Diffusion and osmosis

Question 1

What is diffusion?

Answer 1

• Diffusion is a passive process that occurs as a movement of particles from a region with high concentration of particles to the area with low concentration

Question 2

What is Osmosis?

Answer 2

A passive process of movement of water molecules across a semi-permeable membrane - from an area of high concentration of water molecules to an area of low concetration of water molecules

Question 3

What does “solvent” mean?

Answer 3

Solvent is the liquid into which the solute is poured and dissolved (eg water)

Question 4

What does “solute” mean?

Answer 4

Substance that is dissolved or put into the solvent (eg salt or sucrose)

Question 5

What are solutions made of?

Answer 5

Solutions are made of solvent and solute

Question 6

What is tonicity?

Answer 6

Measure of pressure - describes whether a solution will cause water to move in or out of cell

Question 7

Three types of tonicity

Answer 7

• Hypotonic solution - one solution has a lower concentration of solute
• Hypertonic solution - one solution has a higher concentration of solute than another
• Isotonic solution - both solution have the same concentration of solute

Question 8

What happens to red blood cells when encountering hypo- and hypertonic solutions?

Answer 8

• Hypo- (less concentrated than the cell water) red blood cells will swell, can cause the cells to burst
• Hyper- (more concentrated than the cell water) red blood cells can shrink or crenate

Question 9

How does cell membrane work with osmosis?

Answer 9

• Cell needs to regulate osmosis to survive
• the cell membrane is a semi-permeable membrane which controls the movement of substances in and out of the cell
• Active transport - energy is requires to move molecules in and out of the cell

Question 10

What is Active Transport and 1 example of where it occurs

Answer 10

• Active transport requires energy to move molecules against a concentration gradient
• The energy is provided from ATP
• E.g. water moving from plant roots upwards to different cells via root pressure

Question 11

Osmosis in plant cell

Answer 11

Osmotic pressure creates the main support of plant leaves - the cell walls without water aren’t strong enough to support the weight of the plant and leaves wilt

Question 12

What is osmoregulation?

Answer 12

Balancing of the sugar and salt concentrations in cells

Question 13

Examples of osmosis in food prep

Answer 13

• Use of salt, sugar or fruit juice
• water moves from the cells into the salt solution causing the tissues to become dehydrated and destroying bacteria