Critical Thinking Questions
23. Describe the hypothesized steps in the origin of eukaryotic cells.
24. Some aspects of eukaryotes are more similar to Archaea, while other aspects of eukaryotic cell composition appear more closely related to Bacteria. Explain how endosymbiosis could resolve this paradox.
25. Explain in your own words why sexual reproduction can be useful if a protist’s environment changes.
26. 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?
27. 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.
28. The chlorophyte (green algae) genera Ulva and Caulerpa both have macroscopic leaf-like and stem-like structures, but only Ulva species are considered truly multicellular. Explain why.
29. Why might a light-sensing eyespot be ineffective for an obligate saprobe? Suggest an alternative organ for a saprobic protist.
30. Opisthokonta includes animals and fungi, as well as protists. Describe the key feature of this phylum, and an example of how an organism in each kingdom uses this feature.
31. Describe two ways in which paramecium differs from the projected traits of the last eukaryotic common ancestor.
32. How does killing Anopheles mosquitoes affect the Plasmodium protists?
33. Without treatment, why does African sleeping sickness invariably lead to death?
34. Describe how increasing stress to the ocean would affect a food chain containing zooxanthellae, corals, parrotfish, and sharks.