Video Transcript
Organisms can reproduce sexually or
asexually. Which of the following could
threaten the continuity of a population of rabbits but not a population of
yeast? (A) There is a sudden change in the
environment. (B) There is a disease present
within the population. (C) Members of a species are
isolated from each other. (D) There are more breeding sites
than there are breeding pairs. Or (E) there is a decrease in
nutrient availability.
This question is asking us to
figure out which of the factors mentioned in the answer options could threaten a
population of rabbits but not a population of yeast. It mentions the two types of
reproduction, sexual reproduction and asexual reproduction. Let’s explore what these key terms
mean and how they might affect populations of rabbits and yeast so that we can work
out the correct answer.
Sexual reproduction is a method of
producing offspring whereby two gametes that are usually produced by two parents
fuse in a process called fertilization. This tends to produce a zygote,
which can then develop, grow, and differentiate into a fully formed organism. As sexual reproduction usually
involves two parents combining their genetic material, it produces offspring with a
fairly high genetic variation. This provides populations that
utilize this form of reproduction with resilience to environmental changes. However, sexual reproduction is
fairly slow. And as it usually requires two
parents, these two organisms must be located fairly close together. Rabbits are examples of organisms
that can only reproduce through sexual reproduction.
Asexual reproduction only involves
one parent. The offspring produced through
asexual reproduction are genetically identical. While this process is much faster
than sexual reproduction, partly as it does not require an organism to find a mate
to reproduce with, as offspring are identical, genetic variation is fairly low.
Yeast are single-celled fungi which
can reproduce either sexually or asexually. This is really useful as if
individual yeast cells are isolated from each other, they will still be able to
reproduce asexually. It also means that if there’s a
sudden change in the environment or a new disease is introduced to the population,
the yeast cells can reproduce sexually. This acts to increase the genetic
variation in their offspring and hopefully introduce new useful traits to aid
survival in these changing conditions.
However, if no rabbits are able to
access mates to reproduce with, sexual reproduction will not be able to occur. So the rabbits will not be able to
reproduce at all. This could definitely threaten the
continuity of a population of rabbits. This means that we’ve found the
correct answer to this question. The scenario that could threaten
the continuity of the population of rabbits but not a population of yeast is
(C). Members of a species are isolated
from each other.