Diffusion and Osmosis

Question 1

What are the types of membranes

Answer 1

1. Permeable: allows all substances to pass
2. Impermeable: substances cannot pass through
3. Selective (semi): allows some but not all substances

Question 2

What is Diffusion

Answer 2

The spreading out / movement of molecules from an area of high conc. to an area of low conc.

Question 3

What are everyday examples of diffusion

Answer 3

smell of perfume
cigarette smoke
O2 and CO2 in and out of leaf/cell

Question 4

Does diffusion require energy

Answer 4

no it is passive

Question 5

What is osmosis

Answer 5

The movement of H2O molecules across a selectively permeable membrane from a region of high water conc. to an area of low water conc.

Question 6

How is this similar to diffusion

Answer 6

Passive - no energy required

Question 7

Examples of osmosis

Answer 7

Absorption of water by plant roots

Re-absorption of water by kidneys

Question 8

What happens to an animal cell in an isotonic solution

Answer 8

external environment and cell have the same conc.
water moves in and out of cell at the same rate
cell remains intact

Question 9

What happens to an animal cell in a hypotonic solution

Answer 9

Hypo- soln less conc than cytoplasm (more h2o and less solute outside)
water from outside will move into the cell
enlarges cell and it can burst or die

Question 10

What happens to an animal cell in a hypertonic soln.

Answer 10

External environment less conc. (more water in cell )
water will move out of cell
cell shivels up (crenation) and may die

Question 11

What do plant and animal cells have in common in terms of osmosis

Answer 11

both have a semi-permeable cell membrane

Question 12

What does the plant cell have that the animal cell does not

Answer 12

Plant cell is also enclosed by a fully permeable cell wall

Question 13

What is Turgor pressure in a plant cell

Answer 13

the force of the swollen cell membrane against the plant cell wall
Plant cell becomes turgid in a solution less conc. (solutes) than the cell

Question 14

What is plasmolysis in a plant cell

Answer 14

the cell membrane pulls away from the cell wall

Plant cell becomes flaccid in a soln. more conc (solutes ) than the cell

Question 15

How can you prevent micro-organisms growing on food

Answer 15

Foods like fish and meat are placed in a very salty solution , the micro-organisms will lose water and die