Yr 11 - SCB - B2.4 - Transport

Question 1

Define diffusion

Answer 1

Is the net movement of particles down a concentration gradient from a region of high to low [PASSIVE]

Question 2

Define facilitated diffusion

Answer 2

is the movement of large, polar or water soluble particles through a channel protein. It is down a concentration gradient from a region of high to low

Question 3

Define osmosis

Answer 3

Is the the diffusion of water. It Is the net movement of water molecules down a concentration gradient from a region of high to low through a semi-permeable membrane [PASSIVE]

Question 4

Define endocytosis

Answer 4

is the cell membrane engulfing foreign particles and forming a circular body body around it called a endosome around it. Then it is allowed into the cell [ACTIVE]

Question 5

Define exocytosis

Answer 5

Is the reverse of of endocytosis. The Golgi body forms a circular body around the contents, fuses to the cell membrane and then fuses with it to spill/release the contents [ACTIVE]

Question 6

Factors that effect diffusion

Answer 6

Contration gradient - greater the difference of concentration between two areas effects rate. Once equal, net movement is 0.

Particle size - small diffuse faster than large

Temperature - higher temp has more kinetic energy and diffuses faster (up to a point)

Distance - greater distance, rate decreases

Time - longer the time, the more the chance the particles have to diffuse across a membrane

Cell size - larger surface area : volume = faster diffusion

Question 7

Cell (plasma) membrane function/structure

Answer 7

Function- Control the entry/exit of materials. Allows for different environments within cell than outside it. Separates areas within cell that need it.

Structure- Double layer of phospholipids are semi-permeable and only allows small molecules (eg water, CO2) to pass, rest needs help from proteins present

Question 8

Active and passive transport similarities and contrasts

Answer 8

Similarities: both involve the movement of particles through or out/in a cell.

Contrast: Passive transport doesn’t require energy (ATP), active transport does require energy. Passive transport moves molecules WITH the concentration gradient (high to low), while active transport moves molecules AGAINST the concentration gradient (Low to High).

Question 9

How does SA:V surface area : volume effect diffusion

Answer 9

• When the cell increases in size, the volume increases faster than the surface area, because volume is cubed where surface area is squared.
• When there is more volume and less surface area, it takes longer and is less effective
• Because there is a greater area that needs to receive the substance being diffused, but less area for that substance to actually enter the cell.
• This is why cells divide