Biology Protista and Chrysophytes

Study Notes

Protista

A diverse kingdom of single-celled eukaryotes
Forms a link between plants, animals, and fungi
Primarily aquatic organisms
Possesses a well-defined nucleus and membrane-bound organelles
Some have flagella or cilia
Reproduce asexually and sexually through cell fusion and zygote formation
Nutrition varies: parasitic, ingestive, photosynthetic, saprophytic, mixotrophic
Includes photosynthetic phytoplankton, non-photosynthetic zooplankton, and disease-causing parasites
Food reserves: starch, glycogen, paramylon, chrysolaminarin, and fat

Chrysophytes

Includes diatoms and golden algae (desmids)
Found in freshwater and marine environments
Microscopic and float passively in water currents (plankton)
Majority are photosynthetic
Diatoms are primary producers in oceans
Diatom cell walls consist of two overlapping shells, fitting like a soap box
Walls are made of silica, making them indestructible
Diatom shells accumulate at the bottom of water reservoirs, forming diatomaceous earth
Diatomaceous earth is used in polishing, filtration of oils and syrups

Dinoflagellates

Primarily marine and photosynthetic
Appear yellow, green, brown, blue, or red due to varying pigment proportions
Cell wall has stiff cellulose plates on the outer surface
Most have two flagella: one longitudinal and the other transverse
Red dinoflagellates, like Gonyaulax, multiply rapidly, causing "red tides"
Toxins released by red tides can kill marine animals, like fish
Exhibit bioluminescence due to photogenic granules in cytoplasm
Some species are consumed by mussels
Also known as "night light"

Euglenoids

Freshwater organisms found in stagnant water
Have a protein-rich layer called pellicle instead of a cell wall, allowing flexibility
Possess two flagella: one short and one long
Photosynthetic in sunlight
Behave like heterotrophs in the absence of sunlight, preying on smaller organisms
Pigments similar to those in higher plants
Example: Euglena

Slime Moulds

Saprophytic protists, also called "fungus animals"
Move along decaying twigs and leaves, engulfing organic matter
Form an aggregation called plasmodium under suitable conditions
Plasmodium can grow and spread over large areas
During unfavorable conditions, the plasmodium differentiates and forms fruiting bodies
Fruiting bodies bear spores at their tips
Spores have true walls and are highly resistant, surviving for years
Spores are dispersed by air currents
Example: Physarum

Description

Explore the fascinating kingdom of Protista, focusing on its diverse single-celled eukaryotes and their various nutritional strategies. Delve into the specific group of chrysophytes, including diatoms and golden algae, and understand their ecological roles in aquatic environments. This quiz covers their characteristics, reproduction methods, and significance in the ecosystem.