Video Transcript
Fill in the blank. The unicellular organism
Euglena has a blank to help it move toward the light. (A) Nucleus, (B) chloroplast, (C)
vacuole, (D) pseudopodium, or (E) flagellum.
Euglena is a unicellular, or
single-celled, organism. It is an especially interesting
organism, as in spite of being single celled, it is able to photosynthesize much
like a plant would. Remember, photosynthesis is the
process by which some organisms are able to use light energy and simple inorganic
molecules to produce their own food in the form of sugars.
Euglena cells can carry out
photosynthesis thanks to organelles they contain called chloroplasts. Photosynthetic pigments like
chlorophyll that are found in these chloroplasts allow both plants and
photosynthetic unicellular organisms like Euglena to capture light
energy. Euglena cells have several
adaptations that allow them to access light efficiently. This means that they can maximize
the amount of food they make through photosynthesis. For instance, these cells tend to
contain a structure called an eyespot. This primitive eye enables them to
be sensitive to their environment and detect light. But how do the Euglena cells
move toward light once they’ve sensed it?
Well, Euglena cells are able
to move fairly quickly using whiplike tails called flagella. A single flagella is called a
flagellum. Flagella allow the Euglena
cells to quickly move in the direction of light when they sense it, maximizing the
efficiency of photosynthesis. This means that we know the
structure that Euglena cells have that helps them move toward light, and
therefore the answer to this question. The correct answer is (E),
flagellum.
