B2 Cell Transport

Question 1

What is the meaning of ‘diffusion’?

Answer 1

The spreading out of particles, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Question 2

What is the definition of the word ‘osmosis’?

Answer 2

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Question 3

What is the definition of the phrase ‘active transport’?

Answer 3

The movement of particles from a more dilute solution to a more concentrated solution using energy from respiration.

Question 4

What is the movement of particles like in diffusion?

Answer 4

Particles move down the concentration gradient - from an area of high concentration to an area of low concentration.

Question 5

What is the movement of particles like in osmosis?

Answer 5

Water moves from an area of lower solute concentration to an area of higher solute concentration.

Question 6

What is the movement of particles like in active transport?

Answer 6

Particles move against the concentration gradient - from an area of low concentration to an area of high concentration.

Question 7

Is energy required for diffusion?

Answer 7

No, its a passive process

Question 8

Does osmosis require energy?

Answer 8

Nope, it’s a passive process.

Question 9

Does active transport require energy?

Answer 9

Yes- it uses the energy released by respiration.

Question 10

How is diffusion used in human small intestines?

Answer 10

The nutrients in the small intestine diffuse into the capillaries through the villi.

Question 11

How is diffusion used in human lungs?

Answer 11

Oxygen diffuses from the air in the alveoli into the blood in the capillaries. Carbon dioxide diffuses from the blood in the capillaries into the air in the alveoli.

Question 12

How is diffusion used in human kidneys?

Answer 12

Urea diffuses from cells into the blood for excretion in the kidney.

Question 13

How is diffusion used in fish?

Answer 13

•oxygen from water passing over the gills diffuses into the blood in the gill filaments.
•carbon dioxide diffuses from the blood in the gill filaments into the water.

Question 14

How is diffusion used in plants?

Answer 14

•carbon dioxide used for photosynthesis diffuses into leaves through the stomata.
•oxygen produced during photosynthesis diffuses out of the leaves through the stomata.

Question 15

How is osmosis used in plants?

Answer 15

Water moves by osmosis from a dilute solution in the soil to a concentrated solution in the root hair cell.

Question 16

How is active transport used in humans?

Answer 16

It allows sugar molecules to be absorbed from the small intestine when sugar concentration is higher in the blood than in the small intestine.

Question 17

How is active transport used in plants?

Answer 17

It’s used to absorb mineral ions into the root hair cells from more dilute solutions in the soil.

Question 18

What factors affect the rate of diffusion?

Answer 18

• difference in concentration
•temperature
•surface area of the membrane

Question 19

How does difference in concentration affect the rate of diffusion?

Answer 19

The steeper the concentration gradient, the faster the rate of diffusion.

Question 20

How does temperature affect the rate of diffusion?

Answer 20

The higher the temperature, the faster the rate of diffusion.

Question 21

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

Answer 21

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

Question 22

Do single celled organisms have a small surface area-to-volume ratio?

Answer 22

No! They have a large surface area-to-volume ratio.

Question 23

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

Answer 23

So enough molecules can be transported across their cell membranes to meet their needs.

Question 24

Do multicellular organisms have small surface area-to-volume ratios?

Answer 24

Yes, they do!

Question 25

Why do multicellular organisms have a small area-to-volume ratio?

Answer 25

They have specialised organ systems and cells to allow enough molecules to be transported into and out of their cells

Question 26

What factors make exchange surfaces work most efficiently?

Answer 26

•large surface area
•thin membrane
•good blood supply

Question 27

Why do you have villi in the small intestine?

Answer 27

To absorb nutrients.

Question 28

What adaptations do villi in the small intestine have to make them more efficient?

Answer 28

•network of capillaries
•large surface area due to folding
•thin wall (one cell thick)
•good blood supply

Question 29

Why is there alveoli in the lungs?

Answer 29

For gas exchange.

Question 30

What adaptations do alveoli in the lungs have to be more efficient?

Answer 30

•network of capillaries provides a good blood supply
•has a large surface area
•is moist
•is one cell thick (short diffusion pathway)

Question 31

What is the purpose of fish gills?

Answer 31

For gas exchange.

Question 32

What adaptations do fish gills have to be more efficient?

Answer 32

•large surface area to increase diffusion
•a network of capillaries (good blood supply)

Question 33

What is the purpose of root hair cells?

Answer 33

To uptake water and minerals.

Question 34

What are the adaptations of root hair cells to make them more efficient?

Answer 34

•lots of mitochondria (to take in mineral ions by active transport)
•large surface area (helps efficient absorption of water and mineral ions)