Characteristics of Protists

Free Response

Explain in your own words why sexual reproduction can be useful if a protist’s environment changes.

Hint:

The ability to perform sexual reproduction allows protists to recombine their genes and produce new variations of progeny that may be better suited to the new environment. In contrast, asexual reproduction generates progeny that are clones of the parent.

Giardia lamblia is a cyst-forming protist parasite that causes diarrhea if ingested. Given this information, against what type(s) of environments might G. lamblia cysts be particularly resistant?

Hint:

As an intestinal parasite, Giardia cysts would be exposed to low pH in the stomach acids of its host. To survive this environment and reach the intestine, the cysts would have to be resistant to acidic conditions.

Explain how the definition of protists ensures that the kingdom Protista includes a wide diversity of cellular structures. Provide an example of two different structures that perform the same function for their respective protist.

Hint:

Protists are defined as any eukaryotes that do not fall into the Plantae, Fungi, or Animal Kingdoms. Since the unifying characteristics describe what they are NOT, rather than what they are, Protista can include almost any cellular/organism organization. Possible examples of structure variety:

  • Barrier to exterior world: cell wall, plasma membrane, pellicle
  • Locomotion: flagella, cilia, pseudopodia