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, I must say, genetics can be quite a tail-winding adventure. But let's unravel this one, shall we? So, if the gene controlling color and the gene controlling tail length in mice are very closely linked, we would expect the most frequent phenotypes in the progeny of the test cross to be pink with a short tail and white with a long tail. After all, sometimes it's all in the genes, especially when it comes to mice and their fancy tails. So, put on your coat and let's see what the test cross has in store!
If the genes controlling color and tail length in mice are very closely linked, the most frequent phenotypes in the progeny of the test cross are expected to be Pink, long tail and White, short tail.
To determine the phenotypes that are expected to be the most frequent in the progeny of the test cross, we need to understand the concept of genetic linkage and the results of the previous crosses.
In the first cross between a pure-breeding white mouse with a long tail and a pure-breeding pink mouse with a short tail, the F1 progeny were all pink with long tails. This indicates that the gene controlling color and the gene controlling tail length are on the same chromosome and are very closely linked.
In the test cross, the F1 mice (pink with long tails) are crossed with a white mouse with a short tail. The phenotype of the F1 mice is determined by their genotype, which is unknown in this case. However, since the gene controlling color and tail length are closely linked, they are likely to be inherited together more often than not.
Therefore, the most frequent phenotypes expected in the progeny of the test cross would be pink with long tails (inherited together from the F1 parent) and white with short tails (inherited from the white mouse parent). The answer would be "Pink, long tail and white, short tail."