5.1 Osmosis and Tonicity

Question 1

How does water move across cell membranes?

Answer 1

Water moves freely across cell membranes through ion channels and aquaporins

Question 2

What is osmosis?

Answer 2

Osmosis is the movement of water across a membrane in response to a solute concentration gradient, moving to dilute the more concentrated solution.

Question 3

What is osmotic equilibrium?

Answer 3

occurs when water concentrations are equal throughout the body, with no net movement of water.

Question 4

What is osmolarity?

Answer 4

the number of osmotically active particles per litre of solution, expressed in osmoles per liter (OsM) or milliosmoles per litre (mOsM).

Question 5

What is tonicity?

Answer 5

Tonicity describes how a solution affects cell volume. Solutions can be hypotonic (cell swells), hypertonic (cell shrinks), or isotonic (no change).

Question 6

What do isosmotic, hyperosmotic, and hyposmotic mean?

Answer 6

Isosmotic means two solutions have equal osmolarity, hyperosmotic means a solution has higher osmolarity, and hyposmotic means a solution has lower osmolarity.

Question 7

What happens to a cell in a hypertonic solution?

Answer 7

The cell loses water and shrinks.

Question 8

How do osmolarity and tonicity differ?

Answer 8

Osmolarity refers to the number of solute particles in a solution, while tonicity refers to the effect a solution has on cell volume.

Question 9

What happens to a cell in a hypotonic solution?

Answer 9

The cell gains water and swells.

Question 10

What happens to a cell in an isotonic solution?

Answer 10

The cell stays the same size, as there is no net movement of water.