Protista

Question 1

Kingdom Protista

Answer 1

Usually considered the junk drawer of classification as it contains all that don’t fit in the other five kingdoms

Question 2

Characteristics of Protists

Answer 2

→ Eukaryotic
↪ Most diverse group of all the eukaryotic kingdoms

→ Very few general characteristics can be stated without exceptions
↪ Most are single-celled, some are colonial (cells just live together but can survive on their own), some are multi-celled (celles cannot survive on their own)
↪ Some are heterotrophic, some are autotrophic
↪ Some are mobile, some are sessile (immobile)

Question 3

Three groups of Protists

Answer 3

Protozoa (animal like protists) → Heterotrophs that ingest or absorb their food
↪ Mostly Unicellular and microscopic (unlike animals)
↪ Shape varies and they don’t have a cell wall

Algae (plant like protists) → Autotrophs that can carry out photosynthesis and contain chlorophyll
↪ No leaves, stems, roots and does not contain cellulose in cell wall (unlike plants)
↪ Not a lot in common (“Algae” is not a proper classification)
↪ Refers more to all aquatic life that carry out photosynthesis

Slime and Water Moulds (fungi-like protists) → Spore producing heterotrophs
↪ Difficult to classify
↪ They can glide place to place and ingest food like protozoa
↪ They have cellulose in their cell walls like plants

Question 4

Types of Protozoa

Answer 4

Flagellates: Have one or more flagella for movement

Ciliates: Have cilia that beat in a coordinated rhythm to move the micro-organism. Also help sweep food into the ‘mouth’ (oral cavity).

Sarcodines: Use extensions of the cytoplasm called pseudopods for movement and feeding. Some are soft-bodied while other are shelled. Like the amoeba.

Sporozoans: Parasites that form spores in their life cycle. The spores attach to host species/vectors. They are non-motile and move around using host.

Question 5

Why are protozoa important?

Answer 5

→ Food source for other organisms

→ Mutualism relationships
↪ Trichonympha – makes it possible for termites to eat wood. Termites do not have the enzyme to digest wood.

Question 6

Types of Algae

Answer 6

Green Algae
→ Most likely the ancestor of plants
→ Some are flagellated
↪ Chloroplasts on flagellated green algae often have a red-pigmented eyespot that helps in swim toward well-lit areas to carry out photosynthesis

Brown Algae
→ Multicellular, photosynthetic, aquatic organisms with cell walls make of cellulose and alginic acid
→ Commonly called seaweed

Dinofagellates
→ Unicellular, photosynthetic organisms that act as an important food source since they are abundant
→ Have protective coats made of cellulose
→ All have two flagella
↪ One lies in a long groove covering the cell while the other is a long ribbon like flagella the encircles the organism

Diatoms
→ Unicellular, photosynthetic organisms that have rigid cell walls made of silica
→ Large component of plankton ( lil shrimps ) diet, base of the food chain in aquatic environments.

Euglenoids
→ Unicellular, photosynthetic organism that have a pellicle (coating of protein) instead of a cell wall.
→ Has two flagella with one being longer than the other
→ Over half are heterotrophs (originally autotroph but become heterotrophs due to low light)

Question 7

Why are algae important?

Answer 7

→ Major producers in the world’s oceans and base of the aquatic food chain
→ Produce largest portion of the planet’s oxygen via photosynthesis
→ Provides coral reef with energy via photosynthesis. ( Coralline red algae helps provide calcium to growing coral reefs )
→ Algae like help provide shelter to aquatic life

Question 8

Threats to Biodiversity

Answer 8

→ Climate change is affecting many protists, including algae.
↪ In aquatic ecosystems the temperatures of oceans and lakes are rising.
↪ The water is also becoming more acidic, which may interfere with some protists’ ability to produce their outer protective shells- they may not survive.
→ The loss of these protists may severely damage food webs that rely on the photosynthetic protists as the primary producers.
→ Warmer water temperatures may also allow the population sizes of some algae species to increase = leading to algal blooms, which can actually deplete the oxygen availability in the water as there is no sunlight for the underwater plants/protists to produce oxygen. (Eutrophication)

Question 9

Why are slime and water mould important?

Answer 9

→ Act as decomposes, recycling nutrients in an ecosystem

↪ Results in rich topsoil, providing nutrients for plants

Question 10

Applications of Protists

Answer 10

→ In medicine
→ In scientific studies
→ Commercial industries