Biological membranes

Question 1

why facilitated diffusion via proteins require no metabolic energy

Answer 1

.particles have their own kinetic energy
.and it is the movement down concentration gradient

Question 2

why cant glucose or galactose pass through phospholipid bilayer by simple diffusion

Answer 2

.phospholipid acts as barrier
.and glucose molecules are too big

Question 3

how phospholipid bilayer keeps stability

Answer 3

.hydrophobic tails form bilayer separating two aqueous regions
.contains cholesterol which regulates fluidity

Question 4

role of membranes wihtin the cell

Answer 4

.form around organelles
.separates organelles from cyto
.site of chemical reaction
.provides attachment sites for enzymes
.allows formation of conc gradient

Question 5

role of membrane in RER

Answer 5

.maintains different conditions from cyto
.separates proteins from cyto
.holds ribo in place

Question 6

what is required to break glycosidic bonds

Answer 6

.water
.enzyme

Question 7

why does low pH cause pigment to leak out of beetroot cells

Answer 7

.low pH denatures proteins
.so permeability to pigment has increased

Question 8

how to get a more accurate value for the pH at which the red pigment begins to leak out of the beetroot cells.

Answer 8

.use pH buffer range with smaller intervals
.use pHs close to pH6

Question 9

why does progesterone able to pass through plasma membrane

Answer 9

.it is a lipid
.so diffuses through bilayer

Question 10

things that can pass through bilayer

Answer 10

.lipids
.water
.oxygen
.carbon dioxide

Question 11

how do charged ions pass through bilayer

Answer 11

.via channel or carrier protein

Question 12

what is ATP made of

Answer 12

.one adenine group
.three phosphate groups
.one ribose group

Question 13

How does the fluid mosaic model describe the structure of plasma membranes?

Answer 13

.phospholipid bilayer
.hydrophilic head facing out
.hydrophobic tail facing in
.phospholipids free to move
.proteins scattered randomly

Question 14

Explain how the structure of phospholipid molecules allows for the formation of plasma membranes.

Answer 14

.phosphate is hydrophilic
.bonds with water
.fatty acid tails are hydrophobic
.head face towards water
.tails face towards other tails away from water
.so a bilayer is formed

Question 15

structure of RER

Answer 15

.has phospholipid bilayer
.network of cisternae
.covered with ribosomes
.membrane continuous with nuclear envelope

Question 16

the structural difference between alpha and beta glucose molecules.

Answer 16

.alpha has H above and OH below ring on C1

.beta has OH above and H below ring on C1

Question 17

effect of sulthiame on
the reabsorption of sodium ions in the PCT?

Answer 17

.fewer H+ ions in PCT cells
.less co-facilitated diffusion of Na+ ions into cells
.no active transport of Na+ ions into blood

Question 18

which macromolecule does a plant need both nitrogen and phosphorus?

Answer 18

DNA/RNA

Question 19

how does flooding affect soil water potential

Answer 19

.make it more negative

Question 20

variables that are controlled in beetroot experiment

Answer 20

.temp of ethanol solutions
.age of beetroot
.volume of beetroot pieces
.skin removed
.time taken to wash slices
.pH
.same colorimeter filter

Question 21

how repeating investigation improves it

Answer 21

.you can find mean
.you can remove annomailes

Question 22

simple diffusion graph vs active transport graph

Answer 22

.simple diffuision = straight line
.active transport = curved line reaches a plateau due to carrier proteins being saturated

Question 23

DNP effects on simple diffuson and active transport

Answer 23

.SD = no effect due to not needing ATP

AT - slower due to it needing ATP

Question 24

how to represent data on to graph

Answer 24

.line graph due to variables being continuous
.conc on x
.% on y

Question 25

State how the student could reduce the uncertainty of their data.

Answer 25

.use more accurate apparatus

Question 26

osmosis

Answer 26

.net movement of water across a partially permeable membrane down a water potentail gradient

Question 27

importance of osmosis in plant support.

Answer 27

.water enters vacuole
.pressure aganist cell wall
.keeps cell turgid

Question 28

why it was necessary to calculate percentage change in mass for beetroot

Answer 28

.because they all have different masses
.and so allows comparison