Contractile vacuole helps in regulation of osmotic pressure. as entamoeba histolytica has no contractile vacuole, it cant regulate osmotic pressure and hence dies.

Answer:

Introduction:
Entamoeba histolytica is a parasitic amoeba that primarily infects the human intestine. It causes a disease called amoebiasis, which can lead to severe diarrhea, abdominal pain, and other complications. This parasite has specific requirements for its survival, including a suitable environment and access to nutrients and water.

The Relationship Between Entamoeba histolytica and Fresh Water:
Freshwater is not a suitable environment for the survival of Entamoeba histolytica. There are several reasons for this, and one of them is the absence of a contractile vacuole in the parasite. A contractile vacuole is a specialized organelle found in many single-celled organisms, including amoebas. Its main function is to regulate osmotic pressure within the cell by actively pumping out excess water. Without a contractile vacuole, the parasite would be unable to maintain its internal water balance in a freshwater environment.

Reasons for the Death of Entamoeba histolytica in Fresh Water:
There are a few reasons why Entamoeba histolytica would die if kept in fresh water:

1. Lack of Food: Freshwater does not provide the necessary nutrients and food sources required by Entamoeba histolytica. This parasite obtains its nutrition by ingesting bacteria, other microorganisms, and debris present in the human intestine. Without access to these food sources, the parasite would starve and eventually die.

2. Loss of Pseudopodia: Entamoeba histolytica uses pseudopodia, which are temporary extensions of its cytoplasm, for movement and phagocytosis (engulfing and ingesting food particles). In a freshwater environment, the absence of a contractile vacuole would disrupt the cytoplasmic flow necessary for the formation and retraction of pseudopodia, rendering the parasite immobile and unable to feed.

3. Imbalance in Water Regulation: Without a contractile vacuole, Entamoeba histolytica would be unable to regulate its internal water balance in a freshwater environment. The osmotic pressure inside the parasite would be higher than its surroundings, resulting in a continuous influx of water. This excessive water uptake can cause the cell to burst, leading to its death.

Conclusion:
Entamoeba histolytica, a human intestinal parasite, cannot survive in freshwater due to various reasons. The absence of a contractile vacuole in the parasite disrupts the regulation of osmotic pressure and leads to the continuous influx of water. Additionally, the lack of food sources and the inability to form pseudopodia for movement and feeding further contribute to the parasite's inability to survive in freshwater.