Question

Major function of contractile vacuole of Amoeba and others is
A) Excretion
B) Circulation
C) Osmoregulation
D) All of the above

Answer 1

It is a unicellular organism which has the ability to alter its shape, primarily by extending and retracting their pseudopodia. Pseudopodia is derived from two words i.e. pseudo= false and poda =foot; means one having false foot.

Complete answer:
Amoeba is the unicellular organism that belongs to the class Sarcodina that possesses pseudopodia or move by protoplasmic flow. It can be of variable size and their size varies from 3 micrometers to 20 cm in diameter. It is having a specialized movement called an amoeboid movement. It is having contractile vacuole that is responsible for performing excretion, osmoregulation, circulation etc.

Additional information: The contractile vacuole is the sub cell organelle that is mostly found in unicellular protists and in some unicellular algae. It was previously called as pulsatile or pulsating vacuole having the main function of osmoregulation. Some Amoeba is pathogenic and causes disease both in animals as well as in humans too. Amoebic dysentery is the most pathogenic form of diarrhea which is caused by Entamoeba histolytica ; Naegleria fowleri is called brain eating amoeba. Amoeba can be marine or freshwater. In freshwater amoeba, the contractile vacuole is necessary because freshwater has a lower concentration of solutes than the amoeba’s own internal fluids. So if the contractile vacuole is absent in freshwater amoeba then the cell will fill with excess of water and eventually burst out.

The correct option is D i.e. all of the above.

Note: Marine amoeba does not usually possess a contractile vacuole due to the concentration of solutes within the cell are in balance with the tonicity of the surrounding water. Thus they do not need osmoregulation.