3.2.3.2 - Simple and Facilitated Diffusion Flashcards Preview

SHHS - Science - NEW AQA A-Level Biology (Year 1) > 3.2.3.2 - Simple and Facilitated Diffusion > Flashcards

Flashcards in 3.2.3.2 - Simple and Facilitated Diffusion Deck (23):
1

Diffusion is an example of

passive transport - energy comes from natural, inbuilt motion of particles

2

In diffusion the motion of the particles is described as

random motion

3

In diffusion the direction of particle movement is

from an area of high concentration to an area of lower concentration - until equilibrium is reached

4

Molecules which can diffuse through the phospholipid bilayer include

non-polar, small molecules e.g. oxygen and carbon dioxide

5

Facilitated diffusion and diffusion differ because

facilitated diffusion requires a special protein molecules e.g. carrier or channel protein

6

Facilitated and diffusion are similar because

they are both passive and molecules move with their concentration gradient (high to low)

7

Molecules which do not diffuse easily across the phospholipid bilayer are

large, charged ions and polar molecules e.g. glucose

8

What prevents large, charged and polar molecules diffusing across the plasma membrane

the hydrophobic fatty acids tails of the phospholipid bilayer

9

Name the two types of protein molecules involved in facilitated diffusion

carrier and channel proteins

10

Carrier proteins transport

molecules like glucose

11

How do carrier proteins transport molecules like glucose?

glucose binds to the carrier specifically, carrier changes shape, releasing it onto the other side of the membrane

12

Channel proteins transport...

water soluble ions

13

How do channel proteins transport molecules like water soluble ions?

ion binds causing a change in the shape of the channel allowing the ion to enter the cell

14

State 3 factors that affect the rate of diffusion

surface area, concentration gradient and thickness of exchange surface

15

For maximum diffusion what adaptations does the exchange surface need

large surface area
Large concentration gradient
Thin - short diffusion distance

16

Name 2 exchange surfaces in living organisms (humans)

alveoli and villi

17

Where does diffusion take place in living organisms

1. alveoli - exchanging oxygen and carbon dioxide
2. Villi - exchange soluble molecules into the blood
3. Leaf (stomata) - carbon dioxide and oxygen
4. Roots - water

18

How would diffusion be affected if the alveoli surface area is doubled

doubles

19

How would diffusion be affected if the surface area is halved but the oxygen concentration gradient is doubled

no change

20

How would diffusion be affected if the oxygen concentration is halved and the total thickness of the exchange surface is doubled

decreases 4 fold/quarter

21

what is a protein channel filled with?

water

22

What do carrier proteins and channel proteins have in order to transport molecules across the membrane?

binding sites

23

How do substances move across the cell surface membrane by facilitated diffusion

1. Carrier/channel protein;
2. (Protein) specific/complementary to substance;
3. Substance moves down concentration gradient;