College

Select the correct answer from each drop-down menu.

1. If a heterozygous male with the genotype [tex]Ww[/tex] is mated with a homozygous recessive female of genotype [tex]ww[/tex], there is a chance that [tex]25\%[/tex] of the offspring will be heterozygous.

[tex]
\[
\begin{array}{|c|c|c|}
\hline
& w & w \\
\hline
w & Ww & ww \\
\hline
w & Ww & ww \\
\hline
\end{array}
\]
[/tex]

2. If a heterozygous [tex]Ww[/tex] is crossed with a homozygous dominant [tex]WW[/tex], then the probability of having a homozygous recessive offspring is 0%.

[tex]
\[
\begin{array}{|c|c|c|}
\hline
& W & W \\
\hline
W & WW & Ww \\
\hline
W & WW & Ww \\
\hline
\end{array}
\]
[/tex]

Answer :

Let’s analyze each cross step by step.


Step 1. Cross Between a Heterozygous Male and a Homozygous Recessive Female

The male has the genotype
[tex]$$Ww,$$[/tex]
and the female has the genotype
[tex]$$ww.$$[/tex]

The male can contribute either the [tex]$W$[/tex] allele or the [tex]$w$[/tex] allele with equal probability, while the female can only contribute the [tex]$w$[/tex] allele. We set up a Punnett square as follows:

[tex]$$
\begin{array}{c|cc}
& w & w \\
\hline
W & Ww & Ww \\
w & ww & ww \\
\end{array}
$$[/tex]

Each box represents a possible combination of alleles in the offspring. Here, two of the four outcomes are heterozygous ([tex]$Ww$[/tex]) and two are homozygous recessive ([tex]$ww$[/tex]).

Thus, the probability that an offspring will be heterozygous is

[tex]$$\frac{2}{4} \times 100\% = 50\%.$$[/tex]


Step 2. Cross Between a Homozygous Dominant and Another Homozygous Dominant

For the second situation, both parents have the genotype
[tex]$$WW.$$[/tex]

Since each parent can only contribute the [tex]$W$[/tex] allele, all offspring will receive a [tex]$W$[/tex] allele from each parent. The Punnett square for this cross is:

[tex]$$
\begin{array}{c|cc}
& W & W \\
\hline
W & WW & WW \\
W & WW & WW \\
\end{array}
$$[/tex]

Every box in the Punnett square shows the genotype [tex]$WW$[/tex]. This means that no offspring will be homozygous recessive ([tex]$ww$[/tex]).

Thus, the probability of having a homozygous recessive offspring is

[tex]$$0\%.$$[/tex]


Final Answer:

1. The probability that an offspring will be heterozygous from the first cross is [tex]$\boxed{50\%}.$[/tex]
2. The probability of having a homozygous recessive offspring from the second cross is [tex]$\boxed{0\%}.$[/tex]