Diffusion

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What for of transport if diffusion and why?
Passive- Doesn't require energy as it is a natural motion
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What is diffusion?
The overall movement of particles from an area of high concentration to an area of low concentration, until an equilibrium has been reached
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Why does diffusion happen?
Particles in gases and liquids are constantly moving due to kinetic energy, their movements are random and unequal. However because of the constant movement, the particles eventually even out,reaching an equilibrium.
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How does size of diffusion pathway effect the rate of diffusion?
The particles are constantly colliding at high speeds, which slows them down. So larger the diffusion pathway, the slower the rate of diffusion because there are more collisions.
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How does temperature effect the rate of diffusion?
The higher the temperature, the more kinetic energy and so they move at higher speeds, increasing the rate of diffusion
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How does concentration gradient effect the rate of diffusion?
The greater the conc difference between the 2 regions (steeper conc grad), the rate will be faster due to the overall movement being larger
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What type of molecules can diffuse through the plasma membrane?
Non-polar molecules (eg. Oxygen) and molecules with both a negative and positive charge (e.g.. Water) however these move a lot slower.
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Why is the plasma membrane known as partially permeable?
Because it is selective to which molecules can pass through it
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What factors effect diffusion across the plasma membrane?
Surface area (the larger the plasma membrane SA, the higher the rate of diffusion) Thickness of membrane (The thinner the exchange surface, the faster the rate of diffusion)
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What is facilitated diffusion?
Diffusion across a membrane through protein channels
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How many different types of molecules can pass through 1 protein channel?
1 because they are selectively permeable to a certain type of molecule or ion
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What other protein can be involved in facilitated diffusion?
Carrier proteins
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How come carrier proteins can be involved in passive transport?
Because when it is going down a concentration gradient, it doesn't require energy
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What other factor effects facilitated diffusion (apart from the ones already previously mentioned)?
The number of channel proteins present in the membrane, the more in the membrane, the faster the diffusion rate
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Card 2

Front

What is diffusion?

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The overall movement of particles from an area of high concentration to an area of low concentration, until an equilibrium has been reached

Card 3

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Why does diffusion happen?

Back

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Card 4

Front

How does size of diffusion pathway effect the rate of diffusion?

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Card 5

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How does temperature effect the rate of diffusion?

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