Summarise the protist ancestors with two to three characteristics/functions of each.

Protists are a diverse group of organisms, and their ancestors can be traced back to different lineages. Here are summaries of some of the main protist ancestors:

1. Archaeplastida: This group includes red algae, green algae, and land plants. They are characterized by their ability to perform photosynthesis, thanks to the presence of chloroplasts in their cells. They are believed to have originated from a heterotrophic protist that engulfed a cyanobacterium.

2. SAR Super Group: This group includes Stramenopiles (such as diatoms and brown algae), Alveolates (such as dinoflagellates and plasmodium), and Rhizarians (such as foraminiferans and radiolarians). These protists are diverse in their characteristics and functions, ranging from photosynthetic organisms to parasites.

3. Excavata: This group includes organisms like Giardia and Trypanosoma. Many of these protists are parasites and are characterized by their unique 'excavated' feeding groove.

4. Amoebozoa: This group includes amoebas and slime molds. They are characterized by their ability to change shape, thanks to the presence of flexible cellular extensions called pseudopodia.

5. Opisthokonta: This group includes choanoflagellates and the ancestors of fungi and animals. They are characterized by a single posterior flagellum and a collar of microvilli.

Each of these groups has unique characteristics and functions, reflecting the incredible diversity of protists and their ancestors.