Question

In the five kingdom classification, chlamydomonas and chlorella have been included in
A) Protista
B) Algae
C) Plantae
D) Monera

Answer 1

Hint: In 1969, R.H. Whittaker proposed the five-kingdom classification. Certain characters like mode of nutrition, thallus organization, cell structure, phylogenetic relationships and reproduction are considered while classification. Chlamydomonas, Chlorella, Paramoecium and Amoeba were earlier placed with animals and plants till the five kingdom classification.

Complete answer:
Based on the two kingdom classification of Carolus Linnaeus, putting all the organisms in either plant or animal kingdom was insufficient because there were a lot of organisms which could not be classified as either plants or animals. The five-kingdom classification of organisms included the kingdoms: Monera, Protista, Fungi, Plantae and Animalia.

Since chlorella and chlamydomonas have the features of Protista, they are classified under this Kingdom. In earlier classification schemes Chlamydomonas was placed under plantae in sub category algae along with the chlorella as they cell wall in both. But Whittaker’s five kingdom classification hosted other features apart from gross morphology like phylogeny and cell structure. Hence, chlorella and chlamydomonas were placed in a kingdom especially meant for unicellular eukaryotes Protists. They were earlier classified as Algae within Plants and both of them have cell walls.

Protista has the following important features:
• They are eukaryotic and unicellular organisms.
• Some of them have flagella or cilia for mobility.
• Sexual reproduction is by a process of zygote formation and cell fusion.

Hence, the correct answer is option (A).

Note: Kingdom Protista is again categorized into sub groups:
• Chrysophytes: The diatoms and the golden algae (desmids) fall under this group. They are found in freshwater and marine habitats.
• Dinoflagellates: They are usually marine and photosynthetic. Their color is dependent on the key pigments in their cells; they appear blue, brown, red, green or yellow.
• Euglenoids: Most of the Euglenoids live in freshwater habitation in motionless water. Instead of the cell wall, there is a protein-rich layer called pellicle.
• Slime Moulds: They are saprophytic. The body moves along putrefying twigs and leaves and nourishes itself on organic materials. They form an accumulation under favorable surroundings and are called Plasmodial slime moulds.
• Protozoans: These are heterotrophs and they survive either as predators or parasites.