Eukaryotic Origins & Endosymbiosis
What two key features distinguish eukaryotes from prokaryotes?
Presence of a nucleus and membrane-bound organelles.
Are protists monophyletic, paraphyletic, or polyphyletic?
Paraphyletic—not all descendants of a single common ancestor.
Name the three main groups of Excavata.
Diplomonads, Parabasalids, Euglenozoans.
What does SAR stand for?
Stramenopila, Alveolata, Rhizaria.
What process allowed Archaeplastida to obtain chloroplasts?
Primary endosymbiosis.
What theory explains how mitochondria and chloroplasts originated?
The endosymbiotic theory.
What are the five eukaryotic supergroups that include protists?(Give 1)
Excavata, SAR, Archaeplastida, Amoebozoa, and Opisthokonta.
Which parasitic diplomonad causes intestinal disease in humans?
Giardia.
What group includes diatoms and brown algae?
Stramenopiles.
Which group includes red and green algae?
Archaeplastida.
What evidence supports endosymbiosis?
Organelles have circular DNA, bacterial-type ribosomes, and reproduce by binary fission.
What are cysts in protists used for?
Dormant cells used for protection or disease transmission.
What is unique about Parabasalids like Trichomonas vaginalis?
Have undulating membranes and semifunctional mitochondria.
Which alveolate causes malaria?
Plasmodium (an Apicomplexan).
What group of protists gave rise to land plants?
Charophytes.
What is secondary endosymbiosis?
When a eukaryote engulfs another eukaryote that already has chloroplasts (e.g., brown algae).
What are the three main types of protist locomotion?
Flagella, cilia, and pseudopodia.
What structure allows Euglena to move toward light?
The stigma (eyespot).
What are foraminifera shells made of?
Calcium carbonate (CaCO₃).
What type of movement do Amoebozoa use?
Pseudopodia.
What did mitochondria and chloroplasts likely evolve from?
Engulfed aerobic bacteria and photosynthetic cyanobacteria, respectively.
Define mixotrophy.
When a protist can perform both photosynthesis and heterotrophy.
Trypanosomes, which cause diseases like sleeping sickness, belong to which group?
Kinetoplastids, within Euglenozoa.
What causes “red tides” and can produce toxins harmful to fish and humans?
Dinoflagellates.
Which protist group is most closely related to animals?
Choanoflagellates (Opisthokonta).