Video Transcript
Which of the following organisms
would not be classified into the kingdom Plantae? (A) Conifer, (B) moss, (C) fern, or
(D) yeast.
This question is asking us about
the organisms in the kingdom Plantae, so let’s start by reviewing some of the key
facts about this kingdom. There is an incredibly diverse
range of organisms on Earth. To make it easier to study them,
scientists have classified them into groups, a process known as taxonomy. In 1969, the scientist Robert
Whittaker proposed the five-kingdom classification system. This placed all organisms into one
of the following kingdoms: Monera, Protista, Fungi, Plantae, and Animalia, according
to their characteristics.
As the question focuses on the
kingdom Plantae, let’s look at this kingdom more closely. Nearly 400,000 different species of
plants have been identified in the kingdom Plantae. But they are all linked by some
common characteristics. These characteristics are important
for classification. Let’s review them so that we can
answer the question correctly.
All plants are eukaryotic, which
means their cells have a nucleus and other membrane-bound organelles. For structure and support, they
have cell walls made of cellulose around the outside of the cell. They are autotrophic, which means
they make their own food. They do this by the process called
photosynthesis whereby carbon dioxide and water are converted into sugars, such as
glucose, and oxygen in the presence of sunlight. This occurs in the chloroplasts,
which are organelles containing the green pigment chlorophyll to absorb the
sunlight.
Having reviewed some of the key
characteristics of plants, let’s return to our question and approach each option to
determine which organism does not have these specific characteristics.
Conifers, such as firs and pines,
belong to the class Gymnospermae. They are vascular trees and shrubs
that are evergreen and have needlelike leaves. They contain chloroplasts so
photosynthesize and are classified in the kingdom Plantae. This means option (A) is
incorrect.
Mosses belong to the phylum
Bryophyta, which are nonvascular plants. They are green, as their leaves
contain chlorophyll, so they can photosynthesize. They may have structures called
rhizoids to help anchor the plant into the ground. They form dense green mats in shady
damp locations. As they are also plants, option (B)
can be eliminated.
Ferns belong to the class
Filicatae. They are green and also
photosynthesize. Most ferns are found as herbs. Some are shrubs or trees. They have stems, leaves, and roots
and reproduce via spores. Ferns are also classified as
plants, so option (C) is incorrect.
Yeast are eukaryotic single-celled
organisms. Their cell wall is made of chitin,
not cellulose. They do not have chloroplasts so
cannot photosynthesize. Instead, they have to feed
saprophytically by secreting digestive enzymes onto their food and absorbing the
products. They do not belong to the kingdom
Plantae. They are members of the kingdom
Fungi. So the correct answer is (D). The organism that would not be
classified into the kingdom Plantae is yeast.