Fluid Balance - Aquatic Organisms: Osmoregulators

Question 1

What are osmoregulators?

Answer 1

They maintain ion and water levels at an optimum level which is either hypertonic or hypotonic to their surroundings. Tissues are not isotonic to the surroundings but are hypotonic. They regulate their salt and water levels to maintain optimum levels regardless of the concentration of their surroundings.

Question 2

Describe freshwater organisms.

Answer 2

Have low levels of dissolved ions. It is hypertonic to the cells of organisms. Water moves into organs by osmosis and ions move out of organs by diffusion.

Question 3

Describe amoeba’s adaptations to a freshwater environment.

Answer 3

They have contractile vacuoles that collect and expel excess water.

Question 4

Describe mammals’ adaptations to a freshwater environment.

Answer 4

The reabsorption of slats in the kidneys occurs.

Question 5

Describe invertebrate adaptations to a freshwater environment.

Answer 5

They have nephridial organs such as nephrons in the kidney.

Question 6

Describe freshwater fish and their adaptations that classify them as osmoregulators.

Answer 6

1. Large amounts of dilute urine due to a high filtration rate in the kidneys, a large number of glomeruli and reabsorption of ions in the kidneys by active transport.
2. There is an active uptake of ions through the gills.
3. Their scales or mucus layer prevents water from entering the body.

Question 7

What are 4 disadvantages of freshwater organisms?

Answer 7

1. Higher water concentration in surroundings than cells.
2. Cells are hypertonic to their surroundings.
3. Water moves into cells by osmosis.
4. Salts are lost by diffusion.

Question 8

What are 3 adaptations of freshwater organisms?

Answer 8

1. Large amounts of dilute urine due to a high filtration rate.
2. Reabsorption of salts and ions in the kidneys by active transport.
3. Cells can actively pump salts into cells.