Protozoa - Practice Questions & MCQ

• Protozoa are eukaryotic, unicellular animal-like organisms.

• Mode of nutrition is heterotrophic. They can be saprotrophic or parasitic.

• On the basis of the locomotory organelle, protozoans are divided into four groups i.e. Flagellated protozoa, amoeboid protozoa, ciliated protozoa and sporozoa.

• The branch of biology dealing with the study of protozoa is called Protozoology.

 Flagellated protozoa:

• These protozoans are flagellated i.e. they have flagella for locomotion.

• They can be free-living, parasitic, aquatic etc.

•  Mode of nutrition is holozoic, saprobic or parasitic.

• Body possesses a proteinaceous layer pellicle.

• Reproduction is generally by binary fission.

• Many organisms falling in this group cause diseases in humans and other animals.

 Amoeboid Protozoa:

• These protozoa can temporarily develop pseudopodia which are cytoplasmic outgrowths.

•  Pseudopodia are used for feeding, locomotion etc.

• The body is covered with the plasma membrane.

• Mode of nutrition is holozoic.

• Asexual reproduction is by fission, budding and spores.

• Sexual reproduction is also seen.

• Examples include Amoeba proteus, Pelomyxa, Entamoeba histolytica etc.

Ciliated Protozoa

• These are protozoa with cilia used for locomotion and driving food

• Ciliates are generally free-living in fresh and marine water habitats.

• The body is covered by a pellicle which is proteinaceous in nature.

• Mode of nutrition is holozoic.

• Nuclear dimorphism is seen. Macronucleus and micronucleus are found. Macronucleus is vegetative and micronucleus is reproductive.

• Ciliates show trichocysts also. These are defensive structures.

• Asexual and sexual reproduction both are seen.

• Examples include Paramoecium, Vorticella, Opalina, Balantidium.

Sporozoa:

• In these protists, locomotory organelles are absent.

• All sporozoans are generally endoparasites.

• Mode of nutrition is parasitic.

• The body is generally covered with pellicle or cuticle.

• Asexual reproduction is through multiple fission.

• Examples include Plasmodium, Monocystis, Eimeria.

• Monocystis live as endoparasite in epithelial cells and seminal vesicle of earthworm.

• Eimeria is an intracellular parasite in the ileum of birds.

• Plasmodium is the most deadly member of this group. It causes Malaria in humans.