Eco 1D Remediation

Diffusion across the cell membrane

Diffusion

The cytoplasm consists many different substances dissolved in water. These particles move from areas of high concentration to areas of low concentration.

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This is called diffusion.​

Module 3B: Cell Transport & Processes

Passive Transport

Multiple Choice

How do molecules move during diffusion?

• From high concentration to low concentration

• From low concentration to high concentration

Diffusion

Molecules will move across the cell membrane until equilibrium is reached. Equilibrium is where concentrations are equal on both sides.

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Diffusion is the movement of random molecular movements and does not require the use of energy (ATP).

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Molecule movement that does not require energy is called passive transport.​

Module 3B: Cell Transport & Processes

Passive Transport

Multiple Choice

What is the goal of diffusion called when molecules are equally spread out?

• Samenss

• Equilibrium

Multiple Choice

The picture below is an example of _________________.

• osmosis

• isotonic

• diffusion

• active transport

Multiple Choice

Equilibrium?

• a large  amount of substance on  side of the cell and a small amount on the other side

• a small  amount of substance on  side of the cell and a large amount on the otherside

• equal amount of substance on either side of the membrane  

• no particles on either side of the a cell membrane

Facilitated Diffusion

Some molecules (such as charged ions & large molecules like glucose) cannot cross the cell membrane. Instead they use channels (proteins inside of the cell membrane) to let them pass.

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The movement of these molecules using special protein channels is known as facilitated diffusion. Although it is fast & specific, facilitated diffusion is still passive transport.

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No energy (ATP) is required for this process.​

Module 3B: Cell Transport & Processes

Passive Transport

Multiple Choice

Which type of diffusion uses a protein to help molecules get across?

• Simple diffusion

• Facilitated diffusion