Diffusion

Question 1

Diffusion =

Answer 1

High to low.

Question 2

Define diffusion?

Answer 2

The net movement of molecules or ions from a region where they are highly concentrated to one where the concentration is lower.

Question 3

How does diffusion occur?

Answer 3

All particles are constantly in motion due to kinetic energy that they possess the motion is random and particles bounce off of each other. The particles naturally move from high to low.

Question 4

Does diffusion require ATP?

Answer 4

No it is passive.

Question 5

What factors effect the rate of diffusion?

Answer 5

Ficks Law:

• concentration gradient
• diffusion pathway
• surface area.

Question 6

Ficks Law =

Answer 6

Surface Area X Difference in Conc
Diffusion is proportional to = —————————————–
Length of diffusion path

Question 7

In cells what else affects diffusion?

Answer 7

• the nature of the plasma membrane, it composition and number of pores
• the size and nature of diffusing molecules, small non polar molecules can diffuse unaided.

Question 8

What increases diffusion according to Ficks Law?

Answer 8

• a short diffusion pathway
• a high concentration gradient
• a large surface area to volume ratio

Question 9

How are cells adapted for diffusion?

Answer 9

• epithelial cells lining the villi posses micro villi on their surface membrane about 0.6 micrometers creates a short diffusion pathway.
• very thin cell walls creates a short diffusion pathway.
• its well supplied with blood vessels as the blood carries the nutrients away it creates a concentration gradient.
• villi and micro villi increase the SA to volume ratio.
• they are able to move which helps to maintain a concentration gradient.

Question 10

A summary of diffusion?

Answer 10

An example of a molecule transported by diffusion is small polar molecules such as oxygen. It occurs down a concentration gradient and in both direction. It does not require proteins or ATP.