Question

Phylum protozoa are classified on the basis of
A. Mode of reproduction
B. Locomotive organelles
C. Mode of nutrition
D. None of the above

Answer 1

Hint: Protozoa are single-celled eukaryotes which are organisms whose cells have nuclei. They commonly show characteristics associated with animals. Most of which are notably mobility and heterotrophy. They along with the plant-like algae and fungus-like water molds and slime molds are grouped in the kingdom Protista.

Complete answer:
Phylum protozoa are classified on the basis of locomotory organelles. This classification is done into four groups:-

1. Mastigophora (Zooflagellata): They locomote through flagella. They include free-living aquatics, parasites, commensals, or symbionts. They could be uninucleate or multinucleate. Their body is covered by a firm pellicle. For example- Trypanosoma, Giardia, Leishmania, etc.
2. Sporozoa: they are endoparasites which lack Locomotory organelles. Their body is covered with an elastic pellicle or cuticle. For example- Plasmodium, Monocystis, etc.
3. Sarcodina (Rhizopoda): They locomate by developers pseudopodia which are temporary protoplasmic outgrowths. These are of four types- lobopodia (broad and blunt), filopodia (slender, unsupported, independent), axopodia (slender with axial support), and reticulopodia (slender, reticulate). Pseudopodia are also used for engulfing food particles. Their body is covered with plasmalemma or a shell. For example- Amoeba, Entamoeba, etc.
4. Ciliata: They locomote by developing a number of cilia during a part or whole of the life cycle. Cilia are also used for driving food. They have definite regions for ingestion and egestion. Ciliates show defense mechanisms through minute ejectable trichocysts for defense. For example-/Paramecium, Opalina, etc.

The correct option is B- locomotory organelles.

Note: There are Seven phyla of Protozoa that are accepted in this classification-
1. Sarcomastigophora
2. Labyrinthomorpha
3. Apicomplexa
4. Microspora
5. Ascetospora
6. Myxosporea
7. Ciliophora