The important properties of animal cell membranes are fl*xslo7g ) jn-euidity and permeability. Which molecule is responsible for ensuring the membrane’s fluies n7*x-og )jldity?

  Which statement correctly describes the cell membrans42xz4,b / jaqjn8yure structure?

  Which structure represents a component responsible for reducing membrane fluidiivp9 pg735qhtty?htp 5qgv3p9 7i

  Which component of the cell me 3n)04 xv;sc qnl9b+koyo q8oqmbrane is represented by structure X?

  Which of the following is not a function of cholester7v:jdd:4xtgff (r /ecrpz1l :ol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicates ch0t h6 .hhr.5oowk1*ejrmsp0b olesterol?

  Which of these membrane protei5ga:dn) gm1xjtf oa 9.ns carry out active transport?

Neuronal cells have special membrane prope74tunr o whzv;s*9ul cs7f)cv j:j29 orties that allow their axons to propagate action potential from one cell to another. The diagram below shows;7 sch:c9vo u4vj)s*9lfzj 7n2to ruw a portion of an axonal plasma membrane.

1.1.State the role of a sodium-potassium pump in axon.
1.2.Describe the action of the sodium-potassium pump.
2.Distinguish between simple diffusion, facilitated diffusion and active transport.
3.Compare and contrast sodium-potassium pumps and potassium channels.

  The diagram shows a polar bear (Ursus maritimus), whi**ku3.gkf,0iaz l g pwcx.v ;tch is native to the Arctic. Which statement about the composition of itsiulg v3, 0*k;pkfwzg xca*..t plasma membranes is correct?

  Which allows cells to stick together t9ch eaos;bb0+ o form tissues?

  Some acetylcholine released by a motor neuron at (q6 lnib4bku) o1k)-iss mr 3kthe neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from thei3(-r )4 l6)1ubs kn simkkboq synapse. Which processes are required for this to happen?

  
Which structure on the above diagram corresponds to the molecule below?

1.Outline the effects of placing a liver cell in ad ) i;4 f5v2w5popkfocyc8st. hypotonic solution.
2.Outline how the fluidity of membranes allows materials to be taken into cells or to be released from cells.
3.Compare and contrast four types of membrane transport. Include an example of each.

  Which of the following is not a functionmxhy(:7apt7- pph b;em/lrm . of membrane proteins?

  Which of the structures below can transport water molecules acrogl/qw-+.or nnr o5jp/ss the cell membgo +rn -// .pjnlrqo5wrane?

  Which statement describecli 22 4e4kcb+cqstj2s endocytosis?

  In an investigation into the effect of solute conce)vb,i qbwlxqn,k0j 2tk71v ; vntration on diffusion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane balloons. Each balloon was put into a beaker of distilled water and at 3 minute intervals, samples were taken from the solution surrounding the membrane balloons in each beaker, placed on spotting tiles and tested for the presence of starch. The time)kt v,vkbj i;, 2vw0 xqnq17bl taken for a positive test to show was recorded for each trial.


The results are shown in the graph.

1.1.Identify the dependent and independent variable in this investigation.

1.2.State one variable, other than time of testing, that should be kept constant in this investigation to ensure the results are valid.

2.Describe a positive test for starch.

3.Explain why the method used in this study would not be appropriate for an investigation into the effects of solute concentration on active transport.

4.1.Samples taken from the 5% and 10% starch solution both tested positive for starch after 3 minutes. Suggest a way in which the experiment could be improved to provide a more accurate result.
The accuracy of the experiment could be improved by  ----待选择----increasingdecreasing  the frequency.

4.2.Predict the time taken for a positive starch test for a starch concentration of 3%.
A positive test for starch, at 3%, would take approximately    minutes.

5.Suggest modifications to the methodology that would make it suitable to investigate the effect of glucose concentration on the rate of diffusion.

  The graph shows the results of an experiment on osn4: ii:.mze3mzn9t 3nqik2 u cmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar i u9z mniickt n:3q3:42enm.zsized pieces of tissue were immersed in different solutions of sucrose for 30 hours.



1.Estimate the concentration of sucrose that is isotonic to the interior of the potato tissue.
The concentration of sucrose in the potato tissue is    mol dm$^{-3}$
2.Using the graph deduce, with a reason, the tissue that has the highest solute concentration.

3.Suggest one reason for the difference in internal solute concentration between the sunflower seed and cacti tissue.

4.The epidermis of the potato and cactus and the testa of the sunflowers seeds were removed. Suggest a reason for this.

5.Predict what the appearance of the cacti tissue would be like at 0.5 mol dm-3 sucrose solution.

6.1.State how percentage change in mass is calculated.

6.2.Explain why percentage change in mass is calculated rather than change in mass.

7.Explain why temperature has to be controlled in this study.

8.State one way in which this experiment could be made more reliable.

  How is the action of sodiu; 1mz.mh ircucdr8b0vjt-) ) rm-dependent glucose transporters in the small intestine, an example of )zv-h ijucc81 0tr;mm bdr.)rindirect active transport?

  Which type of transport is represenl*sa/ zfla 1*pted by this diagram?

  Which row about the different methods of membrane transport is incorrec3k8 gp15 -n 3wcmqbztvt?

  Which evidence suppor-cc t1h m)dxr;ted the Singer-Nicolson model of the plasma membrane?
I. Membrane fusion experiments revealed membrane proteins can diffuse from one position to another in the phospholipid bilayer.
II. Analysis of membrane proteins indicated that some surfaces of membrane proteins were hydrophobic.
III. Electron micrographs revealed the appearance of the membrane as two dark bands separated by a light band.

1.Draw and label the+ jfmt6e8wzif dq545m fluid mosaic model of a cell’s plasma membrane.

2.Distinguish between integral and peripheral proteins.

3.Compare and contrast the structure and function of glycoproteins and glycolipids in the plasma membrane.

The table shows the results from a study on the percentage of cholu ut* snw8*gc)esterol found in tc) n *twu8sg*uhe cell membrane of epithelial skin cells of different animals.

1.Calculate the mean percentage of cholesterol found in the cell membrane across all the animals listed in the table.
mean =__%
2.State one role of cholesterol in the cell membrane.
3.Suggest why arctic foxes have a greater mean percentage of cholesterol in their cell membranes than kangaroos.
4.Estimate, with a reason, the percentage of cholesterol that would be found in the cell membranes of polar bears.
5.Explain why the mass of cholesterol in the cell membranes is calculated as a percentage rather than a whole number.
6.Suggest why the cells studied may contain a higher percentage of cholesterol than shown in the table.
7.1Based on the data provided, suggest which animal in the study exhibits the highest fluidity in its epithelial skin cell membrane.
7.2Explain your answer to part (i).