$thickness finger pads $25\%$ of the time.

thickness of finger pad appears to be determined by the $W$ gene. whether a pencil is mechanical or traditional appears to be determined by the $B$ gene.

Pencils that are traditional express a non$-$functional allele of the $B$ gene, which suppresses any form of expression of the $W$ gene.

Interestingly, pencils with non$-$functional $B$ alleles have a number of other traits associated with the lack of mechanization, including being yellow and being made of wood.

For all questions about these traits, assume there are no de novo $($new$)$ mutations appearing between generations.

Question:

There is a family of pencils with $8$ offspring where:

$4$ of the offspring are traditional

$2$ have double$-$thickness finger pads

$1$ has a triple$-$thickness finger pad

$1$ has a single$-$thickness finger pad

Based on this, the likely genotypes of the parents are: