Movement of molecules

Movement of molecules

by Aanisa Riyaz

​Diffusion

​Diffusion is the movement of molecules from a high concentration to a low concentration gradient. ​Examples of diffusion in everyday life includes :

• ​Smell of perfume diffuses through the air.

• ​CO₂ diffuses out of blood into lungs.

• ​O₂ diffuses into blood from lungs.

• ​CO₂ diffuses into leaf of a plant and O₂ diffuses out of the leaf during photosynthesis.

​Osmosis

​Osmosis is a form of diffusion. Osmosis is the movement of water molecules down a concentration gradient, through a partially permeable membrane. Therefore, for osmosis, you need :

​

• ​A concentration gradient

• ​A partially permeable membrane.

• ​Water molecules

Multiple Choice

Diffusion is the movement of molecules from :

• A lower concentration to a higher concentration

• A higher concentration to a lower concentration

Multiple Choice

Osmosis is a form of :

• Energy

• Force

• Diffusion

• Active transport

Multiple Select

What is the difference between osmosis and diffusion?

• Osmosis is the movement of water molecules. 

• Osmosis is the movement of air.

• Diffusion needs a partially permeable membrane.

• Diffusion is the movement of molecules down a concentration gradient.

Multiple Select

Diffusion occurs in :

• Solids

• Liquids

• Gases

​Active Transport

​Active transport is the movement of molecules against a concentration gradient through a partially permeable membrane using energy from respiration. Examples of active transport are :

• ​ Uptake of glucose in the small intestine

• ​Uptake of ions by root hair cells.

Multiple Choice

Active transport requires a membrane

• True

• False

Fill in the Blanks

One difference between active transport and diffusion is that molecules move

(against/down) a concentration gradient in active transport.

Multiple Choice

Which of these processes require energy?

• Osmosis

• Active transport

• Diffusion

Open Ended

Give an example of active transport.