Question

In Amoeba, the contractile vacuole is present
(A)Near the trailing end
(B)Near the advancing end
(C)At the middle of the body
(D)Anywhere inside the body

Answer 1

Hint: In Amoeba, the contractile vacuole is present in the posterior part of the amoeba at the end which helps in dragging the organism or moving the organism. This vacuole is filled with water.

Complete answer:
Contractile vacuole is the excretory structure in Amoeba, which is a specialized type of vacuole which helps in regulating the amount or quantity of water which should be present there in the cell. Like other vacuoles, it is also oval in shape. It is situated near the trailing end.

Additional Information: The contractile vacuole is essentially a water bubble within the endoplasm of A. proteus. Its function is to manage the water content of the cell. It's also a way of excreting its waste from the cell i.e out through the cell membrane via diffusion. Even if the contractile vacuole is absent, the amoeba may burst. As osmotic pressure is to be maintained, to manage pressure in amoeba.
Most amoebae which are present in freshwater have a contractile vacuole that expels excess water from the cell. it's seen that the
freshwater features a lower concentration of solutes like salt than the amoeba's own internal fluids
(cytosol) Without a contractile vacuole, the cell would fill with excess water and, eventually, burst, because the surrounding water is hypotonic when considered with respect to the contents of the cell, water is transferred or passed across the amoeba's cell membrane by osmosis.
So, the correct answer is ‘Near the trailing end’.

Note: Contractile Vacuole is not present in every amoeba. The contractile vacuole is absent in the case of the marine amoebae because the solute concentrations inside the cell are in balance with the concentration of the surrounding water.