Biology - Diffusion, Osmosis, And Active Transport

Front 1

What is diffusion?

Back 1

The movement of molecules or particles from a high area of concentration to a low area of concentration

Front 2

What is osmosis?

Back 2

Water molecules moving from a high area of concentration to a low area of concentration, through a partially-permeable membrane

Front 3

What is active transport?

Back 3

The movement of ions or molecules across a cell membrane into a region of high concentration, assisted by carrier protons and requiring an input of energy

Front 4

What do energy requirements vary with?

Back 4

Activity levels, age, gender and pregnancy

Front 5

How are turgid cells a means of support?

Back 5

Turgid cells give strength to a plant and have a cell wall to stop them bursting.
If a cell becomes flaccid then the plant will wilt. Eventually flaccid cells become plasmalysed, killing the cell

Front 6

How does a surface area-volume ratio affect the rate of movement of substances in and out of cells?

Back 6

Larger surface area → molecules have more surface through which they can diffuse →faster rate of reaction

Front 7

How does temperature affect rate of movement of substances in and out of cells?

Back 7

High temperature → particles have more energy → faster rate of movement

Front 8

How does concentration gradient affect rate of movement of substances in and out of cells?

Back 8

Larger difference between particles in and out of cells (larger concentration gradient) faster rate of movement

Front 9

Describe an osmosis experiment on a non living system?

Back 9

1. Cut and weigh two roughly equal pieces of potato
2. Put one if distilled and one in salt water
3. After 15 seconds weigh them
4. The in salt water will have lost mass whereas the one in distilled water would have gained mass as it had a concentration inside it

Front 10

Describe an osmosis experiment on a living system?

Back 10

1. Peel away the onion epidermis and cut into squares
2. Mount on slides different amount of sucrose solution
3. Cells in a hypotonic solution will be turgid because through osmosis water will flow into the cell
4. Cells in an isotonic solution is neither turgid nor flaccid, water is moving in and out at the same rate
5. Cells in a hypertonic will be flaccid/plasmolised because water will out through osmosis

Front 11

What is a hypotonic solution?

Back 11

Solution with a higer concentration of water than the cells vacuole

Front 12

What is an isotonic solution?

Back 12

Solution with the same concentration of water than the cells vacuole

Front 13

What is a hypertonic solution?

Back 13

Solution with a lower concentration of water than the cells vacuole