Cells

YOU ARE LEARNING:

Active Transport

Active transport moves substances from low to high concentration, and so requires energy.

This shows what happens in active transport

It's not the same as what happens in osmosis and diffusion.

True or false? In active transport, particles go from higher concentration to lower concentration.

In active transport, particles in fact move from lower concentration to higher concentration

They move from when there are already fewer particles to where there are already more particles!

This is an image of diffusion

Here particles move from higher to lower concentration - the opposite direction to active transport.

Now, the image also shows the direction of the concentration gradient. Particles in diffusion move _________________ the concentration gradient?

A) in the same direction as B) in the opposite direction to

Particles in diffusion and osmosis move along the concentration gradient

The concentration gradient is the direction from higher to lower concentration.

Now, this is an image of active transport again. Particles in active transport move _________ the concentration gradient.

A) along B) against

In active transport, particles move against the concentration gradient

They go from lower concentration to higher concentration.

So active transport is in many ways "opposite" to diffusion and osmosis. What do you think we might call osmosis and diffusion with a single term?

Now, imagine you have to stuff more clothes into a suitcase which is full already. Is this more similar to active transport or passive transport?

A) Active transport B) Passive transport

Stuffing that clothes into the suitcase will likely make you huff and puff. It requires you to...

A) spend money. B) lie back and relax. C) spend energy.

Moving against the concentration gradient requires energy

That means that active transport requires energy, as opposed to passive transport, like osmosis and diffusion.

To recap! In active transport, particles move against the concentration gradient

That means they go from lower concentration to higher concentration.

Active transport requires energy

Passive transport, like osmosis and diffusion, does not.

True or false? This image shows an example of active transport.

Summary! Active transport requires enery

It moves particles against the concentration gradient.

Example 1

Sugar molecules move from your gut to your blood where there is already a higher concentration of sugar molecules than in the gut.

Example 2

Ions move from the soil into plant roots where there is already a higher concentration of ions than in the soil.