Video Transcript
It is difficult for mules to make
gametes because they have an odd number of chromosomes. What does this lead to? (A) This leads to mules being
considered extinct animals. (B) This leads to mules being found
in a certain habitat. (C) This leads to mules not being
considered a species. Or (D) this leads to mules being
different from their parents in appearance.
A mule is the offspring of a female
horse and a male donkey. Though horses and donkeys are
different species, in this case they are similar enough that they are able to
produce offspring. However, they do have different
numbers of chromosomes so that the mule offspring ends up inheriting an odd number
of chromosomes. This makes it difficult for the
chromosomes to divide equally during meiosis, and therefore makes it difficult for
the mule to produce viable gametes. If the mule can’t produce viable
gametes, it can’t produce its own offspring. We therefore describe mules as
infertile.
In fact, part of what makes horses
and donkeys clearly different species is the fact that, while they can produce
offspring, their offspring are infertile and can’t produce offspring of their
own. Since mules can’t reproduce, they
are also not considered their own species, but rather just a hybrid of two
species.
So, the correct answer to this
question is (C). Mules having difficulty making
gametes leads to mules not being considered a species.
