Video Transcript
From left to right, the pictures
show the following organisms of the animal kingdom: Planaria; a sponge;
Hydra; a starfish, sea star; and an ant. Which of the organisms shown in the
pictures is unable to regenerate and form two individuals when its body is cut in
half? (A) Planaria, (B) sponge,
(C) Hydra, (D) starfish, or (E) ant.
Reproduction is a biological
process by which a parent, or parents, produce offspring. Reproduction can occur sexually or
asexually. You may be more familiar with
sexual reproduction, which usually occurs when two parents each produce gametes that
fuse to produce a zygote. This often results in high levels
of genetic variation and helps to provide populations with greater resilience to
changing environmental conditions.
Some species can reproduce
asexually, which creates offspring that are genetically identical to the single
parent that created them. While this is much faster than
sexual reproduction, it produces offspring with comparatively lower genetic
variation. Asexual reproduction can occur
through a variety of methods: binary fission, budding, regeneration,
parthenogenesis, sporogenesis, or vegetative propagation.
For this question, we are looking
specifically at regeneration, which is where organisms can repair or regrow damaged
or missing parts of their bodies. Let’s take a closer look at this
process.
We can see that this starfish has
been cut in half. Each of these halves is able to
regrow into a complete starfish again, resulting in two genetically identical
organisms. Many organisms are able to
regenerate. Some common examples which have
been shown in this question are the Hydra, Planaria, starfish, and
sponge.
The correct answer to this question
is therefore answer option (E). The organism which has been shown
in the pictures that is unable to regenerate and form two individuals when its body
is cut in half is the ant.
