In some freshwater organisms there is a structure called a contractile vacuole that regulates water movement into and out of the cell. what explains the existence of the cv?
a) the cv prevents the organism from drying out.
b) the cv assists the organism in capturing prey.
c) the cv the organism move through the water.
d) the cv the organism maintain osmotic pressure.

The correct answer would be option D.

The contractile vacuole is a cell organelle which is mainly involved in the regulation of osmotic pressure.

It helps in pumping excess water out of the body.

In freshwater organisms, the inside of the cell is hypotonic as compared to water present outside the body. Consequently, the water keeps moving in the cell due to osmosis.

The contractile vacuole helps in removing this excess water out of the cell and thus, helps in regulating the osmotic pressure.

a. suckling by young

b. hypothalamus

c. dopamine

d. trh

e. anterior pituitary

f. mammary glands

g. milk production