An organism under observation is found to be spindle shaped and single-celled. It has a long flagellum showing contractile locomotion in pure water. There appears a single nucleus and many chloroplasts. To which one of the following kingdoms this organism fits into ?

An organism under observation is found to be spindle shaped and single-celled. It has a long flagellum showing contractile locomotion in pure water. There appears a single nucleus and many chloroplasts. To which one of the following kingdoms this organism fits into ? Correct Answer Protista

Concept:

• R.H. Whittaker (1969) proposed a Five Kingdom Classification.
• The kingdoms defined by him were named Monera, Protista, Fungi, Plantae and Animalia.
• The main criteria for classification used by him include cell structure, body organisation, mode of nutrition, reproduction and phylogenetic relationships.

Explanation:

• The observed organism is Euglena and it is placed in the kingdom Protista.

Characters of Euglena - 

• It is typically a spindle-shaped protist.
• It is Found in stagnant freshwater.
• Euglena has a protein-rich layer ‘pellicle’ which makes the body.
• It comprises a single nucleus and many chlorophyll-containing chloroplasts.
• It has one or two flagella that show contractile locomotion.
• It shows the mixotrophic type of nutrition i.e. it performs photosynthesis in presence of sunlight but become heterotrophs if they do not get sunlight.

Additional Information

• All single-celled eukaryotes are placed under Protista. It can be broadly classified into 5 types: Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds, and Protozoans

1. Dinoflagellates: These organisms are mostly marine and photosynthetic. They appear yellow, green, brown, blue, or red depending on the main pigments present in their cells. Example: Gonyaulax
2. Euglenoid: The majority of them are freshwater organisms found in stagnant water. Instead of a cell wall, they have a protein-rich layer called pellicle which makes their body flexible. Example: Euglena
3. Slime moulds: Slime moulds are saprophytic protists. The body moves along decaying twigs and leaves engulfing organic material.
4. Protozoan: All protozoans are heterotrophs and live as predators or parasites. They are believed to be primitive relatives of animals
5. Chrysophytes:  This group includes diatoms and golden algae (desmids). They are found in freshwater as well as in marine environments. They are microscopic and float passively in water currents (plankton). Most of them are photosynthetic.