Video Transcript
A student writes the following
summary about sexual reproduction. Sexual reproduction is the process
by which two organisms mate and produce genetically unique offspring. It produces new offspring very
quickly. What is incorrect about this
statement? (A) Sexual reproduction does not
always involve two parents; it can sometimes involve only one or more than two. (B) Sexual reproduction is a
time-consuming process, as individuals need to find mates and incubate their
young. Or (C) sexual reproduction produces
offspring that are identical to the parents, not genetically unique.
The question gives us a
hypothetical summary of sexual reproduction and asks us to identify the inaccuracy
in the statements. Let’s begin by reviewing the
defining characteristics of sexual and asexual reproduction.
Sexual reproduction requires the
fusion of a male and female gamete in a process called fertilization, which results
in a zygote. The gametes typically come from two
different parents. The resulting offspring will be
genetically unique because it receives half its genetic information from its
biological mother and half from its biological father. This means that sexual reproduction
has the advantage of increasing the genetic variation of a population. However, it is a relatively slow
process because of the time needed to find a mate, for fertilization to occur, and
for the gestation or incubation period.
Asexual reproduction requires just
one parent and does not involve the fusion of gametes. One of the most common methods of
asexual reproduction is binary fission, in which a parent cell replicates its
genetic information and then splits into two identical daughter cells. Asexual reproduction tends to be
faster than sexual reproduction because no time is required to find a mate, for
fertilization, or for an incubation or gestation period. For example, some bacteria can
complete binary fission in a mere 20 minutes. In contrast, the total gestation
period of humans, that is, the time from fertilization to birth, is about 38
weeks. It may be speedy, but asexual
reproduction does have a major disadvantage. The resulting offspring are usually
genetic clones. So asexual reproduction does not
increase genetic variation.
We now have the information we need
to correct the summary of sexual reproduction. The first sentence is correct
because, as we discussed, sexual reproduction typically involves two organisms, the
parents, and does produce genetically unique offspring. However, we also learned that
sexual reproduction is more time-consuming than asexual reproduction. So the second sentence is
incorrect. Looking over the answer choices, we
can see that option (B) provides the correction for this statement. Sexual reproduction is a
time-consuming process, as individuals need to find mates and incubate their
young.
