Diffusion Flashcards

1
Q

Describe the difference between Passive and Active transport

A

Passive transport doesn’t require additional energy from ATP, whereas active transport does

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2
Q

Is diffusion active or passive transport

A

passive

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3
Q

Define diffusion

A

Diffusion is the passive net movement of particles from an area of a higher concentration, to an area of a lower concentration, until they’re evenly distributed

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4
Q

What does it mean when particles have reached equilibrium

A
  • Particles have become equally distributed
  • The concentration of particles is approximately equal
  • There is no net movement
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5
Q

What is movement down the concentration gradient

A

From a higher to a lower concentration

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6
Q

Why is saying that diffusion requires no energy inaccurate

A

With no energy, the particles will not move

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7
Q

When is the rate of diffusion the highest

A

When there is the biggest difference in the concentration

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8
Q

How do you increase the rate of simple diffusion

A
  • Increase the concentration gradient
  • Increase the SA of the membrane
  • Decrease the thickness of the membrane
  • Increase the temperature
  • Decrease the size of the particles
  • Change the state of matter to a gas
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9
Q

As you climb higher, mountain climbers often become more fatigued

Explain why, using your knowledge of diffusion and the role of oxygen

A
  • As you climb higher, the concentration of oxygen in the atmosphere decreases
  • This results in a lower concentration gradient between the cells and the blood
  • Therefore the rate of diffusion decreases
  • The higher you climb, the colder the air temperature is
  • Therefore body temperature will decrease, so particles will have less kinetic energy, reducing the rate of diffusion
  • Less oxygen diffuses into cells, so less aerobic respiration occurs, producing less ATP
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10
Q

State Fick’s law

A

The rate of diffusion is proportional to both the surface area and concentration difference, and is inversely proportional to the thickness of the membrane

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11
Q

In what process do non-lipid soluble molecules diffuse across the phospholipid bilayer

A

Facilitated diffusion

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12
Q

Describe what is meant by facilitated diffusion

A

Some molecules that cannot pass through the phospholipid bilayer, diffuse across the cell membrane via a transport protein

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13
Q

Describe the function of channel proteins

A

These proteins open and close to allow substances through the membrsne

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14
Q

Describe the function of carrier proteins

A

These proteins change shape to move substances across the membrane

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15
Q

Describe how to increase the rate of facilitated diffusion

A
  • Increase the concentration gradient
  • Increase the SA of the membrane
  • Decrease the thickness of the membrane
  • Increase the number of carrier/channel proteins
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16
Q

Describe what happens to the rate of facilitated diffusion as external concentration increases, and internal concentration remains 0.

A
  • Increases->the rate of diffusion is proportional to the concentration gradient
  • Plateaus-> the number of carrier proteins becomes a limiting factor
17
Q

Why doesn’t the simple diffusion graph plateau

A

The particles move directly across the phospholipid bilayer and so the rate of diffusion remains directly proportional to the concentration of

18
Q

Describe how substances move across cell-surface membranes by facilitated diffusion.

A
  • Carrier / channel protein;
  • (Protein) specific / complementary to substance;
  • Substance moves down concentration gradient;
19
Q

As external concentration of a substance increases, the rate of uptake into the cell initially increases before reaching a plateau.
Explain how this suggests the substance is entering the cell through facilitated diffusion and not by simple diffusion

A

As a plateau is reached, the channel proteins would be saturated and so rate of diffusion cannot increase any further. If it were occurring by simple diffusion, the relationship between rate and extracellular concentration would be linear.