Human Biology Ques Unit 1 Chp 2 Movement of substances into and out of cells

OBJQ

What is osmosis?

Net movement of water molecules from higher water potential to lower water potential (dilute solution to concentrated solution) down the concentration gradient.

EXAMPLE: Absorption of water and mineral ions by root hair cell

OBJQ

What is active transport?

M/V of molecules from lower concentration to higher concentration against the concentration gradient by the use of energy, a pump (large protein molecules) or by the help of a carrier protein 

EXAMPLE: Absorption of glucose in the intestine

OBJQ

What is diffusion?

Net movement of particles (molecules/ions) from a region of higher concentration ti a region of lower concentration down the concentration gradient 

EXAMPLE: Diffusion of O₂ & CO₂ in alveolar membrane

OBJQ

What are the factors affecting the rate of diffusion? (movement of substances in and out of cell)

Concentration gradient (steeper = faster diffusion rate)

Surface area to volume ratio (Large surface area to volume ratio = faster diffusion rate)

Distance (Greater the distance = slower the rate of diffusion)

Temperature (Higher temperatue = higher diffusion rate)

+A level 

Explain about 3 types of transport, the type of energy requirement and an example if possibl

Passive transport 

• Osmosis 

• Diffusion (Use KE)

• Facilitated diffusion (carrier and channel protein) 

(Doesn’t use ATP energy) 

Active transport (uses ATP energy)

Bulk transport 

• Endocytosis (phagocytosis and pinocytosis)

• Exocytosis (synapse)