B2.2 : Movement

Question 1

Diffusion

Answer 1

• Diffusion is the net movement of particles from an area of high concentration to an area of low concentration
• The greater the difference in concentration, the faster the rate
• No energy needed
• No membrane needed (but commonly has a membrane)
• All particles have a natural desire to move (brownian motion) which allows for passive transport
• Eg. smells moving around (perfume)
• hypertonic to hypotonic solution

Question 2

Factors affecting diffusion

Answer 2

• Temperature
• Size of molecules
• Concentration of the solute

Question 3

Osmosis

Answer 3

• Net movement of water molecules from a region of higher water concentration (dilute) to a region of lower water concentration (concentrated)
• No energy needed (passive movement)
• Aquaporin in membrane allows for water to pass through
• Type of passive movement

Question 4

Passive transport

Answer 4

• No energy (ATP) needed
• High concentration to low concentration
• Diffusion, Facilitated diffusion, osmosis

Question 5

Facilitated Diffusion

Answer 5

• High concentration to low concentration
• Has a channel protein that molecules pass through
• Some molecules such as glucose and sodium ions are unable to pass through the layer of cell membranes but with the aid of a channel protein, they are able to be transported

Question 6

Solute

Answer 6

Substance dissolved in another substance (commonly liquid)

Question 7

Solvent

Answer 7

Liquid that dissolves a solute

Question 8

Hypertonic Solution

Answer 8

Greater concentration or number of solute particles outside a membrane than there are inside it.

Question 9

Isotonic Solution

Answer 9

concentration or number of solute particles outside a membrane is the same as inside it. There will be no net movement of water

Question 10

Hypotonic Solution

Answer 10

Lower concentration or number of solute particles outside a membrane than there are inside it.

Question 11

Cells in a hypertonic solution

Answer 11

Animal cell - water will move out of the cell so the cell will become shrivelled and eventually die due to dehydration and the lack of water
Plant cell - water will move out of the cell so the plant cell will be plasmolysed and go through plasmolysis which is when the cell membrane moves away from the cell wall leading the plant to wilt and eventually die. The cells become damaged

Question 12

Cells in a isotonic Solution

Answer 12

Animal Cell - there will be no net movement of water. Animal cells want to be in an isotonic solution (no effect on cell - natural occurance)
Plant cell - there will be no net movement of water. Plant cells will become flaccid. Due to the lack of turgor pressure the plant will start to wilt but if you spray water at it it can stand up again

Question 13

Cells in a hypotonic solution

Answer 13

Animal cell - water will move into the cell so the animal cell will explode due to the lack of cell wall and the increase in water
Plant cell - water will move into the cell so the plant cell will become turgid which will allow it to stand up. This is where the plant wants to be and the natural occurrence of a plant

Question 14

Transport in root hair cells

Answer 14

Osmosis - water and minerals from the soil into the cell

Question 15

Transport in capillaries

Answer 15

one-cell thick wells which allows exchange of substances between capillaries and tissue cells to occur rapidly through diffusion

• oxygen and dissolved food substances diffuse from capillaries into tissue fluids and cells
• Metabolic waste products diffuse from the cells into tissue fluids and then into blood capillaries

Question 16

Transport in unicellular organisms

Answer 16

oxygen and nutrients can diffuse through cell surface membrane and easily reach all parts of the cell. Metabolic waste can also diffuse out and be removed from the cell

Question 17

Transport in red blood cells

Answer 17

Oxygen diffuses from the lungs into the RBCs, where it binds to haemoglobin.

Question 18

Transport in palisade cells

Answer 18

Water evaporates from the mesophyll cells into air spaces in the leaf through stomata through diffusion as the water vapour is diffusing out of the leaf.
carbon dioxide diffuses in
oxygen diffuses out

Question 19

Active Transport

Answer 19

1. Requires energy
2. Uses a protein pump (ATP)
3. Low concentration to high concentration
4. Bulk transport