Unit 3 Test

What is the definition of diffusion?

• The movement of particles from an area of high concentration to an area of low concentration.

• The process of a liquid turning into a gas.

• The movement of water across a semipermeable membrane.

• The process of a solid turning into a liquid.

Diffusion occurs ______ the concentration gradient (membrane), from high to low.

• up

• down

• across

Which of the following is an everyday example of diffusion?

• Air freshener spreading through a room

• Water boiling

• Ice melting

At equilibrium, the concentration of the substance is equal throughout the space. True or False?

• True

• False

What happens to perfume molecules when they are sprayed in a room?

• They evaporate and spread throughout the room.

• They remain in the bottle.

• They change color.

• They become solid.

Define osmosis.

• Osmosis is the movement of water molecules through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

• Osmosis is the process of active transport of ions across a membrane.

• Osmosis is the diffusion of gases from a region of high pressure to low pressure.

• Osmosis is the movement of solute particles from a region of high concentration to low concentration.

A semipermeable membrane allows some substances to pass through (usually water) but not others.

• True

• False

Osmosis is the primary way water moves into plant roots from the soil.

• True

• False

The key difference between diffusion and osmosis is:

• Diffusion involves the movement of particles from high to low concentration, while osmosis specifically involves the movement of water across a semipermeable membrane.

• Diffusion requires energy input, whereas osmosis does not.

• Diffusion occurs only in liquids, while osmosis occurs in gases.

• Diffusion is a passive process, while osmosis is an active process.

In the cornstarch and iodine experiment, iodine molecules diffuse because:

• they are attracted to cornstarch.

• they move from an area of high concentration to low concentration.

• they react with water.

• they are heated.