Question

In order to survive in its environment, a single-celled organism uses a

contractile vacuole to remove excess water that diffuses into its cell. Another
species, a hydra, also excretes excess water. Both processes involve the use of
energy. Which type of transport would be used by these organism?

A) Passive transport.
B) Active transport.
C) Facilitated diffusion.
D) Osmosis.

Answer 1

Organisms like single-celled protists and hydras use active transport to remove excess water from their cells via a contractile vacuole to maintain osmotic balance in hypotonic environments.

Step-by-step explanation:

The organisms mentioned, such as single-celled protists and the hydra, use active transport mechanisms to remove excess water from their cells. This process is energy-intensive and is carried out by specialized structures like the contractile vacuole. The vacuole collects excess water and actively transports it out of the cell to maintain osmotic balance. This mechanism is essential because in hypotonic environments, where the solute concentration outside the cell is lower than inside, water tends to move into the cell by osmosis, risking cell swelling and burst. To prevent this, the organisms actively pump out the excess water their bodies cannot accommodate, ensuring their survival.