Diffusion, Osmosis and Active transport

Question 1

Diffusion

Answer 1

Is a movement of particles from an area of high concentration to an area of lower concentration. It happens in both solutions and gases.

Question 2

Diffusion rate

Answer 2

• The bigger the concentration gradient, the faster the diffusion rate
• Higher temperature also give a faster diffusion rate, since particles have more kinetic energy, so move faster
• A surface area of the membrane

Question 3

What can diffuse trough cell membrane?

Answer 3

Only very small molecules like oxygen, glucose, amino acids and water.
Big molecules such as starch and protein cannot fit trough.
The larger the surface area of the membrane, faster the diffusion rate is.

Question 4

Osmosis

Answer 4

Is a movement of water molecules across a partially permeable membrane from an area of higher concentration of water to an area of lower concentration of water. It is a type of diffusion.

Question 5

Partially permeable membrane

Answer 5

Membrane with very small holes in it. Only small molecules can pass trough e.g. water

Question 6

Active transport

Answer 6

Some substances need to be absorbed against the concentration gradient. It requires energy from respiration to make it work.

Question 7

Root hair-active transport

Answer 7

The concentration of minerals is usually higher in the root hair than in the soil. Therefore, root hair cannot use diffusion to take up minerals.

Question 8

Active transport in human body

Answer 8

Is used in the gut where there is a low concentration of nutrients but high concentration of nutrients in blood. E.g glucose

Question 9

Dilute solution

Answer 9

Have a high concentration of water.

Question 10

Concentrated solution

Answer 10

Have a low concentration of water.

Question 11

The cell wall prevents…

Answer 11

a plant cell from bursting and the cell becomes turgid.

Question 12

Turgid

Answer 12

When a cell becomes swollen. In hypotonic solution. It is normal for plant cell but it will burst an animal cell.

Question 13

Flaccid

Answer 13

In isotonic solution. It is normal for the animal cell but not for the plant cell. It causes the vacuole to shrink and the plant will no longer be firm and rigid.

Question 14

Urea

Answer 14

Is a waste product, produced inside the cells. It diffuses out of the cells into a blood plasma and excreted by the kidneys.

Question 15

Cytoplasm is made up of…

Answer 15

chemicals dissolved in the water. It is a concentrated solution of salts and sugars.

Question 16

Hypotonic

Answer 16

If the concentration of solutes in the solution outside the cell is lower than the concentration inside the cell. The solution is hypotonic to the cell.

Question 17

Isotonic

Answer 17

The concentration of solutes in the solution in and outside the cell is the same. The solution is isotonic to the cell.

Question 18

Hypertonic

Answer 18

The concentration of solutes in the solution outside the cell is higher than the concentration inside the cell. The solution is hypertonic to the cell.

Question 19

Plasmolysed

Answer 19

When the cell shrinks. In hypertonic solution. The cells die quickly unless the osmotic balance is restored.

Question 20

Turgor

Answer 20

The pressure caused by vacuole, which swells and presses the cytoplasm against the cell wall. The pressure builds up until no more water can enter.

Question 21

Turgor makes the cells…

Answer 21

hard and rigid, which keeps the leaves and stems of the plant rigid and firm.

Question 22

Glucose is actively absorbed out of…

Answer 22

gut and kidney tubules into the blood.

Question 23

The single-celled organism has…

Answer 23

a large surface area to volume ratio. All the necessary exchanges occur across its surface area.

Question 24

Multicellular organisms have…

Answer 24

many organ systems, specialised for exchanging materials.

Question 25

The effectiveness of an exchange surface is increased by:

Answer 25

• a large surface area that is thin(provide a short diffusion path)
• having an efficient blood supply
• being ventilated(for gaseous exchange), to maintain a steep gradient