B2 Cell Transport

Question 1

What is diffusion?

Answer 1

The net movement of particles from an area of high concentration to an area of low concentration along a concentration gradient

Question 2

3 factors that affect the rate of diffusion

Answer 2

Concentration gradient
Temperature
Membrane surface area

Question 3

How are villi adapted for exchanging substances?

Answer 3

Long and thin (increases surface area)
One cell thick membrane ( short diffusion pathway)
Good blood supply ( maintains a steep concentration gradient)

Question 4

How are the lungs adapted for efficient gas exchange?

Answer 4

Alveoli for a large surface area
Moist membranes to increase the rate of diffusion
Good blood supply to maintain a steep concentration gradient

Question 5

How are fish gills adapted for efficient gas exchange?

Answer 5

Large surface area for gases to diffuse across
Thin layer of cells for a short diffusion pathway
Good blood supply to maintain a steep concentration gradient

Question 6

What is osmosis?

Answer 6

It is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane

Question 7

Give one example of osmosis in a plant

Answer 7

When water moves from the soil into the root hair cell

Question 8

What is active transport?

Answer 8

It is the movement of particles against a concentration gradient- from a dilute solution to a more concentrated solution- using energy from respiration

Question 9

Why is active transport needed in plant roots?

Answer 9

Because the concentration of mineral ions in the soil is lower than inside the root hair cells and the mineral ions must move against the concentration gradient to enter the root hair cells

Question 10

What is the purpose of active transport in the small intestine?

Answer 10

So that the sugars can be absorbed when the concentration of sugar in the small intestine is lower than the concentration of sugar in the blood

Question 11

Explain the movement of particles in diffusion

Answer 11

The particles move down the concentration gradient- from an area of high concentration to an area of low concentration

Question 12

Explain the movement of particles in osmosis

Answer 12

The water moves from an area of lower solute concentration to an area of higher solute concentration

Question 13

Explain the movement of particles in active transport

Answer 13

The particles move against the concentration gradient- from an area of low concentration to an area of high concentration

Question 14

What three factors affect the rate of diffusion?

Answer 14

Difference in concentration
Temperature
Surface Area of the membrane

Question 15

How does the difference in concentration affect the rate of diffusion?

Answer 15

The steeper the concentration gradient the faster the rate of diffusion

Question 16

How does the temperature affect the rate of diffusion?

Answer 16

The higher the temperature, the faster the rate of diffusion

Question 17

How does the surface area of the membrane affect the rate of diffusion?

Answer 17

The larger the membrane surface area, the faster the rate of diffusion

Question 18

Why do single-celled organisms have a large surface area- to-volume ratio?

Answer 18

To allow enough molecules to be transported across their cell membranes to meet their needs

Question 19

When do exchange surfaces warm the most efficient?

Answer 19

When they have…
A large surface area
A thin membrane
A good blood supply

Question 20

What is the effect of osmosis on animal cells?

Answer 20

Animal cells don’t have a cell wall so it will change size and shape when put into solutions that are at a different concentration to the cell contents

Question 21

What could happen to red blood cells during osmosis?

Answer 21

Lose water
Shrink
Gain answer
Swell
Burst in a more dilute solution

Question 22

When cells lose or gain too much water by osmosis they don’t function efficiently so what must happen to avoid this?

Answer 22

Blood plasma and tissue fluid must be kept within strict limits

Question 23

What is the effect of osmosis on plant cells in pure water?

Answer 23

In pure water, the plant cells contents (the cytoplasm and vacuole) push against the cell wall and the cell becomes turgid

Question 24

What do turgid cells do to the plant cell?

Answer 24

Turgid cells are swollen and firm and this allows the plant to be healthy and stand upright

Question 25

What is the effect of osmosis on plant cells in concentrated solutions?

Answer 25

If a plant does not get sufficient water, the cells will be surrounded by a more concentrated solution. This causes the cell contents to lose water by osmosis they shrink and pull away from the cell wall and the cell becomes flaccid

Question 26

What do flaccid cells do?

Answer 26

It makes the plant wilt