Protozoans: All protozoans are heterotrophs and live as predators or parasites. They are believed to be primitive relatives of animals. Protozoa are one-celled animals found worldwide in most habitats. Most species are free living, but all higher animals are infected with one or more species of protozoa. Infections range from asymptomatic to life threatening, depending on the species and strain of the parasite and the resistance of the host.
Protozoa are microscopic unicellular eukaryotes that have a relatively complex internal structure and carry out complex metabolic activities. Some protozoa have structures for propulsion or other types of movement.
On the basis of light and electron microscopic morphology, the protozoa are currently classified into six phyla. Most species causing human disease are members of the phyla Sacromastigophora and Apicomplexa.
The stages of parasitic protozoa that actively feed and multiply are frequently called trophozoites; in some protozoa, other terms are used for these stages. Cysts are stages with a protective membrane or thickened wall. Protozoan cysts that must survive outside the host usually have more resistant walls than cysts that form in tissues.
Binary fission, the most common form of reproduction, is asexual; multiple asexual division occurs in some forms. Both sexual and asexual reproduction occur in the Apicomplexa.
All parasitic protozoa require preformed organic substances—that is, nutrition is holozoic as in higher animals.
| JOIN OUR TELEGRAM CHANNELS | ||
| Biology Quiz & Notes | Physics Quiz & Notes | Chemistry Quiz & Notes |
By Team Learning Mantras
TNPSC Civil Services Exam Notification: The Tamil Nadu Public Service Commission (TNPSC) has Announced Notification…
Best Books for RRB Technician Exam: The Railway Recruitment Board conducts the RRB Technician Exams.…
RRB Technician Result: The Railway Recruitment Board announces the RRB Technician Result within a month…
RRB Technician Admit Card: The Railway Technician Admit Card will be released by the Railway…
RRB Technician Salary: The RRB Technician Grade Pay is 1900 and Basic pay is 19900+HRA…
RRB Technician Study Materials: The Railway Recruitment Board conducts the RRB Technician Exams. Government of India,…
This website uses cookies.