Kingdom Protista MCQ - Practice Questions with Answers

• These protists are autotrophic i.e. they produce their own food by the process of photosynthesis
• They possess chlorophyll and chloroplasts.
• They form the major portion of phytoplankton.
• These include dinoflagellates, chrysophytes and euglenoids.

Dinoflagellates
 

• Mostly marine, some are freshwater forms.
• Dinoflagellates are unicellular, motile and flagellated i.e. they contain two flagella for movement.
• The cells are covered by a thick plate of cellulose called theca.
• The theca contains two grooves, longitudinal groove or sulcus and circular groove called annulus or girdle.
• There are two flagella i.e. longitudinal flagella- narrow, smooth, lies in the sulcus and transverse flagella- ribbon-like, lies in an annulus
• The two flagella are responsible for spinning movement.
• The nucleus is large and called mesokaryon
• Pigments chlorophyll a and chlorophyll care present in dinoflagellates.
• Reserve food material is starch and oil.
• Examples include Glenodinium, Peridinium, Gymnodinium, Ceratium, Noctiluca.

 Economic importance of Dinoflagellates

• Gymnodinium and Gonyaulax make the water look red causing red tides.
• Gonyaulax catenella produces a neurotoxin, saxitoxin, which can cause causing paralytic shellfish poisoning (PSP) in the vertebrates when shellfish infected by saxitoxin is consumed by vertebrates.
• Noctiluca shows bioluminescence i.e. they emit light.  

 Chrysophytes

• Chrysophytes include diatoms and desmids.
• Diatoms are mostly found in aquatic and moist terrestrial habitats as free-floating forms.
• The body of diatoms is covered by a transparent siliceous shell called frustule.
• The frustule is composed of two valves which fit together like a soapbox. These two valves are epitheca and hypotheca.
• Diatoms are microscopic, eukaryotic and unicellular. They can be found in colonies also.
• Most diatoms are aflagellate except in their reproductive stage.
• Diatoms are of two types:
• Pennate: Bilateral symmetry e.g. Navicula
• Centric: Radial symmetry e.g. Melosira
• Diatom cell possesses a large nucleus suspended in a central vacuole.
• Photosynthetic pigments like chlorophyll a, chlorophyll c and fucoxanthin (brown) are present.
• Oils and leucosin are reserve food material.
• Reproduction is by binary fission. Sexual reproduction is also seen.
• Examples include Triceratium, Cymbella, Amphipleura
• Diatoms are good pollution indicators
• The siliceous frustule of diatoms can pile up at the bottom of the water and form diatomaceous earth or diatomite. This diatomite can be used in filtration of sugar,  alcohol, oil, syrups and antibiotics etc
• Desmids are unicellular green algae

Euglenoids

• Euglenoids include Euglena like flagella bearing organisms.
• These are found in freshwater habitats and damp, moist soil.
• Mode of nutrition is mixotrophic i.e. both autotrophic and heterotrophic (saprobic or holozoic). Autotrophic forms can turn heterotrophic in dark conditions.
• Euglenoids are unicellular, flagellates .
• Cell lacks a cellulosic cell wall instead of a proteinaceous, thin and flexible layer called pellicle is present. It allows changes in shape.
• Euglenoids possess two flagella one is long the other is short. Flagella bears hairs.
• A red pigment called astaxanthin is present in eyespot.
• Pigments like chlorophyll a, b are present.
• Reserve food material is paramylon
• Reproduction is by longitudinal binary fission
• Examples include Euglena, Phacus Peranema