Answered

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}{|l|l|l|}
\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. 1 long, 3 short
B. 4 long, 0 short
C. 3 long, 1 short
D. 2 long, 2 short



Answer :

To determine the phenotype ratio from the given Punnett square for cats with short and long tails, we need to analyze the genotypes provided. Short tails are dominant (represented by [tex]$T$[/tex]), and long tails are recessive (represented by [tex]$t$[/tex]). Here's the breakdown of the Punnett square:

[tex]\[ \begin{array}{|c|c|c|} \hline & T & t \\ \hline t & Tt & tt \\ \hline t & Tt & tt \\ \hline \end{array} \][/tex]

The Punnett square shows the following possible genotypes for the offspring:
1. [tex]$Tt$[/tex]
2. [tex]$tt$[/tex]
3. [tex]$Tt$[/tex]
4. [tex]$tt$[/tex]

Now, let's determine the phenotypes for these genotypes:
- [tex]$Tt$[/tex]: This genotype contains one dominant allele (T) and one recessive allele (t). Since the dominant allele T is present, the phenotype will be short tails.
- [tex]$tt$[/tex]: This genotype contains two recessive alleles (t). The absence of the dominant allele means the phenotype will be long tails.

From the Punnett square, we have:
- [tex]$Tt$[/tex] (short tails) appears 2 times.
- [tex]$tt$[/tex] (long tails) appears 2 times.

Therefore, the phenotype ratio for short tails to long tails is 2 short, 2 long.

So the correct answer is:
D. 2 long, 2 short