The important properties of animal cell membranes are flu;xi kak+d*+1kd e1xdilt pgc g: ,a6p;idity and permeability. Which molecule is responsible for ensuring the mea i6 tglxx,ddkk+ ;ck;1*pd1aie+gp:mbrane’s fluidity?

  Which statement correctly describes the cel99p1eisd:l9ca 3d z).f eih gml membrane structure?

  Which structure represents a component respons)nkoa8;zjss 6 1dd 9x lsax7a;ible for reducing membrane fluidit8od za7;k91dss 6na; ja)xlsx y?

  Which component of the .i72: nwp9flbezqt p9cell membrane is represented by structure X?

  Which of the following is not a function of cholesterol in cell meb:qkua0h90w 2kqjot;d.v ac7mbranes?

  The diagram shows a plasma membrane. Which lej2:ao 4+wibgttter indicates cholesterol?

  Which of these membrane proteins2 bel w)1 ma nx(dlbges:/miiq2289rg carry out active transport?

Neuronal cells have special n.cdpg ll:)rm1* vnw1 membrane properties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion o11gmr.dwnl:vlp)n * cf 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), which is native to the e*szj21ey-mpdp +(hm Arctic. Which spj2 m y-z1*(smdh+epetatement about the composition of its plasma membranes is correct?

  Which allows cells to stick tomdj)n*vz k1 i+xz50 ixnp u1o:gether to form tissues?

  Some acetylcholine released by a motor neuron at the neuromuscular juncxg ru womz5 o+q.4zr:6tion stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes are required for this to happen?6xz u.4or:+q 5ogmwz r

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

1.Outline the effects of placing a liver cell in a hypotonic solution.jg1rq: 6ibm2 b:sumz 5
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 function of membrane xar+ :mzkt.: cgm v5xl(ak/(pproteins?

  Which of the structures below can transport water molecules across tho.r:lu 1vtd*de cell membra d.drult1*ov:ne?

  Which statement describes endocyto.,cfg (2c 3 vx5l-ffty e8sfs6ju7ovf sis?

  In an investigation into the eftsvxc* :biy.bi5 +6./ hr) lrtn7tx trfect of solute concentration 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 .cx/ ) t rtb:*6l xb.s+t int7rihvr5ysurrounding the membrane balloons in each beaker, placed on spotting tiles and tested for the presence of starch. The time 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 .md2hay 5qcgpp79z b6xt x6( dosmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue were immersed in different solutions of sucrot(6h .m9zpdc qpay6 7d5 x2bgxse 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 sodium-depen:clb lyhi hq9z dkt37 ,35bid(dent glucose transporters in the small intestinetkbi,dh7z cql:bdi 95(3hl y3, an example of indirect active transport?

  Which type of transport is representer) o.4kt ign 6whm5pv4d by this diagram?

  Which row about the different methods of membrane transport is /cr3 yovt w,lbum9c0f22re u3incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma rg.m1e9 -qf;w m5s oqvmembrane?
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 fluid mosai ihgxl,s65wnq5c-1ajq9 n d*e c 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 choleiftopzw1a.kh7 0s5 c n w-0w0z stob2*xl.(clsterol found in the cec0bc.wz 0( xs1hspw w2t.lz*0ol -if7 nk5taoll 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).