Q.36 Protozoa are
(A) unicellular (B) multicellular (C) eukaryotic (D) prokaryotic
Protozoa are unicellular eukaryotic microorganisms belonging to the Kingdom Protista. The correct answer to the multiple-choice question is (A) unicellular, as this is their defining structural characteristic. They exhibit complex life processes within a single cell, distinguishing them from multicellular organisms.
Option Analysis
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(A) Unicellular: Protozoa consist of a single cell that performs all vital functions like locomotion, feeding, and reproduction, making this the precise and primary descriptor.
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(B) Multicellular: Incorrect, as protozoa lack multiple cells organized into tissues; they are strictly single-celled, unlike animals or plants.
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(C) Eukaryotic: True but incomplete; protozoa have membrane-bound nuclei and organelles, yet the question targets their cellular organization, not domain.
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(D) Prokaryotic: False; prokaryotes like bacteria lack nuclei, while protozoa possess true nuclei and complex structures.
Protozoa are unicellular microorganisms that play key roles in ecosystems and human health. Understanding why protozoa are unicellular helps in mastering biology concepts for exams like CSIR NET.
Key Characteristics
Protozoa exhibit heterotrophic nutrition, motility via cilia, flagella, or pseudopodia, and asexual reproduction like binary fission. They thrive in aquatic environments as free-living or parasitic forms. Unlike multicellular organisms, their single cell handles all life processes efficiently.
Classification Overview
Traditionally divided into four groups: Sarcodina (amoeboids), Mastigophora (flagellates), Ciliophora (ciliates), and Sporozoa (parasites). Modern taxonomy places them in superkingdom Protista as polyphyletic eukaryotes. Examples include Amoeba (unicellular, shapeshifting) and Plasmodium (causes malaria).
Exam Relevance
For CSIR NET, focus on protozoa being unicellular distinguishes them from prokaryotic bacteria or multicellular fungi. Practice MCQs reinforces this: protozoa are not prokaryotic due to nuclear membranes.
