Video Transcript
Which of the following statements
would correctly replace X in the Venn diagram comparing the classes Sarcodina and
Sporozoa? (A) Move using flagella that extend
from the cell. (B) Move by beating cilia
surrounding the cell. (C) Have multiple, varied
appendages for locomotion. Or (D) Move using extensions called
pseudopodia.
This question is asking us to
compare two classes of organisms using a tool called a Venn diagram. The classes Sarcodina and Sporozoa
are both contained in the phylum Protozoa, which is part of the protist kingdom.
In a Venn diagram, we can compare
and contrast two or more different topics. The circle on the right represents
the class Sporozoa. Information in this circle is true
about organisms that are classified as Sporozoa. The circle on the left represents
the class Sarcodina. Information in this circle is true
about organisms that are classified as Sarcodina. The two circles overlap in the
middle. Information in this space is true
about both class Sporozoa and class Sarcodina.
So, we know that we need to choose
the answer that is true about class Sarcodina and not Class Sporozoa. There are four main classes within
the phylum Protozoa. They are Flagellata, Ciliophora,
Sporozoa, and Sarcodina. These four classes are
distinguished by how their member organisms move, or their method of locomotion.
Members of class Flagellata move
using an organelle called flagella. Members of class Ciliophora move
using organelles called cilia. We can see in our diagram that
Sporozoa have no specialized organelles for locomotion. So, what about class Sarcodina? We can use what we have recalled so
far to eliminate the statement “move using flagella that extend from the cell.” We can also eliminate the statement
that says “move by beating cilia surrounding the cell.” We know that these are
characteristics of the Flagellata and Ciliophora classes.
In the Venn diagram, we can see
that an amoeba is an example of an organism in the class Sarcodina. You might recall that amoeba are
unicellular protozoans that move by extending portions of their cell body. We call one of these extensions a
pseudopod. Pseudopod is a word that means
“false foot.”
So, the statement that would
correctly replace X in the diagram is “move using extensions called
pseudopodia.”
