Chapter 5: 5.3

Question 1

What is diffusion?

Answer 1

is the net or overall movements of particles (atoms, molecules or ions) from a region of low concentration to region of higher concentration.

• and it takes place until there is a concentration gradient between the two areas

Question 2

What are two modes of transport/movement of substances between cells and their environment?

Answer 2

Passive movement

Active movement

Question 3

What is the different between passive movement and active movement?

Answer 3

Passive movement = utilities the energy from natural particles rather than the energy of other sources.

Question 4

Why does diffusion happen in a gas or liquids? How does particles diffuse?

Answer 4

this is because the particles have kinetic energy (are moving).

• particle movement is random and happens when equal distribution of particles eventually become unequally distributed.

Question 5

What is simple diffusion?

Answer 5

is diffusion that happens in the absence of a membrane considered

Question 6

What factors effect the rate of diffusion?

Answer 6

Temperature
Concentration difference
PH

Question 7

How does temperature affect the rate of diffusion?

Answer 7

The higher the temperature the higher the rate of diffusion = This is because particles have more kinetic energy and move higher speeds

Question 8

How does Concentration Gradient effect the rate of diffusion?

Answer 8

The greater the concentration difference between two regions the faster rate of diffusion…. this is because the overall movement from higher concentration to lower concentration

Question 9

How does Concentration Gradient effect the rate of diffusion?

Answer 9

The greater the concentration difference between two regions the faster rate of diffusion…. this is because the overall movement from higher concentration to lower concentration

Question 10

What is a concentration difference?

Answer 10

Is the concentration gradient which goes from low to high concentration - diffusion happens up it

Question 11

What is facilitated diffusion?

Answer 11

Diffusion that happens across a membrane through channel

Question 12

Why does phospholipid bilayers have channel proteins?

Answer 12

This is to allow on-polar molecules and ions to pass through

Question 13

Why are membranes that contain protein channels selectively permeable?

Answer 13

This is because the protein channels are specific to a specific one molecules or ion

Question 14

What factors effect the rate of facilitated diffusion?

Answer 14

• temperature
• concentration gradient
• membrane surface area
• thickness
• number of carrier protein present

Question 15

What are the proteins that facilitated diffusion take place in (in the membrane)?

Answer 15

glycosidic proteins

Question 16

True or false - facilitated diffusion does require external energy for it to take place

True or false - facilitated diffusion happens up a concentration gradient

Answer 16

False - facilitated diffusion does not require external energy and facilitated diffusion happens down a concentration gradient.

Question 17

What factors effect the rate at which molecules and ions diffuse across the membrane? How?

Answer 17

surface area - the bigger the area of exchange the faster rate of diffusion

thickness of membrane - the thinner the exchange surface the faster the rate of diffusion

Question 18

How does you calculate rate of diffusion?

Answer 18

Diffusion = distance
————-
time

or = volume
————-
time

Question 19

How does partially permeable part of the membrane work? Why is considered it partially permeable?

Answer 19

• this is because the membrane has hydrophobic interior that repels substances with a positive or negative charge (ions) so they can’t pass through easily
• polar molecules such as water with partial positive and negative charge can diffuse through the membrane but at a slow rate. These can pass the membrane more easily than larger ones

Question 20

How does partially permeable part of the membrane work? Why is it considered to be partially permeable?

Answer 20

• this is because the membrane has hydrophobic interior that repels substances with a positive or negative charge (ions) so they can’t pass through easily
• polar molecules such as water with partial positive and negative charge can diffuse through the membrane but at a slow rate. These can pass the membrane more easily than larger ones

{- Particles can only pass through the phospholipid bilayar if it is permeable to the particles
- Non-polar molecules such as oxygen diffuse through freely down a concentration gradient}

Question 21

How is cells adapted for diffusion?

Answer 21

They are microscopic - smaller cells means faster rate of diffusion. As particles have shorter distance to travel.

Question 22

Why is not a good idea for cell to be big when it comes to diffusion?

Answer 22

• As bigger cell will mean bigger rates of diffusion

- and reactions won’t get their substrates in required distance