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Some protozoa have complex life cycles requiring two different host species; others require only a single host to complete the life cycle. A single infective protozoan entering a susceptible host has the potential to produce an immense population.
- Robert G. Yaeger
- 1996
- 1996
- Introduction
- Anatomy
- Classification of Phylum Protozoa
- Classification Based on Mode of Existence
- Parasitic Protozoa
- Life Cycle of Free Living Protozoa
- Classification Based on Nutrition
- Microscopy
- References
Essentially, protozoa are single-celled eukaryotes.This means that they are single celled organisms that have a nuclei as well asa number of other important organelles within the cytoplasmand enclosed by amembrane. They exist as free-living organisms or as parasites. Thismakes this phylum a diverse group of unicellular organisms, varying in shape a...
Given that they are eukaryotes, protozoa arelarger cells of between 10 and 100 micrometer in diameter (compared toprokaryotes) with a more complex structure. This means that they have a cellmembrane which bounds the organelles, a DNA that is also bound by a membrane, nucleoli,ribosome, Golgi apparatus and multiple linear chromosomes with histonesam...
Because of their diversity, protozoa presentseveral problems when it comes to classification. They are considered to be under the sub-kingdom protista with more than 50,000 species being described asfree-living (these are the type that do not directly depend onothers for survival). Free-living protozoa can be found in virtually everypossible habita...
Of the existing protozoa, there are about 21,000species that occur as free-living in a variety of habitats while another 11,000 species occur as parasiticmicrobes in both vertebrate and invertebrates hosts. The free-living species can be foundin various habitats and particularly in soil and water. These types of protozoahave little impact on human ...
Parasitic protozoa are the type thatdepend on the host for survival. As such, they live inside the host and evencause health problems. The following are some of the parasitic: Sarcodina ( e.g. Entamoeba)- Entamoeba histolyticais a type of amoeba that lives in the human alimentary canal. For most part,they are harmless and feed on various bacteria a...
For this group, the life cyclelargely involves the growth and increase in size of the organism which is thenfollowed by binary fission(or other forms of asexual reproduction). For thefree-living, sexual reproduction only occurs under unfavorableconditions (unfavorable temperature, or reduced food supplies etc). However,these factors often vary from...
There are three main categories based on nutrition. These include: 1. Photo-autotrophs 2. Photo-heterotrophs 3. Chemoheterotrophs Autotrophs Autotrophs like some of the flagellatessynthesize carbohydrates from carbon dioxide and water using chlorophyll. Here,radiant energy from the sun is used. Most of the photoautotrophic flagellatesincluding memb...
As previously mentioned, protozoa are verydiverse. As such, they are distinguished from one another based on theirdifferent structural features, means of locomotion as well as the formation ofspores. Using a light microscope, it's possible to view different types ofprotozoa. Sample collection Protozoa can be obtained from almost any givenhabitat. W...
Ward's Science (2005) Working with protozoa. Johanna Laybourn-Parry (1984) A functionalbiology of free-living protozoa. Gary N. Calkins (1906) The Protozoan Life Cycle. J. P. Kreier and J. R. Baker (1987) Anatomy andphysiology of the protozoa. R. W. Hegner (1926) Homologies and AnalogiesBetween Free-Living and Parasitic Protozoa. Martinez AJ, Visve...
Most sessile protozoa are able to move around at some stage in the life cycle, such as after cell division. The term 'theront' has been used for actively motile phases, as opposed to 'trophont' or 'trophozoite' that refers to feeding stages.
Oct 1, 2024 · The life cycle of protozoa is a complex and dynamic process that ensures their survival, reproduction, and adaptability across diverse environments. Understanding these life cycles is essential for comprehending the ecological roles of protozoans and their interactions with other organisms.
Aug 3, 2023 · Most protozoa’s life cycle alternates between the vegetative stage, the trophozoite, and the dormant cyst stage. During the trophozoite stage, the parasites actively divide, forming more cells. Some protozoa develop protective structures called cysts during unfavorable conditions or environmental stress.
Aug 31, 2023 · Protozoa are unicellular eukaryotic microorganisms lacking a cell wall and belonging to the Kingdom Protista. Protozoa reproduce asexually by fission, schizogony, or budding. Some protozoa can also reproduce sexually.
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Nov 26, 2023 · Parasitic protozoa exist in two main stages: an active stage (trophozoite) during which they obtain nutrition and multiply, and a dormant stage (cyst) that can survive outside a host in the environment; some species have multiple morphological stages and complex life cycles.
