In mice, the gene for tail length has two alleles. A long tail is dominant to a short tail. If a long-tailed mouse that is heterozygous mates with a short-tailed mouse, what are the chances of having offspring with short tails?(1 point)

Question

Responses

25%
25%

50%
50%

100%
100%

75%

Answer 1

To determine the chances of having offspring with short tails, we need to understand the genotypes involved.

Let's denote:

• \( L \) = allele for long tail (dominant)
• \( l \) = allele for short tail (recessive)

A long-tailed mouse that is heterozygous would have the genotype \( Ll \), while a short-tailed mouse, which expresses the recessive trait, has the genotype \( ll \).

When these two mice mate, we can set up a Punnett square to find the genotypes of the potential offspring:

\[ \begin{array}{c|c|c} & l & l \ \hline L & Ll & Ll \ \hline l & ll & ll \ \end{array} \]

From the Punnett square, the possible genotypes of the offspring are:

• \( Ll \) (long-tailed) - 2 occurrences
• \( ll \) (short-tailed) - 2 occurrences

Thus, out of 4 total offspring:

• 2 will have the long-tail genotype (Ll)
• 2 will have the short-tail genotype (ll)

The probability of having offspring with short tails (genotype \( ll \)) is \( \frac{2}{4} \) or \( 50% \).

So, the answer is 50%.