Chapter 28: Protista

Vocabulary practice flashcards covering the major concepts, evolutionary supergroups, cellular structures, nutritional strategies, and life cycles in Chapter 28: Protista.

Protists

Eukaryotic organisms that are not classified in the plant, animal, or fungal kingdoms; most are microscopic and abundant in moist habitats.

Algae

A major ecological category of protists that are generally photoautotrophic.

Protozoa

A major ecological category of protists characterized by heterotrophic nutrition.

Fungus-like protists

Heterotrophic protists that resemble true fungi in their body form and absorptive nutrition.

Plankton

Aquatic organisms that swim weakly or float in water, encompassing protists, bacteria, viruses, and small animals.

Periphyton

Communities of microorganisms attached to submerged surfaces by mucilage or other adhesives.

Flagellates

Protists that swim by means of eukaryotic flagella.

Ciliates

Protists that move using cilia, which are typically shorter and more abundant than flagella.

Amoebae

Protists that move and feed using cytoplasmic extensions known as pseudopodia.

Excavata

A eukaryotic supergroup composed of unicellular flagellates that are often characterized by a feeding groove used to ingest prey via phagocytosis.

Metamonada

A subgroup of Excavata consisting of flagellates with modified mitochondria, including the parasites Giardia intestinalis and Trichomonas vaginalis.

Kinetoplast

A distinctive, large mass of mitochondrial DNA found within the single mitochondrion of kinetoplastids such as Trypanosoma brucei.

Euglenida

A group of excavates possessing protein strips beneath the cell surface, an eyespot, carbohydrate-storage particles, and sometimes secondary plastids derived from green algae.

Primary endosymbiosis

The evolutionary process whereby a nonphotosynthetic eukaryotic host engulfs a cyanobacterium, giving rise to a primary plastid enclosed by two envelope membranes.

Secondary endosymbiosis

The process in which a eukaryotic protist engulfs an endosymbiotic red or green alga and retains its plastid, producing a secondary plastid with more than two envelope membranes.

Tertiary endosymbiosis

The endosymbiotic process in which a predatory protist (such as a dinoflagellate) engulfs a eukaryotic protist harboring a secondary plastid, retaining it as a multiple-membraned tertiary plastid.

Rhodophyta

The phylum of red algae within the Land Plants and Relatives supergroup, possessing primary plastids with two envelope membranes.

Alveoli

Membrane-bound sacs situated directly beneath the plasma membrane that distinguish members of the supergroup Alveolata.

Apicomplexa

A phylum of parasitic alveolates, including Plasmodium falciparum and Cryptosporidium parvum, that often possess nonphotosynthetic secondary plastids.

Dinozoa (dinoflagellates)

Alveolates characterized by cellulose-filled alveoli, distinct flagellar arrangements, and diverse secondary or tertiary plastids, sometimes causing harmful red tides.

Stramenopila

A eukaryotic supergroup characterized by strawlike flagellar hairs and plastids typically acquired via secondary endosymbiosis from red algae.

Fucoxanthin

A characteristic accessory carotenoid pigment common in photosynthetic stramenopiles, including diatoms and brown algae.

Bacillariophyceae (diatoms)

Photosynthetic stramenopiles with ornate silicate cell walls that reproduce asexually until shrinking below a critical threshold size, which triggers sexual reproduction.

Rhizaria

A eukaryotic supergroup featuring thin, hair-like cytoplasmic projections known as filose pseudopodia.

Amoebozoa

A eukaryotic supergroup that moves using blunt pseudopodia, encompassing species such as Entamoeba histolytica and slime molds like Dictyostelium discoideum.

Choanomonada (choanoflagellates)

Opisthokont protists characterized by swimming cells possessing a single posterior flagellum encircled by a collar of cellular extensions.

Phagotrophy

A heterotrophic feeding mechanism in which cells engulf food particles into vesicles via phagocytosis.

Osmotrophy

A form of heterotrophic nutrition that relies on absorbing dissolved organic molecules directly across the plasma membrane.

Mixotrophy

The nutritional ability to switch between or combine photoautotrophy and heterotrophic feeding (phagotrophy or osmotrophy) according to conditions.

Extrusomes

Spear-shaped projectile organelles ejected from the periphery of protist cells to discourage predators or capture prey.

Cysts

Dormant cell forms encased in thick, protective walls that allow protists to endure unfavorable conditions and aid in parasite transmission.

Alternation of generations

A sporic sexual life cycle in which a multicellular haploid ($n$) gametophyte generation alternates with a multicellular diploid ($2n$) sporophyte generation.