Kingdom Protista

Protists are the first eukaryotes to evolve about 1000 million years back. Protists are all unicellular and colonial eukaryotes except green and red algae. They are broadly divided into- photosynthetic, slime moulds and protozoans.

Leeuwenhoek was the first to see and sketch protozoan’s protists including Vorticella and Giardia.

Characteristics of protists are:

*They are solitary unicellular, colonial unicellular, eukaryotic organism.

*They are mostly aquatic organism.

*A well defined nucleus (uninucleate, binucleate or multinucleated). Genetic material is RNA, enclosed by nuclear envelope, complexed with protein with distinct chromosome.

*Almost 95% of the protists are consisting of phytoplankton and 80% of the total photosynthesis is carried out by photosynthetic protists.

*If cell wall is, it is made up of cellulose.

* Cytoplasm contains ribosomes, a variety of organelles such as mitochondria, plastid, lysosome, cytoskeleton, endoplasmic reticulum and Golgibodies. Some contains centriole and ribosomes are 80S and 70S.


*Cytoplasm is always in motion which is called cytoplasmic streaming or cyclosis.

*Locomotory organs are flagella, cilia, pseudopodia contractions, mucilage and extrusion.

*Food reserve is starch, glycogen, paramylon, chrysolaminarin and fat.

*Asexual reproduction is quite common and occurs through budding, binary fission, multiple fission, plasmotomy, sporulation, Cyst formation etc.

*Sexual reproduction occurs with the help of nonjacketed gametangia by meiosis and karyogamy.

*Three types of life cycle occur in protists are- plant, animal and fungal.

*Protistans serve as the linkage between monerans and rest of the kingdom.

*Mitotic apparatus is formed during cell division.

*No embryo is formed.

Protists can be divided into-

1. Euglenophyta - This include Euglinoids organism. This phylum category includes flagellate protists of freshwater, damp soils. Previously they were included in phytomastigophora by zoologist. They have tinsel and tactellum type of flagellum with the roots developing from an invagination and an eye spot nearby. E.g. Euglena, Paranema, Phacus, Rhabdomonas.

2. Xanophyta-This phylum includes yellow green algae.

3. Chrysophyta- They are also called Golden algae. This phylum includes Chrysophyceae and Bacillariophycea.

4. They are also called Dinophyceae (dinoflagellate), Cryptomonads. They include golden brown photosynthetic protists and have two flagella. E.g. Noctiluca, Gonyaulax, Gymnodinium, Ceratium.

5. Hypochytridiomycota- They includes Hyphochytrids. Included in slime moulds.

6.Plasmodiophoromycota - The phylum includes plasmodiophores. They are also included in slime moulds.

7. Sporozoa- The phylum includes sporozoans. Malarial parasites Plasmodium are example of sporozoans.

8. Cnidosporidia- This group of protozoans are able to form spore that covered by wall.This include cnidosporidia-. E.g. Myxosporidia, Microsporidia.

9. Zoomastigina- This phylum contains zooflagellates means this protistans protozoans contain flagella as their locomotory organ. It is then categorize according to number of flagella.E. g Trichomonas, Giardia, Lophomonas.

10. Sarcodina- organismsof sarcodina contains pseudopodia. According to presence of pseudopodia it can be divided into different category. E.g. amoebids, heliozoans, foraminiferans, radiolarians.

11. Ciliophora - This phylum includes cilia as their locomotory organs. E.g. Vorticella, Paramecium, Balantidium.


Short Questions and answers on Kingdom Protista:

1. What is capillitium?

Sterile threads in sporangia of acellular slime moulds for dispersal of spores.


2. What is pyrenoids?

In euglinoids, chloroplast contains a proteinaceous body called pyrenoids.

Which is called consumer decomposer protists?

Slime moulds due to feeding on microorganisms and decaying organic matter through ingestion.


3. What is Hydramoeba?

Ectoparasitic protozoans protists feeding on epidermal cells of Hydra is called Hydramoeba.







From Kingdom Protista to HOME PAGE

New! Comments

Have your say about what you just read! Leave me a comment in the box below.


Recent Articles

  1. Eleventh Grade | Eleventh Grade Science | Eleventh Grade Math

    Jun 27, 25 12:26 AM

    Eleventh grade biology has been designed in accordance with the recommended topics. We will cover all the topics in biology very exciting and interesting way.

    Read More

  2. Explain Digestion of Food | Salivary Glands | Oesophagus | Stomach

    Jun 27, 25 12:20 AM

    Human Digestive System
    Before the digestion is start by the different enzymes secreted from the different digestive glands food must be turned and chut or mixed with saliva inside the mouth.

    Read More

  3. Explain Human Digestive System | Mouth | Tongue | Pharynx | Teeth

    Jun 21, 25 01:15 PM

    Tongue
    Digestive system is a system of alimentary canal and digestive glands. Alimentary canal- alimentary canal is a tube of variable diameter having muscular wall and glandular epithelial tissues which sta…

    Read More

  4. Vernalisation in Plants | Definition | Mechanism | Devernalization |

    Jun 18, 25 01:34 PM

    Photoperiod and Vernalisation
    Definition of vernalisation- The change of flowering habit due to the low temperature treatment is known as vernalisation. This is a physiological process which was denoted by Clipart in 1857 invite b…

    Read More

  5. The Food We Eat | Food we Get from Plants and Animals | Carbohydrates

    Jun 15, 25 03:20 PM

    Food We Eat
    What are the food that we should eat? Find out the names of ten food items in the word maze. Write the names in the correct column of the table given below. Food we get from plants Food we get from an…

    Read More