B1.3.1 Simple and Facilitated Diffusion Flashcards

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1
Q

Diffusion is an example of

A

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

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2
Q

In diffusion the motion of the particles is described as

A

random motion

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3
Q

In diffusion the direction of particle movement is

A

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

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4
Q

Molecules which can diffuse through the phospholipid bilayer include

A

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

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5
Q

Facilitated diffusion and diffusion differ because

A

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

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6
Q

Facilitated and diffusion are similar because

A

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

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7
Q

Molecules which do not diffuse easily across the phospholipid bilayer are

A

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

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8
Q

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

A

the hydrophobic fatty acids tails of the phospholipid bilayer

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9
Q

Name the two types of protein molecules involved in facilitated diffusion

A

carrier and channel proteins

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10
Q

Carrier proteins transport

A

molecules like glucose

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11
Q

How do carrier proteins transport molecules like glucose?

A

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

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12
Q

Channel proteins transport…

A

water soluble ions

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13
Q

How do channel proteins transport molecules like water soluble ions?

A

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

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14
Q

State 3 factors that affect the rate of diffusion

A

surface area, concentration gradient and thickness of exchange surface

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15
Q

For maximum diffusion what adaptations does the exchange surface need

A

large surface area
Large concentration gradient
Thin - short diffusion distance

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16
Q

Name 2 exchange surfaces in living organisms (humans)

A

alveoli and villi

17
Q

Where does diffusion take place in living organisms

A
  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
Q

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

A

doubles

19
Q

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

A

no change

20
Q

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

A

decreases 4 fold/quarter

21
Q

what is a protein channel filled with?

A

water

22
Q

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

A

binding sites

23
Q

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

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