Transport in and out cells

Question 1

What are the ways in which substances cross cell-surface membranes?

Answer 1

• diffsuion
• at
• osmosis

Question 2

Why is beetroot used?

Answer 2

• vacuole contains pigment
• if you cut up a beetrot
  
  • lots will leak out
  • have to cut through many cells
• if you was the slices the leakage will stop, as the membranes of undamaged cells are in tact

Question 3

How can membrane permeability be investiagated with washed slices of beetroot~?

Answer 3

• immersion in differnet solvents, such as ethanol, propanone, detergrents, and different salts
• temp of surroudnings

Question 4

How cna these tests be carried out semi-quantitatively and quantitatively?

Answer 4

• semi quantitatively
  
  • compare intensity of the colours in the test tubes and rank tthem
  • or match them against colour standard made by diluting beetroot juice
• quantitaviley
  
  • colorimetyry

Question 5

How can model cells be used to investigate transport

Answer 5

• model cells could be made from gelatine, or netter from technical agar
• • cut into different shapes and sizes

Question 6

How is the model cell test done?

Answer 6

• prepared with alkaline soln and stained with a pH indicator
• when placed into dilute acid, the indicator changes colour as the acid diffused into the block
• when the last bit of colour has chanmging the middle of the ‘cell’, the acid has reached all parts of the cell

Question 7

How is rate of diffusion in the moidel cells done?

Answer 7

• measuring time taken for the whole block to change colour
• or waiting for a set period of time and cutting the blocks open to see how much of the block has changed colour

Question 8

What is visking tubing and how is it used?

Answer 8

• dialysis tubing
• used to create model cells
• permeable to water glucose and salts, but impermeable to large molecuels

Question 9

How is osmosis investigated?

Answer 9

• place in solutions with different conc of salt and measures p[ercentage change in mass