Transport Through Membrane

Question 1

What are the functions of membranes

Answer 1

Protect cell
Control entrance and exit of substances 
Maintain ion concentrations of various substances 
Selectively permeable 
All this maintains homeostasis

Question 2

What are the four types of transport across membranes?

Answer 2

1) Diffusion
2) Osmosis
3) Facilitated Diffusion
4) Active Transport

Question 3

What are Passive transport and active transport?

Answer 3

Passive:
- doesn’t use energy
Eg. Diffusion, facilitated Diffusion and osmosis

Active:
- cell does use energy
Eg. Protein pumps, endocytosis and exocytosis

Question 4

What is Diffusion?

Answer 4

Movement of molecules from an area of high concentration to low concentration.

Movement from one side of a membrane to another, un-facilitated

Diffusion continues until equilibrium is reached

Question 5

What is osmosis?

Answer 5

Diffusion of water through a selectively permeable membrane

Water moves from high to low concentration

Question 6

What are the three types of tonicity?

Answer 6

Hypotonic: one solution has a lower concentration of solute than another

Hypertonic: one solution has a higher concentration of solute than another

Isotonic: both have be same concentrations of solute

Question 7

What is Facilitated Diffusion?

Answer 7

Diffusion of specific particles through transport proteins found in the membrane

Transports larger or charged molecules

From high to low concentration

Question 8

What are the two types of active transport?

Answer 8

Endocytosis: taking bulky material into a cell

• uses energy
• cell membrane in-folds around particle
• forms food vacuole and digests food
• this is how white blood cells eat bacteria

Exocytosis: forces material out of he cell in bulk

• membrane surrounding the material fuses with the cell membrane
• cell changes shape- needs energy
• EX: hormones or wastes released from cell