Bio Exam 3 - Protists

How old are the earliest protist fossils?

About 2.1 billion years old.

What was the old kingdom name used for protists?

Protista.

Why is the protist group considered heterogeneous?

Because it includes a very diverse set of organisms with different characteristics.

What cellular structures do protists have that prokaryotes lack?

Membrane-enclosed nucleus, organelles, mitochondria, cytoskeleton, cytoplasm.

About how many protist species exist?

Over 100,000 species.

What is the main theory explaining the origin of protists and other eukaryotes?

Serial Endosymbiosis Theory.

Why are protists difficult to classify?

Their extreme diversity in form, nutrition, and reproduction.

Are most protists aerobic or anaerobic?

Most are aerobic (have mitochondria).

What types of heterotrophs exist in protists?

Many protists are heterotrophic (ingest or absorb food).

What protists are photoautotrophs?

Those with chloroplasts (e.g., Spirogyra).

What is a mixotroph?

An organism that can switch between photosynthesis and heterotrophy

What is an example of a mixotrophic protist?

Euglena.

How does Euglena behave with and without light?

With light → autotroph,
Without light → heterotroph.

What are the main functional groups protists are classified into?

• Protozoa → ingestive, animal-like

• Absorptive protists → fungus-like

  • Algae → photosynthetic, plant-like

What are the main methods of movement in protists?

Flagella, cilia, pseudopodia.

How do protists reproduce?

• Some asexually,

• Some sexually,

• Some both.

Where are protists commonly found?

Aquatic and moist terrestrial habitats.

What does planktonic mean?

Living in the water column, drifting with currents.

What are phytoplankton?

Photosynthetic plankton (include algae and some cyanobacteria).

What type of organisms can be part of phytoplankton?

Cyanobacteria (even though they are prokaryotes).

What are zooplankton?

Animal-like plankton, often heterotrophic protists.

What types of symbiosis do protists participate in?

Mutualism, commensalism, and parasitism

Are many protists symbionts?

Yes, many protists live as symbionts inside or with other organisms.

Why are protists important in medical biology?

Some are major animal pathogens.

giardia

• aquatic 

• 2 nuclei

• multiple flagella

• no mitochondria

• infects human intestines 

trichomonas vaginalis

• in body fluids

• various flagella, 1 nucleus, undulating membrane

• human female’s vagina/cervix

• pain, itching, redness, green discharge

• male urethra

• asymptomatic

• STD

trypanosoma

• single large mitochondrion

• pathogenic

  • African sleeping sickness

  • vector, tse-tse fly

  • chagas’ disease

euglena 

• aquatic

• free living 

• photosynthetic 

dinofiagellates

• flagella in grooves 

• phytoplankton 

• explosive population growth (blooms)

  • cause red tides

plasamodium (malaria)

• mosquito vector

• parasites

• complex life cycle

• in tropical regions 

• modern drugs kill the parasites 

paramecium

• free living

• aquatic 

• complex nuclei 

  • sexual reproduction

diatoms

• photosynthetic 

• silica cases

• freshwater and marine 

brown algae

• giant brown algae

  • kelps, forests in deep water, 60m long

• photosynthesis

• multicellular

• marine

• float

water molds 

• fungus-like

• very important ecologically 

• many parasitic 

• sexual and asexual cycles 

forominifera

• multi-chambered porous shells

• calcium carbonate

radiolarians

• delicate symmetrical shells

• silica

red algae 

• marine 

• often multicellular 

• lack flagella 

• red pigment 

green algae

• ancestors of modern plants

• extremely important ecologically

• 10,000 sp

• chloroplasts

What is an example of a protist that reproduces sexually and asexually?

Chlamydomonas.

Why are green algae ecologically important?

They play major roles in ecosystems, including forming key symbiotic relationships.

What is a lichen?

A mutualistic, complex organism made of green algae (or cyanobacteria) and a fungus.

What type of relationship occurs in lichens?

Mutualism—both partners benefit.