Some protists, like the paramecium pictured, live in freshwater. paramecium have contractile vacuoles, which act to pump water out of the cell. why? a. there is a lower solute concentration inside so water is moving into the cell constantly b. there is a higher solute concentration inside so water is moving into the cell constantly c. there is a lower solute concentration inside so water is moving out of the cell constantly d. there is a higher solute concentration inside so water is moving out of the cell constantly

B.) The extra amount of water can be accumulated at the contractile vacuole and then be withdrawn out. Paramecium lives in freshwater, where the water exhibits lower solute concentration in comparison to the cytoplasm within the cell. Therefore, due to osmosis, the water will flow within the cell. The frequency and rhythm of the contraction rely on the surrounding and also on the number of contractile vacuoles present. The contractile vacuole functions to pump out an extra amount of water from the cell.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.