MEMBRANES

Question 1

plasma membrane

Answer 1

sepeartes cell from exteranl environment
regualtes transport of substances in and out
has antigens so organisms immune system can recofnise cell as itselfs cell
cell communication and signaling

Question 2

cristae (mitochondria inner membrane)

Answer 2

gives mitochondria large surface area for aerobic respiration to occur to release energy

Question 3

thylakoid (chloroplast inner membrane)

Answer 3

houses chlorophyll for photosynthesis

Question 4

fluid mosaic model

Answer 4

phospholipid bilayer
channel proteins
peripheral proteins
carrier proteins
cholesterol
carbohydrate
glycoproteins
glycolipid

Question 5

phospholipid bilayer

Answer 5

hydrophobic tails inwards allows hydrophobic substances (steroid hormones) through
hydrophillic heads outwards to touch cytoplasm
this makes membrane partially permeable

Question 6

cholestrol in membrane

Answer 6

embedded within bilayer
regulates membrane fluidity

Question 7

glycolipid in membrane

Answer 7

has receptors
for cell signaling
helps cell adhesion
has antigens

Question 8

glycoprotein membrame

Answer 8

cell recognition to prevemt immune system from destroying cell

Question 9

channel proteins membrane

Answer 9

span entire bilayer
has hydrophillic interior
allows water soluble molecules to diffuse through

Question 10

carrier proteins membrane

Answer 10

can change shape or position to transfer molecules from one end to the other

Question 11

peripheral proteins membrane

Answer 11

hormone receptors
structural role
enzymes

Question 12

diffusion

Answer 12

the net movement of particles from an area of high conc to an area of low conc down a conc gradient

Question 13

what is active transport in membrane

Answer 13

carrier protein transport substances from inside cell to outside (eg ca2+) against the conc gradient so enery is neede

Question 14

how does active transport work in membrane

Answer 14

molecule/ion attatches to receptor site on carrier protein
ATP binds to receptor on protein
ATP undergoes hydrolysis making phosphate and ADP
The phosphate attaches to protein causing it to change shape to other side to release molecule/ion

Question 15

osmosis

Answer 15

movement of water molecules from an area of high water potential to an area of low water potential through a partially permeable membrane

Question 16

water potential of pure water

Answer 16

0kPa

Question 17

osmosis of rbc in plasma

Answer 17

the rate is constant as the water potential inside and outside the cell is the same

Question 18

osmosis of rbc in water

Answer 18

water potential inside cell is lower than outside cell
so water molecules move into rbc via osmosis
hydrostatic pressure inside cell increases
weak cell membrane cannot withstand pressure
so rbc bursts (haemolysis)

Question 19

osmosis of rbc in glucose solution

Answer 19

water potential inside cell is higher than outsude
so water moves out of rbc into solution
this causes cell to shrink

Question 20

osmosis of plant cell in water

Answer 20

water pressure is lower inside cell than outside
so water moves in via osmosis
hydrostatic pressure inside cell increases
plant cell becomes turgid due to strong cell wall

Question 21

osmosis of plant cell in glucose

Answer 21

water pressure is lower outside cell
so water moves out of cell via osmosis
so protoplast pulls away from cell wall
cell becomes plasmolysed

Question 22

endocytosis: phagocytosis

Answer 22

phagocyte approaches bacteria
cell invaginates around bacterium
bacterium enclosed by vesicle pinched off membrane
(ATP needed to form vesicle and move them using motor proteins along cytoskeleton)

Question 23

endocytosis: pinocytosis

Answer 23

endocytosis of liquids

Question 24

exocytosis

Answer 24

vesicles moves along cytoskeleton via motor proteins to cell membrane
vesicle fuses with cell membrane
fused site opens allowing substance to be excreted out of cell
(ATP is needed for formation of vesicle and movement of vesicle)