A pure-breeding white mouse with a long tail was crossed to pure-breeding pink mouse with a short tail. The F1 progeny were all pink with long tails. These F1 mice were test crossed to white mouse with a short tail.

If the gene controlling color and the gene controlling tail length in mice are very closely linked, what phenotypes are expected to be the most frequent in the progeny of the test cross?

Pink, short tail and white, long tail

There is not enough information to make a prediction.

Pink, short tail and white, short tail

Pink, long tail and white, short tail

Pink, long tail and white, long tail

Well, if the genes controlling color and tail length in mice are very closely linked, we can expect that these traits will be inherited together more often. So, in the progeny of the test cross, the most frequent phenotypes would likely be pink with a long tail and white with a short tail. Just imagine little mice strutting around with their long pink tails or short white tails. It's quite a sight!

If the genes controlling color and tail length in mice are very closely linked, we would expect the phenotypes that were inherited together in the F1 generation to be the most frequent in the progeny of the test cross.

In this case, the F1 generation had pink mice with long tails, suggesting that the alleles for pink color and long tail are closely linked.

Therefore, the most frequent phenotypes in the progeny of the test cross would be pink with long tails and white with short tails, as these are the phenotypes that were inherited together in the F1 generation.

So, the answer is: Pink, long tail and white, short tail.

To determine the most frequent phenotypes in the progeny of the test cross, we need to understand the concept of genetic linkage. Genetic linkage refers to the tendency of genes located on the same chromosome to be inherited together more frequently than expected by chance.

In this case, if the gene controlling color (white vs. pink) and the gene controlling tail length (long vs. short) are very closely linked, they are more likely to be inherited together. Let's represent the gene for color as A (white) and a (pink), and the gene for tail length as B (long) and b (short).

Based on the information provided in the question, the F1 generation resulting from crossing the pure-breeding parents (white with long tail and pink with short tail) were all pink with long tails. This indicates that the white allele (A) for color and the long allele (B) for tail length are recessive.

Now, let's consider the test cross between the F1 mice (pink with long tail) and the white mice with short tails. If the genes controlling color and tail length are very closely linked, they are expected to be inherited together more frequently.

Since the F1 mice are pink with long tails, we can infer that they are heterozygous for both color and tail length (AaBb). When crossed with the white mice with short tails (aaBb), the possible phenotypes and their frequencies in the progeny can be determined using Punnett squares or by applying the principles of Mendelian genetics.

The possible combinations of alleles in the progeny are:
- AaBb (pink with long tails)
- Aabb (pink with short tails)
- aaBb (white with long tails)
- aabb (white with short tails)

Since the F1 mice are pink with long tails (AaBb), the most frequent phenotypes in the progeny of the test cross would be pink with long tails (AaBb) and white with short tails (aabb). These phenotypes are the most likely if the genes controlling color and tail length are very closely linked.

Therefore, the correct answer is: Pink, long tail and white, short tail.