1 of 6

1. An unicellular eukaryotes, irrespective of their mode od nutrition, are included in the kingdom of Protista in Whittaker’s system. The term protista was coined by Ernst Haeckel. This Kingdom form a link between kingdom Monera on one hand and other three kingdoms i.e., Plantae, Fungi, and Animalia on the other hands. Protistans are ancestors of all multicellular eukarotes (plants, fungi and animals ).

KINGDOM PROTISTA

2 of 6

PROTISTA -KINGDOM

3. Protozoans

e.g. Zooflagellates

Sarcodines

Sporozoans

Ciliates

  1. Autotrophic

Or

Photosynthetic Organism

  1. E.g. Dinoflagellates
  2. Diatoms
  3. Euglenoids
  1. Consumer- Decomposer organism.

E.g.Cellular slime moulds

Acellular slime moulds

3 of 6

GENERAL CHARACTERISTIS OF PROTISTA

  1. Unicellular, eukaryotic organism, Some are colonial without much cellular differentiation . Organization at tissue level is absent.
  2. Mostly aquatic organism.
  3. Reproduction occurs by asexual and sexual means.
  4. Life cycle is of two types-(i) Showing zygotic meiosis (ii) ) Showing gametic meiosis.
  5. These are decomposers, photosynthetic parasites, Parasitic protists may cause diseases like dysentery, malaria, sleeping sickness, etc.

4 of 6

Photosysthetic Protists-Diatoms : Diatoms are golden brown photosysthetic protists and are called Chrysophytes (including both diatoms and desminds). They are aquatic and terrestrial.Some are marine. They support much of marine life Their important charactors are:

1.They are basically unicellular, but may formpseudofilament and colonies, lacking flagella except in the reproductive stage. They may be free floating (phytoplanktonic), remaining afloa on surface of water due to presence of light weight lipids.

2.Mode of nutrition is holophytic (photo autotrophic), photosysthetic pigments are chlorophyll a, chlorophyll c, β-carotene, and special carotenoids containing fucoxanthin; xanthophylls like diatoxanthin, diadinoxanthin.

3. The reverse food is oil and a polysaccharide called leucosin( chrysolaminarin), volutin,granulesare also present.

4.They are responsible for almost 50% of the total organic matter synthesized in the biosphere.

5. Movement occurs by mucilage propulsion.

6.They mainly undergo asexual reproduction, The common mode of asexual reproduction is binary fission.

7.During binary fission, one half of the cell wall is retained by each of the daughter cell formed. The other half of the cell wall is secreted afresh.

8. Resting spores are called statospores (centric diatoms)

9. They reproduce sexually as well , Sexual reproduction varies from isogamy to oogamy. It involves gametic meiosis as diatoms are generally diploid (diplontic life cycle).

​

​

​

5 of 6

.Dinoflagelates : Dinoflagelates are golden brown photosynthetic protists, belonging to class Dinophyceae (Pyrrophyta). They are mainly marine, though few are fresh water forms. They may appear red, yellow green brown or blue depending upon the main pigment present in cell.��General character of dinoflagellates are as follows :�1. Unicellular, motile, biflagellate, golden brown photosynthetic protists (some are non motile, amoeboid, palmelloid or filamentous).�2. They are mostly marine, some are found in fresh water�3. Most of the species have brown, green or yellow chromatophores with chlorophyll a,c,β-carotene and α- carotene, xanthophyll (e.g.Peridinin). Plastids are generally suoounded by 3- membrane envelope and contain 3-thylakoidlamellae. They are autotrophic or photosynthetic (Ceratium)a few are saprobic or parasitic.�4.Reserve food is carbohydrate and oils.�5.Nucleus is relatively larger in size, has condensed chromosomes even in interphase, chromosomesdo not have histone. Nuclear envelope and nucleolus remain present even during cell division . This organisation is called Mesokaryon.�6. Reproduction is commonly asexual and occurs through cell division.�7. Isogamous and anisogamous sexual reproduction is reportes from some dinoflagellates e.g. Ceratium.�8. Life cycle involves zygotic meiosis ( Cetatium, Gymnodinium.Gametic meiosis ocurs in Noctiluca.

6 of 6

Euglenoid ( Euglena-like) : It is a group of chlorophyll ous and non chlorophyllous flagellate protists. Largest genera being Euglena amongst them.�General character of euglenoid are as follows :�1. Euglenoids are unicellular, flagellate protists found in water or damp soil, Majority of them are fresh water organism found in stagnant water.

2.Nutrition of Euglena viridisis photoauitotrophic. However, it is capable of getting nourishment from dead and decaying organic matter in the sustrate of secreting digestive enzymes (saprophytic nutrition )in the absence of light.

This dual mode of nutrition is termed as Mixotrphic. Holozoic nutrition is absent in Euglena. Some forms are holozoic (Paranema) or saprobic (Rhabdomonas)

3.Photosynthetic pigments are chlorophyll a, chlorophyll b, xanthophyll and β-carotene.

4.Reserve food material is Paramylon , stored in cytoplasm in the form of paramylum granules. They are chemically β-1, 3- glucans.

5. Under favourable conditions, they are mainly reproduce by longitudinal binary fission . During un favourable conditions, palmella stageand cysts are formed for perennation. Sexual reproduction is not known to occur in euglenoids, e.g. Euglena and Paranema.