Movement Across Membranes

Question 1

Diffusion

Answer 1

Is the spreading of molecules from an area of high concentration to an area of low concentration
This is a passive process, that doesn’t require energy

Question 2

Factor effecting rate of concentration

Answer 2

Concentration gradient: greater the difference, faster the rate of diffusion
Temperature: higher the temperature, more the KE the particles have
Distance: shorter the distance, faster the diffusion
Size of particles: the smaller the molecule, faster the diffusion
Surface: larger the surface area, higher the rate of diffusion

Question 3

Osmosis

Answer 3

Osmosis is the net movement of water molecules across a partially permeable membrane, from an area of high concentration to an area of low concentration

Question 4

Cell placed in pure water ( plant and animal)

Answer 4

As the water potential is higher outside the cell than inside the cell
The water moves into the cell
In plant cells: the cytoplasm pushes against the cell wall, this is called turgor
In animal cells: there is no Cell wall, so the cell bursts from pressure

Question 5

Cells placed in a concentrated solution

Answer 5

Higher water potential in the cell, so the water moves out of the cell
Plant cell: the water moves out of the cell making it flaccid, cytoplasm and cell membrane is pulled away from the cell wall
Animal cell: the water moves out of the cell, and the cell becomes crenated, cytoplasm decreases

Question 6

Active transport

Answer 6

Active transport is the process by which molecules are transport from Ana tea of low concentration to an area of high concentration using energy released form respiration
Cells that use active transport contain a lot of mitochondria as it requires a lot of energy
It is achieved by carrier proteins