2.1.5 Biological Membranes – Passive Transport

Question 1

What does partially permeable mean?

Answer 1

That some substances can pass through that membrane and others cannot

Question 2

What is passive transport?

Answer 2

Movement across a membrane that requires no energy/ATP.

Question 3

What is diffusion?

Answer 3

The net movement of particles from a region of higher concentration to a region of lower concentration. It is a passive process and does not require ATP.

Question 4

Which three types of molecules can move by diffusion?

Answer 4

• Small, non-polar molecules such as oxygen and carbon dioxide.
• Small, polar molecules, such as water and urea – these travel more slowly.
• Lipid soluble molecules e.g. steroids or steroid hormones.

Question 5

What types of molecules cannot move by diffusion?

Answer 5

• Large molecules
• Charged substances e.g. ions

Question 6

What is facilitated diffusion?

Answer 6

The movement of molecules from an area of higher concentration to an area of lower concentration, via protein channels or carrier proteins.

Question 7

How do channel proteins and carrier proteins move large or charged substances across the membrane?

Answer 7

The proteins form water filled channels across the membrane.

Question 8

Name two substances that move by facilitated diffusion.

Answer 8

Glucose
Amino acids
Ions (any example allowed)

Question 9

What type of proteins are protein channels and carrier proteins?

Answer 9

Intrinsic/integral proteins