Question

read the paragraph.
despite its name, the pacific sea horse is actually a type of fish. its horse - shaped head gives it its name. this creature lives in the pacific waters off the west coast of the americas, from peru to southern california. like many other ocean fish, sea horses face the constant challenge of losing water to their saltier environment.
when a pacific sea horse’s body loses water to its environment, which process is responsible?
○ osmosis
○ active transport
○ exocytosis
○ endocytosis

Explanation:

To determine the process responsible for the Pacific sea horse losing water to its saltier environment, we analyze each option:

• Osmosis: It is the passive movement of water across a semi - permeable membrane from an area of lower solute concentration (higher water potential) to an area of higher solute concentration (lower water potential). In the case of the Pacific sea horse, its body has a lower solute concentration (compared to the saltier ocean water). So, water moves out of the sea horse's body (where water potential is higher) into the environment (where water potential is lower) through osmosis.
• Active transport: This process requires energy (ATP) to move substances against their concentration gradient. Since water movement here is down the water potential gradient (passive), active transport is not the cause.
• Exocytosis: It is the process by which cells expel large molecules or particles (like proteins, waste) by fusing vesicles with the cell membrane. It has nothing to do with water movement due to solute concentration differences.
• Endocytosis: This is the process of a cell taking in substances (like nutrients, particles) by engulfing them. It is also not related to the passive movement of water due to osmotic gradients.

So, the process responsible for the sea horse losing water to its environment is osmosis.

Answer:

A. osmosis