3. Movement into and out of cells

Question 1

Define diffusion

Answer 1

The net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient as a result of their random movement

Question 2

Where does the energy for diffusion come from

Answer 2

The kinetic energy of random movement of molecules and ions.

Question 3

What are three uses of diffusion of gases and solutes in living organisms

Answer 3

1) Gas exchange
2) Nutrient uptake
3) Waste removal

Question 4

4 factors that affect diffusion

Answer 4

1) Surface area
2) Temperature
3) Concentration Gradient
4) Distance

Question 5

What is osmosis

Answer 5

The net movement of water molecules from a region of high water potential to a region of low water potential through a partially permeable membrane.

Question 6

How are plants supported

Answer 6

By the pressure of water inside the cells pressing outwards on the cell wall

Question 7

What happens when a plant cell is placed in a hypotonic solution

Answer 7

• Water enters the cell through osmosis.
• This causes the cells to swell and become turgid.
• This increases turgor pressure, giving the plant structure and support.

Question 8

Define turgidity

Answer 8

Turgid means swollen or hard

Question 9

Define turgor pressure

Answer 9

The pressure of the cell contents against the cell wall.

Question 10

What happens when a plant cell is put in an isotonic solution

Answer 10

-There is no net movement of water
- The cells remain in a flaccid state
- Turgor pressure is relatively lower resulting in less structural support for the plant

Question 11

What happens when a plant cell is put in a hypertonic solution

Answer 11

• Water exits the cells, resulting in a decrease of turgor pressure.
• As the cell looses water, the cytoplasm shrinks away from the cell wall (plasmolysis)

Question 12

Define flaccid

Answer 12

Describes plant cells that are relatively less firm but also not collapsing

Question 13

Uses of osmosis in plants

Answer 13

Helps plants take up water from the soil in their roots.

Question 14

Uses of osmosis in animals

Answer 14

Regulates water balance in cells

Question 15

What is active transport

Answer 15

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration, using energy from respiration

Question 16

Two uses of active transport

Answer 16

1) Ion uptake by root hairs
2) Nutrient uptake in animal cells

Question 17

What role do protein carriers play in active transport

Answer 17

Move molecules or ions across a membrane during active transport.