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Questions and Answers
Match the following terms with their definitions:
Trophozoite = A cell with a protective wall Cyst = The stage of a protozoan during feeding and growth Encystment = The process of a trophozoite becoming a cyst Schizogony = The process of a cell dividing into many smaller cells
Match the following types of plankton with their characteristics:
Phytoplankton = Photosynthetic Zooplankton = Motile and nonphotosynthetic
Match the following terms with their descriptions:
Merozoites = The products of asexual reproduction in protozoans Schizonts = Structures that store the products of schizogony Trophozoites = The products of sexual reproduction in protozoans Cysts = The stage of a protozoan during feeding and growth
Match the following types of reproduction with their characteristics:
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Match the following terms with their descriptions:
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Match the following structures with their functions in protozoans:
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Match the following types of protozoans with their modes of nutrition:
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Match the following organelles with their functions in protozoans:
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Match the following processes with their descriptions in protozoans:
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Match the following types of locomotion with their descriptions in protozoans:
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Study Notes
Protists
- A diverse group of microscopic eukaryotic organisms inhabiting aquatic and terrestrial habitats.
- Can be free-living or parasitic, causing illness in hosts.
Life Cycle
- Trophozoites: feed on small particulate food sources like bacteria during the feeding and growth part of their life cycle.
- Encystment: process by which a trophozoite becomes a cyst with a protective wall when environmental conditions are harsh.
- Excystment: process by which cysts become active again when conditions become more favorable.
Reproduction
- Asexual reproduction: occurs by binary fission, budding, or schizogony.
- Schizogony: nucleus divides multiple times before the cell divides into many smaller cells, producing merozoites stored in schizonts.
- Sexual reproduction: increases genetic diversity and can lead to complex life cycles.
- Protozoans can produce haploid gametes that fuse through syngamy or exchange genetic material by conjugation.
- Conjugation: a true form of eukaryotic sexual reproduction between two cells of different mating types.
Morphology
- Plasma membrane (plasmalemma): present in all protozoans.
- Pellicle: a structure formed by bands of protein just inside the membrane, adding rigidity.
- Cytoplasm layers: ectoplasm (outer gel layer with microfilaments of actin) and endoplasm (sol region of cytoplasm).
Feeding
- Protozoans are heterotrophic.
- Cytostome: specialized structure for taking in food through phagocytosis.
- Cytoproct: specialized structure for the exocytosis of wastes.
- Oral grooves: lined with hair-like cilia to sweep in food particles.
Locomotion
- Whip-like flagella or hair-like cilia made of microtubules: used for locomotion.
- Pseudopodia: cytoplasmic extensions used to attach the cell to a surface and move forward.
Other Features
- Contractile vacuoles: organelles used for osmotic regulation (salt and water balance).
- Mitochondria: may be absent in parasites or altered to kinetoplastids (modified mitochondria) or hydrogenosomes.
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Description
Test your knowledge of protists, a group of eukaryotic organisms that inhabit various environments, and their life cycles, including free-living and parasitic forms. Learn about the different types of plankton and their characteristics.
