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For a certain breed of cat, short tails are dominant [tex]$(T)$[/tex] and long tails are recessive [tex]$(t)$[/tex]. The Punnett square below shows a cross between two parents. What is the phenotype ratio for this cross?

\begin{tabular}{|c|c|c|}
\hline & [tex]$T$[/tex] & [tex]$t$[/tex] \\
\hline [tex]$t$[/tex] & [tex]$T t$[/tex] & [tex]$t t$[/tex] \\
\hline [tex]$t$[/tex] & [tex]$T t$[/tex] & [tex]$t t$[/tex] \\
\hline
\end{tabular}

A. 3 long, 1 short
B. 2 long, 2 short
C. 4 long, 0 short
D. 1 long, 3 short



Answer :

GinnyAnswer
To determine the phenotype ratio for the given cross, we need to analyze the Punnett square and see the types of offspring produced from the cross between the two parent cats.

The given Punnett square is:
[tex]\[ \begin{tabular}{|c|c|c|} \hline & T & t \\ \hline t & Tt & tt \\ \hline t & Tt & tt \\ \hline \end{tabular} \][/tex]

First, we identify the genotypes that result from this cross:

1. Upper left cell: Offspring with genotype [tex]\(Tt\)[/tex] (short tail, because [tex]\(T\)[/tex] is dominant over [tex]\(t\)[/tex])
2. Upper right cell: Offspring with genotype [tex]\(tt\)[/tex] (long tail)
3. Lower left cell: Offspring with genotype [tex]\(Tt\)[/tex] (short tail)
4. Lower right cell: Offspring with genotype [tex]\(tt\)[/tex] (long tail)

Now, let's count the number of each genotype:

- [tex]\(Tt\)[/tex] appears in 2 cells.
- [tex]\(tt\)[/tex] appears in 2 cells.

Next, we determine the phenotypes. Since [tex]\(T\)[/tex] (short tail) is dominant over [tex]\(t\)[/tex] (long tail):

- The [tex]\(Tt\)[/tex] genotype results in short tails.
- The [tex]\(tt\)[/tex] genotype results in long tails.

Counting the phenotypes:

- Short tails ([tex]\(Tt\)[/tex]): 2
- Long tails ([tex]\(tt\)[/tex]): 2

Therefore, the phenotype ratio for this cross is:

2 short tails : 2 long tails

This corresponds to the ratio option:

B. 2 long, 2 short

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