Video Transcript
Which plant characteristic allows
large numbers of clones to be produced by tissue culture? (A) Plants are able to grow
structures such as bulbs and runners that form identical offspring. (B) Plant cells can be stimulated
to grow and differentiate to form a complete organism. (C) Plants can produce large
numbers of seeds at one time that can be dispersed over a large area. (D) Plants use a variety of
methods, such as wind and insects, to promote pollination. Or (E) plants can switch between
asexual and sexual reproduction depending on the environmental conditions.
We can see the key terms clones and
tissue culture in the question, which tells us that this question deals with asexual
reproduction in plants. Asexual reproduction can happen
through a variety of methods, such as binary fission, budding, regeneration,
sporogenesis, parthenogenesis, and vegetative propagation. Vegetative propagation refers to a
type of asexual reproduction found only in plants and some algae. So let’s look more closely at this
method.
Vegetative propagation is the
production of plant clones from parts of a parent plant. Depending upon the species of
plant, the offspring can arise from stems, bulbs, runners, roots, tubers, leaves, or
even fruits, as shown in the diagram of a prickly pear cactus. Under the right environmental
conditions, the fallen plant parts will take root and develop into new
individuals. However, because vegetative
propagation is a form of asexual reproduction, these offspring will not be
genetically unique but rather are clones of their parent plant.
Sometimes scientists need to
cultivate plants in a controlled environment. For example, they might want to
conduct research on plant varieties that are resistant to disease or drought or have
medicinal properties.
Tissue culture is a technique that
allows this type of research to take place. It involves taking a sample of
cells from living tissue, such as a plant leaf, and growing them in a controlled
laboratory setting, typically on a special growth medium that contains essential
plant nutrients. Hormones may be added to the growth
medium to encourage the development of the cells. Interestingly, coconut water can
sometimes be used as a growth medium because it contains nutrients and growth
hormones that are essential for some plant species.
By relying on the same biological
pathways used in vegetative propagation, scientists can stimulate the plant cells to
grow and differentiate into whole organisms that can be transplanted for use in
research studies. And because all the plants are
clones, tissue culture allows the scientists to control for genetic differences
between individual plants.
Returning to our answer options, we
can see that although all of them contain true statements about plants, only option
(B) accurately describes the characteristic that allows large numbers of clones to
be produced through tissue culture. So the correct answer choice is
(B). Plant cells can be stimulated to
grow and differentiate to form a complete organism.
