Topic 2 mistakes

Question 1

Use fixed law of diffusion to explain adaptations for effective gas exchange ?

Answer 1

rate of diffusion is proportional to surface area, alveoli in lungs have large surface area

Rate of diffusion is proportional to difference in concentration. Breathing maintains a difference in concentration as well as constant blood flow which maintains concentration gradient

rate of diffusion is inversely proportional to diffusion distance, walls of aveoli and capillaries are one cell thick

rate of diffusion is proportional to diffusion constant, cell membrane are relatively permeable to non polar molecules (?)

Question 2

if a solute does not enter a cell at that means it is what ?

Answer 2

membrane is impenetrable to solute

Question 3

why is the rate of osmosis different in a cell surface membrane and phospholipid bilayer - most basic answer 2 marks

Answer 3

water can move across a phospholipid bilayer Aswell a channel proteins ( simple and or facilitated diffusion )

cell surface membrane is more permeable to water than artificial phospholipid bilayer membrane

Question 4

compare and contrast active transport with diffusion ?

Answer 4

similarities - both molecules move through phospholipid bilayer
In both molecules can move through proteins

differences- active transport requires vesicles where as diffusions does not

Active transport requires energy form ATP where as diffusion is passive

diffuse occurs down the concentration gradient where as active transport is against the concentration gradient

Question 5

compare and contrast exocytosis with endocytosis

Answer 5

both requite vesicular transport

they both requite energy form ATP as active processes

Both transport substances that can’t enter by facilitated or simple diffusion

Differences-

exocytosis requires vesicles for Golgi apparatus fusing with cell surface where as exocytosis involves forming a vesicle

Question 6

use fixed law to explain the adaptations of mammalian gas exchange surfaces

Answer 6

rate of diffusion is proportional to surface area - alveoli have large surface area

rate of diffusions is proportional to difference in surface area/ concentration gradient - breathing and constant blood flow maintains a difference in gas concentrations

rate of diffusion is inversely proportional to diffusion distance - walls of alveoli and capillary are one cell thick

diffusion distance is reduced due to flattened cells forming alveoli and capillary walls

rate of diffusion is proportional to diffusion constant - cell membranes are relatively permeable to non polar gas molecules.

Question 7

using graph describe the effect of temperature on cell membrane permeability ?

Answer 7

increase in temp increase in permeability of cell membrane

is increase in permeability linear ? non linear ? (do not say faster or slower)

Question 8

now explain the effect of temperature on cell membranes

Answer 8

increased kenetic energy resulted in increase molecule movement
reference - phospholipid moving

membranes proteins may become denatured

betalanin/ pigment can escape form cell when cell surface disrupted

Question 9

what factors can make a beetroot practical more reliable

Answer 9

appropriate standardisation of source of beetroot tissue ( strong matches/ small source of beetroot)

washing/ rinsing beetroot thoroughly to remove excess beetroot pigment

water bath to maintain temp / change temperature)

use smaller interval temperatures

reference to calibration of colorimeter

reference to a control variable- time beetroot left in water bath