Video Transcript
Many bulbous plants, like the one
pictured, have contractile, pulling, roots. What is the primary function of
these contractile roots? (A) To pull the bulb lower into the
ground. (B) To attract useful fungal
species to the bulb. (C) To increase the bulb’s exposure
to light. Or (D) to expel excess water from
the bulb.
Although plants might seem like
they don’t move, they’re actually capable of several different kinds of movement,
which can help the plant in several ways. Sometimes, a plant might show
movement to obtain the natural resources it needs, like water or sunlight. In other cases, some plants might
show some form of movement or growth response to protect themselves from herbivores
or environmental conditions.
Our question mentions contractile
roots in bulbous plants. This is an example of a plant that
shows a form of movement in order to protect itself from the environment.
Let’s learn a little bit more about
how these contractile roots work. Contractile roots are thickened
root structures that are capable of shrinking under harsh environmental conditions,
like seasonal drought. As a plant grows, its roots grow
deeper and deeper into the soil. If there is a drought, these roots
will shrink, which exerts a strong downward pull on the bulb of the plant, which is
why contractile roots are sometimes referred to as pulling roots. By pulling the bulb downward and
positioning it deeper into the ground, the contractile roots function to protect the
plant from extreme weather conditions.
Therefore, the correct answer to
this question is (A), to pull the bulb lower into the ground.
