Diffusion & Osmosis

Question 1

Diffusion

Answer 1

The movement of molecules from a region of high concentration to a region of low concentration.

Question 2

A characteristic of Diffusion

Answer 2

Passive (No energy required)

Question 3

What makes diffusion faster?

Answer 3

High temperature
Short distance
Big concentration difference

Question 4

Example of Diffusion?

Answer 4

Gaseous exchange in alveoli of lungs

Oxygen, and Carbon dioxide moving between the alveoli and the blood capillaries in the lungs

Question 5

Osmosis

Answer 5

Movement of water molecules from a region of high water concentration to a region of low water concentration across a semi-permeable membrane.

Question 6

Why is Osmosis special?

Answer 6

i) Movement of water

ii) Across a semi-permeable membrane

Question 7

A characteristic of Osmosis

Answer 7

Passive (No energy required)

Question 8

Example of Osmosis

Answer 8

Water reabsorption by the nephron

Question 9

Semi-Permeable Membrane

Answer 9

Permits some substances but not others.

Question 10

Why are Cell Membranes Semi-Permeable?

Answer 10

Because they allow the passage of water but also the passage of certain solutes. (Dissolved Substances)

Question 11

Plasmolysis

Answer 11

Shrinking of cytoplasm from the cell wall due to loss of water by osmosis

Question 12

When does Plasmolysis occur?

Answer 12

When plant cells have a higher water concentration than their surroundings and water flows out by osmosis

Question 13

Example of Plasmolysis

Answer 13

Flower will wilt

Question 14

Tugor

Answer 14

The pressure of the cell contents against the cell wall

Question 15

When does Tugor occur?

Answer 15

When plant cell has a lower water concentration than their surroundings and water flows in by osmosis.

Question 16

Example of Tugor

Answer 16

Cells in pure water

Question 17

How does a plant remain Turgid?

Answer 17

Can remain turgid by taking in as much water as they lose via osmosis

Question 18

Why are plants able to remain Turgid?

Answer 18

Because of their cell wall. It gives plant cells good support.

Question 19

What happens if cells lose their turgidity?

Answer 19

They will wilt

Question 20

Can animal cells become Turgid? What would happen if they did?

Answer 20

No, they have no cell wall, so the cell would burst.

Question 21

How does high salt and sugar concentration involve osmosis?

Answer 21

High salt and sugar concentration can remove water from micro-organisms (bacteria) by osmosis.

Question 22

Example of food preservation.

Answer 22

Bacon can be preserved by placing it in a salt solution. The salt causes the tissue and bacteria to lose water by osmosis.

Question 23

Active Transport

Answer 23

Movement of molecules across a cell membrane against a concentration gradient

Question 24

Characteristic of Active Transport

Answer 24

Energy is required

Question 25

Example of Active Transport

Answer 25

Reabsorption of glucose/vitamins/amino acids in the nephron of the kidney.