Topic 2 Gas Exchange and diffusion

Question 1

define diffusion sk

Answer 1

it is the net movement of particles form an area of HIGHER concentration to LOWER concentration. It is a passive process.

Question 1

factors affecting diffusions? sk

Answer 1

temperature: particles gain more kinetic energy with increases the frequency off successful collisions.

surface area:more space for particles to move across

thickness of the surface: thinner surface quicker movement, thicker surface longer movement

concentration gradient: steeper gradient quicker rate of diffusion

Question 2

what are the features in the lungs that make for efficient gas exchange? sk

Answer 2

short diffusion pathway

steep concentration gradient

large surface area: volume ration

Question 3

why do we have cell membranes?

Answer 3

to control what substances enter and exit the cell

contain the cell contents and organelles/
compartmentalise individual cell contents

communicate with external environment

site of chemical reactions

allows the cell to change shape

transport and packaging within a cell

Question 4

Meaning of:
hydrophobic
hydrophilic
semi permeable
bilayer

Answer 4

hydrophobic - repels water

hydrophilic -attracts water

semipermeable -certain things can move through not all

bilayer - has two layers

Question 5

what are cell membranes made of

Answer 5

lipids thus most are impenetrable to water soluble substances

however water soluble and other molecules can pass into cell through passage ways composed of proteins

Question 6

what do the symbols mean in fixed law calculation
(c1- c2)
rate = P x A x ———-
T

Answer 6

P= permeability constant
( c1 - c2) = difference in concentration
T= thickness of exchange surface area
A= Surface area

Question 7

what is the definition of osmosis and how/ why does it occur

Answer 7

.It occurs became of a concentration gradient of water.