Plasma membrane and cell transport1. Give an account of the ways in which molecules and ions move into and out of cells. ....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(Allow 2 lined pages)(Total 10 marks) (2001 Jan)2. The table below refers to four membrane transport processes: diffusion, facilitated diffusion, osmosis and active transport. If the statement is correct, place a tick () in the appropriate box and if the statement is incorrect, place a cross (X) in the appropriate box.ProcessTakes place against aconcentration gradientRequires energy in the form of ATP

Diffusion

Facilitated diffusion

Osmosis

Active transport

(Total 4 marks)(jun2001)3. The diagram below shows the structure of a molecule found in the cell surface membrane (a)Name the type of molecule shown in the diagram......................................................................................................................................(1)(b)Name A and B as labelled on the diagram.A .................................................................................................................................B .................................................................................................................................(2)(c)Region X is said to be hydrophobic. What is meant by the term hydrophobic? ..........................................................................................................................................................................................................................................................................(1)(d)Explain why the cell surface membrane is described as a fluid-mosaic.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 6 marks)(June 2001)4. (a)Explain what is meant by the term diffusion.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)State two factors which influence the rate of diffusion across a cell surface membrane.1 .................................................................................................................................2 .................................................................................................................................(2)(c)Give one way in which active transport differs from diffusion.........................................................................................................................................................................................................................................................................(1)(Total 5 marks) (Jan 2002)5. (a)(i)Explain what is meant by the term facilitated diffusion.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)State two ways in which active transport differs from facilitated diffusion.1 .............................................................................................................................................................................................................................................................................................................................................................................2 ....................................................................................................................................................................................................................................................(2) (Jun 2002)6. The diagram below shows the structure of the cell surface membrane.

(a)The cell surface membrane is composed of a phospholipid bilayer. Explain why tile phospholipids in the bilayer are arranged with the fatty acid tails pointing inwards and the phosphate heads outwards.......(3)(b)The diagram has been magnified three million (3 106) times. Calculate the width of thecell surface membrane in tin (micrometres). Show your working.

Answer m(3)(c)State one function of each of the following components of the cell surface membrane.Carbohydrate ..Protein (2)(Total 8 marks)(Jan2003)7 (b) The proteins in the cell surface membranes of two cells (A and B) were stained usingdifferent coloured dyes. One cells membrane proteins were stained with a green dyeand the other cells membrane proteins with a red dye. The cells were then fused(merged together) to form one cell.The diagram below shows the distribution of the proteins in the cells before and afterfusion.

Use your knowledge of the properties of cell surface membranes to explain theseresults...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)