Chapter 26, Problem 15STP

Summary Introduction

To write:The theory of endosymbiosis as it applies to protists.

Introduction:Protists are more readily categorized by what they are not, than by what they are. Protists aren't animals, plants, or fungi because they don't have all the requisite characteristics to put them in any of these domains. As with all eukaryotes, protists DNA is present inside the membrane-bound nucleus.

Explanation of Solution

The endosymbiosis hypothesis was brought forward by Lynn Margulis. This theory suggests that eukaryotes were formed when a massive prokaryote engulfed a smaller prokaryote, including protists. The two species go to symbiotic life. The species gradually merged into a single, more fully formed host.Some scientists assume that once individual organisms were the mitochondria and chloroplasts present in some eukaryotes and protists. All the protists have one common eukaryotic ancestral cell. Later in the developmental process, Mitochondria became a part of protist cells. Algae are the only chloroplastic protists that undergo photosynthesis.

Conclusion

Thus, it concludes thatall protists have one common eukaryotic ancestral cell.