What is useful and harmful effects of protozoa and viruses??
Answers
Answer:
The 5 harmful diseases caused by protozoans in humans are:
1. Amoebiasis - is caused by Entamoeba histolytica and can lead to ulcers in the colon.
2. Diarrhoea - is caused by Giardia lamblia and leads to loose bowels.
3. Trypanosomiasis - is caused by the Trypanosoma species which are flagellate parasites of blood plasma and leads to sleeping sickness.
4. Leishmaniasis - is caused by the species of Leishmania and leads to skin sores and spleen enlargement.
5. Malaria - is caused by four different species of Plasmodium and leads to malaria.
Explanation:
Useful protozoans:
1. Protozoans serve as food for many small aquatic organisms. Zooplankton are tiny protozoans which live in the sea. They form the principal diet of blue whales, who gulp them in with sea water.
2. They are the ultimate decomposers in nature, as they feed on bacteria and fungi, which decompose dead organic matter. They are, thus, useful in the treatment of sewage.
3. Some protozoans live in the body of other organisms and help them. Termites, for example, have protozoans living in their body. The protozoans digest the cellulose in the wood eaten by termites and convert it into carbohydrates that the termites can use.
Harmful protozoans:
Some protozoans cause diseases. The protozoan Endamoeba histolytica causes amoebiasis (amoebic dysentery) in human beings, Giardia causes giardiasis (dysentery), while Plasmodium causes malaria. trypanosome, a parasitic protozoan which lives in the bloodstream of human beings, cattle and other animals, causes a dangerous disease called sleeping sickness.