Biology- Diffusion, Osmosis and Active Transport

Question 1

Osmosis is….

Answer 1

the movement of water from an area of high water concentration to
an area of low water concentration through a partially permeable membrane.

Question 2

Hypotonic=

Answer 2

low concentration- not many ions

Question 3

Hypertonic=

Answer 3

high water concentration

Question 4

A bigger number of moles means…..

Answer 4

a stronger solution

Question 5

Isotonic is ……

Answer 5

when the water concentration both sides
of the partially permeable
membrane is the same. Therefore there is no net movement of water.

Question 6

Diffusion-

Answer 6

The movement of a substance from an area
of high concentration to an area of low concentration.
Molecules have ‘moving’ energy. This is called kinetic energy and this is what drives the diffusion. This is a passive process ie no external source of energy is required.

Question 7

Active transport is…..

Answer 7

the movement of molecules from a region of lower

concentration to a region of higher concentration using energy from respiration.

Question 8

Is a cell membrane permeable, impermeable or partially permeable?

Answer 8

Partially permeable

Question 9

Is a cell wall permeable, impermeable or partially permeable?

Answer 9

Permeable

Question 10

Explain why red blood cells burst if they are put into water.

Answer 10

There is a very low water concentration inside the red blood cell so water molecules from outside
the cell diffuse very quickly, so much so that the
cell bursts.

Question 11

Exchange surfaces are specialised in many organisms:

Answer 11

They have a high surface area to volume ratio
They are thin so they have a short distance for diffusion
In animals, the surface area has an efficient blood supply
In land animals, there is ventilation for gas exchange