B3 - Movement into and out of cells

Question 1

What is DIFFUSION? [2]

Answer 1

The net (overall) movement of particles from a region of their higher concentration to a region of their lower concentration as a result of their random movement.

Question 2

What does PASSIVE PROCESS mean and is diffusion a passive process? [2]

Answer 2

• It means it does NOT require energy
• Yes

Question 3

What are 4 factors that affect the rate of diffusion? [4]

Answer 3

1. Diffusion distance
2. Concentration gradient
3. Surface area
4. Temperature

Question 4

How does the diffusion distance affect the rate of diffusion? [1]

Answer 4

• The shorter distance the faster the rate of diffusion as it takes less time to travel a short distance

Question 5

How does the concentration gradient affect the rate of diffusion? [1]

Answer 5

• The greater the difference in concentration between two regions, the faster the net movement of particles and so the faster the rate of diffusion
• The steeper the concentration gradient the faster.

Question 6

How does the surface area affect the rate of diffusion? [1]

Answer 6

• The greater the surface area that the particles have to diffuse across, the faster the rate of diffusion.
• More space for diffusion and more particles can move in a given period of time so faster diffusion rate.

Question 7

How does the temperature affect the rate of diffusion? [1]

Answer 7

• The higher the temperature the more KINETIC ENERGY the particles have so the faster the rate of diffusion.

Question 8

What is OSMOSIS? [2]

Answer 8

The movement of WATER from a higher water potential to a lower water potential across a partially permeable membrane.

Question 9

What does a partially permeable membrane mean? [1]

Answer 9

A selective membrane which only allows certain particles to pass through.

Question 10

What is osmosis all about? [1]

Answer 10

WATER!!

Question 11

When animal cells take in water by osmosis what can happen? [2]

Answer 11

• They swell and burst
• This is because no cell walls
• This is called LYSIS

Question 12

What happens to plant cells when they take in water by osmosis? [1]

Answer 12

They become FIRM or TURGID

Question 13

What is TURGOR PRESSURE? [1]

Answer 13

When the pressure inside the cell increases.

Question 14

What happens to plant cells when they lose water by osmosis? [1]

Answer 14

• They become SOFT or FLACCID
• The plant WILTS

Question 15

What is a PLASMOLYSED CELL? [1]

Answer 15

When the cell contents collapse away from the cell wall.

Question 16

When animal cells lose water by osmosis what can happen? [2]

Answer 16

• Become crinkled
• This is called CRENATED CELL

Question 17

What is ACTIVE TRANSPORT? [2]

Answer 17

The movement of substances from an area of low concentration to an area of high concentration.

Question 18

In active transport are the particles moving up or down the concentration gradient? What does this mean? [2]

Answer 18

• Moving UP the concentration gradient
• This means it requires ENERGY

Question 19

Why does active transport require carrier proteins? [1]

Answer 19

Requires carrier proteins in the cell membrane to get substances across the membrane.

Question 20

In what form of energy does active transport require? [1]

Answer 20

ATP

Question 21

What do cells that carry out a lot of active transport contain lots of? [1]

Answer 21

Mitochondria