It includes all the unicellular eukaryotic organisms.
Most of the protists are free living and aquatic. Few are parasites.
Locomotory organs are cilia, flagella and pseudopodia.
Cell wall, if present, is made up of cellulose.
They have true nucleus and membrane bound cell organelles as they are eukaryotes.
Protists show autotrophic, holozoic, saprophytic or parasitic mode of nutrition.
They reproduce sexually (zygote formation) and asexually (binary fission). During unfavorable condition, they form cysts.
Protists are grouped into,
(i) Chrysophytes
(ii) Dinoflagellates
(iii) Euglenoids
(iv) Slime moulds
(v) Protozoans
Chrysophytes
This group includes Diatoms and Golden Brown algae (desmids).
They are aquatic, both freshwater and marine water forms.
They are microscopic and float passively in water current.
The cell wall has deposits of silicon dioxide which is indestructible. Cell wall is arranged like a soap box.
They are most important and chief producers in marine ecosystem, as most of them are photosynthetic.
When diatoms die they leave behind silica cell walls. Accumulation of these over billions of years, led to large deposits of silica in ocean called Diatomaceous earth.
Gritty diatomaceous earth soil is used in polishing and filtration of oils.
E.g. Chrysosphaerella (Desmid).
Dinoflagellates
They are unicellular, marine photosynthetic organisms.
They are biflagellate and motile, they exhibit unique spinning movement called whirling whips.
The cell wall of the dinoflagellates have stiff cellulose plates along with pectin.
They appear yellow, green, brown, blue or red depending upon pigment present in their cells.
Red dinoflagellates undergo rapid multiplication and causes red tides in oceans.
Ex: Gonyaulax, Glenodinium.
Euglenoids
They are free living fresh water forms found in stagnant water.
They lack cell wall. Instead, they have a protein rich layer called pellicle, which gives flexibility to their body.
They are biflagellate and unequal in size. Long flagella helps in locomotion.
In the presence of sunlight they are photosynthetic. When sunlight is absent they behave like heterotrophs.
They reproduce asexually by binary fission and form cysts during unfavorable condition.
E.g. Euglena.
Slime moulds
They are saprophytes. They present in both cellular and acellular form.
The body moves along with decaying twigs and leaves and engulf organic matter.
They form multi nucleated large mass of protoplasm without cell wall, forms slimy network of living matter called plasmodium.
During unfavorable condition, plasmodium differentiates and forms fruiting body sporangia, which produce spores.
E.g. Dictyostelium
Protozoans
They are heterotrophs, lives as parasites or predators.
They are the primitive animals with simple protoplasmic organization.
Locomotory organs are flagella, cilia or pseudopodia.
There are 4 major groups,
(a) Amoeboid protozoans
(b) Flagellated protozoans
(c) Ciliated protozoans
(d) Sporozoans.
(a) Amoeboid Protozoans
They are present in fresh water or marine water.
They does not have particular shape.
The locomotion and food capture is by the pseudopodia.
Some of the members are parasites in human beings and animals.
Ex: Amoeba, Radiolaria
(b) Flagellated protozoans
The members are either free living or parasites.
Locomotion is by the help of flagella.
Parasitic forms causes diseases in human beings.
E.g. Trypanosoma (causes sleeping sickness in man)
(c) Ciliated Protozoans
They are aquatic and have characteristic shape.
Locomotory structures are cilia.
They have a cavity (gullet) that opens to the outside of the cell surface.
The coordinated movement of rows of cilia causes the water laden with food to be steered into the gullet.
E.g. Paramoecium
(d) Sporozoans
They are the parasitic protozoans.
Locomotory organs are absent.
They have an infectious spore-like stage in their life cycle.
They cause diseases in human beings.
E.g. Plasmodium
Most of the protists are free living and aquatic. Few are parasites.
Locomotory organs are cilia, flagella and pseudopodia.
Cell wall, if present, is made up of cellulose.
They have true nucleus and membrane bound cell organelles as they are eukaryotes.
Protists show autotrophic, holozoic, saprophytic or parasitic mode of nutrition.
They reproduce sexually (zygote formation) and asexually (binary fission). During unfavorable condition, they form cysts.
Protists are grouped into,
(i) Chrysophytes
(ii) Dinoflagellates
(iii) Euglenoids
(iv) Slime moulds
(v) Protozoans
Chrysophytes
This group includes Diatoms and Golden Brown algae (desmids).
They are aquatic, both freshwater and marine water forms.
They are microscopic and float passively in water current.
The cell wall has deposits of silicon dioxide which is indestructible. Cell wall is arranged like a soap box.
They are most important and chief producers in marine ecosystem, as most of them are photosynthetic.
When diatoms die they leave behind silica cell walls. Accumulation of these over billions of years, led to large deposits of silica in ocean called Diatomaceous earth.
Gritty diatomaceous earth soil is used in polishing and filtration of oils.
E.g. Chrysosphaerella (Desmid).
Dinoflagellates
They are unicellular, marine photosynthetic organisms.
They are biflagellate and motile, they exhibit unique spinning movement called whirling whips.
The cell wall of the dinoflagellates have stiff cellulose plates along with pectin.
They appear yellow, green, brown, blue or red depending upon pigment present in their cells.
Red dinoflagellates undergo rapid multiplication and causes red tides in oceans.
Ex: Gonyaulax, Glenodinium.
Euglenoids
They lack cell wall. Instead, they have a protein rich layer called pellicle, which gives flexibility to their body.
They are biflagellate and unequal in size. Long flagella helps in locomotion.
In the presence of sunlight they are photosynthetic. When sunlight is absent they behave like heterotrophs.
They reproduce asexually by binary fission and form cysts during unfavorable condition.
E.g. Euglena.
Slime moulds
They are saprophytes. They present in both cellular and acellular form.
The body moves along with decaying twigs and leaves and engulf organic matter.
They form multi nucleated large mass of protoplasm without cell wall, forms slimy network of living matter called plasmodium.
During unfavorable condition, plasmodium differentiates and forms fruiting body sporangia, which produce spores.
E.g. Dictyostelium
Protozoans
They are heterotrophs, lives as parasites or predators.
They are the primitive animals with simple protoplasmic organization.
Locomotory organs are flagella, cilia or pseudopodia.
There are 4 major groups,
(a) Amoeboid protozoans
(b) Flagellated protozoans
(c) Ciliated protozoans
(d) Sporozoans.
(a) Amoeboid Protozoans
They are present in fresh water or marine water.
They does not have particular shape.
The locomotion and food capture is by the pseudopodia.
Some of the members are parasites in human beings and animals.
Ex: Amoeba, Radiolaria
(b) Flagellated protozoans
The members are either free living or parasites.
Locomotion is by the help of flagella.
Parasitic forms causes diseases in human beings.
E.g. Trypanosoma (causes sleeping sickness in man)
(c) Ciliated Protozoans
Locomotory structures are cilia.
They have a cavity (gullet) that opens to the outside of the cell surface.
The coordinated movement of rows of cilia causes the water laden with food to be steered into the gullet.
E.g. Paramoecium
(d) Sporozoans
They are the parasitic protozoans.
Locomotory organs are absent.
They have an infectious spore-like stage in their life cycle.
They cause diseases in human beings.
E.g. Plasmodium
0 Comments