BIO153H5 Chapter Notes - Chapter 29: Nuclear Dna, Brown Algae, Paraphyly
Document Summary
Protists are paraphyletic grouping that includes all eukaryotes except the green plants, fungi, and animals. Biologists study protists to understand how eukaryotes evolved, because they are important in freshwater and marine ecosystems and global arming, and because some species cause debilitating diseases in plants, humans and other organisms. They vary in the types of organelles they contains; they may be unicellular or multicellular, and they may have a cell wall other external covering, or no such covering. Protists vary widely in terms of how the find food. Many species are photosynthetic, while others obtain carbon compounds by ingesting food or parasitizing other organisms. Protists vary widely in terms of how they reproduce. Sexual reproduction evolved in protists, and many protists species can reproduce both sexually and asexually. Eukarya range from single-celled organisms that are the size of bacteria to sequoia trees and blue whales.
