Kingdom Protista

Kingdom Protista: Characteristics Mostly unicellular, eukaryotic cells Reproduce asexually or sexually by conjugation Exhibit all three modes of nutrition Photosynthesis Ingestion Absorption Ultimately spawned all multicellular kingdoms Very diverse kingdom Difficult for taxonomists to agree on classification Diverse Modes of Nutrition Use diverse modes of nutrition Ingest food Absorb nutrients from surroundings Photosynthesis Protists that ingest food are typically predators Use extensions of cell membrane called psuedopods to surround and engulf prey item Diverse Modes of Nutrition Protists that absorb nutrients directly from the surrounding environment can be Free-living types in the soil that decompose organic dead matter Parasites that live inside the bodies of other organisms, sometimes harming the host Diverse Modes of Nutrition Some protists have photosynthetic organelles called chloroplasts Photosynthetic protists are abundant in oceans, lakes, and ponds Free floating Mutually beneficial associations with other organisms: solar energy captured by the protist is used by host, which shelters and protects the protist Diverse Modes of Nutrition Photosynthetic protists are collectively known as algae Single-celled, non-photosynthetic protists are collectively known as protozoa Diverse Modes of Reproduction Most protists reproduce asexually by mitotic cell division Some also reproduce sexually Two individuals contribute genetic material to an offspring that is genetically different from either parent Occurs during certain time of year or circumstances (e.g. a crowded environment or a food shortage)