Diffusion & Osmosis

Question 1

Why is it important to regulate the concentration of individual ions?

Answer 1

For cell function

Question 2

Why is it important to regulate the overall concentration of cells?

Answer 2

To determine the distribution i& movement did water between cells & extracellular compartments

Question 3

Name 3 inorganic ions dissolved in water

Answer 3

• Na+ (sodium)
• K+ (potassium)
• Mg2+ (magnesium)

Question 4

Name 3 organic solutes

Answer 4

Ionic solutes:
- Amino acids/proteins

Non-ionic solutes:
- Glucose
- Urea

Question 5

What is osmotic concentration?

Answer 5

The number of miles of dissolved & osmotically active solutes per litre of solution (moles/l or molar)

Question 6

What is osmotic concentration also referred to as?

Answer 6

Osmolarity

Question 7

What are the units of osmolarity?

Answer 7

Osmoles
1 Osmol = 1 mole solute/l

Question 8

What are isosmotic solutions?

Answer 8

• Where 2 solutions have equal osmotic concentrations
• No net movement of solutes between 2 compartments

Question 9

When the concentrations in compartments are not equal, where do solutes move to?

Answer 9

Move by passive diffusion from hyperosmotic solution to hyposmotic solution

Question 10

What are hyperosmotic solutions?

Answer 10

Greater concentrations

Question 11

What are hyposmotic solutions?

Answer 11

Lower concentrations

Question 12

What are 2 other reason there will be a movement of solutes after there is equal osmotic concentrations?

Answer 12

• unequal electrical gradients
• Unequal concentrations of specific ions

Question 13

What 3 things does passive diffusion depend on?

Answer 13

• Overall concentration of solutions
• Electrical gradients
• Concentrations of individual ions

Question 14

What is active transport?

Answer 14

the movement of ions/molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy how

Question 15

What is the Na-K ATPase pump?

Answer 15

• Transports 3 Na+ out
• Transports 2 K+ in
• Maintains electrical potential across membranes

Question 16

What is a semi-permeable membrane?

Answer 16

• When 2 solutions with different concentrations are separated by a membrane that is permeable to water but not solutes

Question 17

What is osmosis?

Answer 17

The net movement/diffusion of solvent molecules through a semi-permeable membrane from a region of high water potential to a region of low water potential, in the direction that tends to equalize the solute concentrations on the two sides

Question 18

Interactions of water, ions & osmotic concentration means that animals have to regulate what 3 things?

Answer 18

• Cell volume
• Ion concentrations
• Osmotic concentrations