Which of the following organisms would lose the most water by osmosis across its gills? a. marine bony fish b. shark c. freshwater fish d. freshwater invertebrate

Verified step by step guidance

1. Step 1: Understand the concept of osmosis. Osmosis is the movement of water molecules from an area of high concentration to an area of low concentration through a semi-permeable membrane.
2. Step 2: Understand the concept of osmoregulation in aquatic organisms. Aquatic organisms have to maintain a balance of water and salts in their bodies. This is achieved through osmoregulation, which is the process of maintaining salt and water balance (osmotic balance) across membranes within the body's fluids.
3. Step 3: Consider the environment of each organism. Marine bony fish live in saltwater, which has a higher concentration of salts than their body fluids. Sharks, also marine organisms, have a salt concentration in their bodies similar to that of seawater. Freshwater fish and invertebrates live in an environment with a lower concentration of salts than their body fluids.
4. Step 4: Apply the concept of osmosis to each organism. In marine bony fish, water tends to move out of their bodies into the surrounding seawater, causing them to lose water. Sharks, having a similar salt concentration to seawater, do not lose as much water. Freshwater fish and invertebrates, on the other hand, tend to gain water from their environment.
5. Step 5: From the above analysis, the marine bony fish would lose the most water by osmosis across its gills because it lives in an environment with a higher concentration of salts than its body fluids.

Key Concepts

Osmosis

Osmosis is the movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. This process is crucial for maintaining cellular homeostasis and is particularly relevant in aquatic organisms, where the surrounding water's salinity can significantly affect water balance.

Salinity and Osmoregulation

Salinity refers to the concentration of salts in water, which influences the osmotic pressure experienced by aquatic organisms. Marine bony fish are typically in a hypertonic environment, leading to water loss through their gills, while freshwater fish are in a hypotonic environment, causing them to gain water. Organisms have adapted various osmoregulatory strategies to cope with these challenges.

Gills and Water Exchange

Gills are specialized respiratory structures in aquatic organisms that facilitate gas exchange and also play a critical role in osmoregulation. In organisms like marine bony fish, gills allow for the diffusion of water and ions, which can lead to significant water loss in a saline environment. Understanding how gills function in different salinities is essential for predicting water loss through osmosis.