1B Transport in Cells

Question 1

Whats the definition of diffusion

Answer 1

The spreading out of particles from an area of high concentration to an area of lower concentration

Question 2

How does dissolved substances eg.oxygen move in and out of cells by diffusion

Answer 2

They diffuse through cell membranes as they are small enough

Question 3

What affects the rate of diffusion

Answer 3

• Temperature
• Concentration
• Surface Area

Question 4

Why is the rate of diffusion faster when the concentration is higher

Answer 4

The net movement from one side is greater

Question 5

Why is the rate of diffusion faster when the temperature is higher

Answer 5

The particles have move energy

Question 6

Why is the rate of diffusion faster when the surface area is higher

Answer 6

More particles can move through at once

Question 7

What is osmosis

Answer 7

The movement of water molecules through a partially permeable membrane from an area of high water concentration to an area of lower water concentration

Question 8

How do you investigate the different concentrations of sugar/salt solution on potato cells

Answer 8

Place identical potato cylinders in a beaker of concentrated sugar solution(eg1.omol/dm3) and in a beaker of pure water. Leave for 24hrs then measure percentage change in mass after drying off.

Question 9

How do you calculate the rate of osmosis

Answer 9

Divide change in mass by time taken (g/min)

Question 10

How do you calculate the percentage change in plant tissue mass

Answer 10

(change in mass/ original mass) x 100

Question 11

What does the point when the line of best fit crosses the x -axis mean when investigating the effect of sugar solution in potato cells

Answer 11

Where the concentration of sugar is same in and out of the potato. You can estimate the concentration of solution inside the potato

Question 12

What is active transport

Answer 12

Movement of particles against a concentration gradient using energy by respiration

Question 13

How does the structure of the root hair cell help it absorb mineral ions and water

Answer 13

It has a big surface area

Question 14

What do root hair cells use active transport for and why

Answer 14

To absorb mineral ions as they need it for healthy growth

Question 15

What does the gut absorb into the blood by active transport and why

Answer 15

Sugar for use in cellular respiration

Question 16

What out of diffusion, osmosis and active transport requires energy

Answer 16

Active transport

Question 17

What are some examples of substances that move in and out of cells by diffusion

Answer 17

Oxygen and carbon dioxide or transferred between cells and The environment during gas exchange

Question 18

Why can gases and dissolved substances diffuse directly into the cell across the cell membrane is in a single celled organism

Answer 18

They have a large surface area compare to the volume so enough substances can be changed to supply the body

Question 19

Why do you multi cellular organisms have specialised Exchange services/transport systems

Answer 19

They have a smaller surface area: volume ratio so not enough substances can diffuse supply The volume

Question 20

How’s the exchange services adapted to maximise effectiveness

Answer 20

• thin membrane-short distance to diffuse
• large surface area-lots of substances diffuse at once
• Exchange services have a lot of blood vessels-to get stuff into/out of the blood quickly
• gas exchange and animals are often ventilated-air moves in and out

Question 21

How is alveoli adapted to maximise the exchange of gases in the lungs in mammals

Answer 21

An enormous surface area
Moist lining for dissolving gases
Very thin walls
Good blood supply

Question 22

How does villi adapt to aid the absorption of nutrients in the gut

Answer 22

A single layer of cells are cells

Very good blood supply to assist quick absorption

Question 23

How are leaves adapted to maximise the exchange of gases in plants

Answer 23

-stigmata underneath leaf-carbon dioxide in and oxygen/water out
-flatten shape-increases area so it’s more affective
– Air spaces inside leave – increases area so more chance of CO2 to get into cells

Question 24

How are girls adapted to maximise the exchange of gases in fish

Answer 24

Water containing outage and enter for your mouth and out through gills

• made of thin plates(Gill filaments)
• Gill filaments covered in teeny structures called lamellae
• blood flow through lamellae is in One Direction and water in opposite direction
• large concentration gradient between water and blood