Diffusion

Question 1

Substances may move into and out of cells via osmosis.

True or False?

Answer 1

False

Substances may move into and out of cells via DIFFUSION

Question 2

Diffusion is the spreading of the __________ of any substance in solution, or particles of a ______, resulting in the net movement from an area of _________ concentration to an area of __________ concentration

Answer 2

Particles
Gas
Higher
Lower

Question 3

What are some of the substances transported in and out of cells by diffusion in gas exchange?

Answer 3

Oxygen

Carbon dioxide

Question 4

DIFFUSION

Of the waste product ______ from cells into the blood ________ for excretion in the ________

Answer 4

Urea
Plasma
Kidney

Question 5

What are the factors that affect the rate of diffusion?

Answer 5

• Difference in concentrations (concentration gradient)
• Temperature
• Surface area of the membrane

Question 6

A ______-celled organism has a relatively large _______ area to _______ ratio. This allows sufficient transport of __________ into and out of the cell to meet the needs of the __________

Answer 6

Single
Surface
Volume
Molecules
Organism

Question 7

In multicellular organisms, what does the smaller surface area to volume ratio mean and what does it allow?

Answer 7

Surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules to be transported into and out of cells for the organisms needs

Question 8

The effectiveness of an exchange surface is increased by…?

Answer 8

• Having a large surface area
• A thin membrane, to provide a short diffusion path
• Having sufficient blood supply (animals)
• Being ventilated (gaseous exchange)(in animals)

Question 9

How do you calculate the surface area to volume ratio?

Answer 9

Vol

Question 10

Why does diffusion occur quickly in the small intestine?

Answer 10

It is covered in villi which increases the surface area. The villi have a high concentration gradient and the blood supply has a lower concentration gradient.