The important propertieseyraq3:h,3, g 5nb bmmue b1(v of animal cell membranes are fluidity and permeability. Which molecule is responsible for ensuring the membran3 uyq,bm3:(,e1 bb arhg v5emne’s fluidity?

  Which statement correctly describes the ceee7.g7c/fcdu a sj;m-ll membrane structure?

  Which structure represe9umqu a:a8ok5nts a component responsible for reducing membrane fluidity? :5qa8ou mk9au

  Which component of the cell mem ufa.z8 x.:xyy0p dr1ibrane is represented by structure X?

  Which of the following is not a function of cholefbeo7x6nwl*/ 1f (p rhsterol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicates chovcb 9x)pg: ddp+7m3s jlesterol?

  Which of these membrane proteins carry out active s5*ju2j,ez51c k /b2v pynww1 bcb3 attransport?

Neuronal cells have special mleil-ggk *it,wpw 2 +6embrane properties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal plasma -6llgtgpw+2 w , i*ikemembrane.

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 y.8buj g178y0gvtogjbear (Ursus maritimus), which is native to the Arctic. Which statement about the composyug8b. tjvj8yo 17gg0ition of its plasma membranes is correct?

  Which allows cells to stick together to form v9(n -uprdm j ,np2.ywgfj7b-tissues?

  Some acetylcholine released by a motor neurdg 1lirji0hj,16k ;oaon at the neuromuscular junction stimulates muscle contraction, while the remainder is 11 ,0i6 jio;jldghr akrapidly removed from the 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 lhvax* r e+.. rs7y owfnbn--h8-;cy aoiver cell in a 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 fufv0*sbq1g 8 zvnction of membrane proteins?

  Which of the structures 7* 16fyws w d9d2ni7 acso;ytfbelow can transport water molecules across the cell membrane fat;c79ys16wsd oy 7f d*w2ni?

  Which statement describes endocy c9tn7)1lwkpbq 3it k)ukhh**tosis?

  In an investigation into the effect of solute concentration on diffusion rate,05 k3lzfw/cj e 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 taken for a positive tzkjwec fl/ 350est 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 osmosis in poteqi5.u /jxmd uv* :4x6t p yc+qk )j2t)oig5vtato tissue (Solanum tuberosum), cactus tissue +6*.2)decijv5 y/iko:tgpquvx4 jq m5utt )x(Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized 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 sodium-dependent glucose transporters in the small intestt sv(r;fr-5-ma hpl;tn; +quyine,+5fm;(r;yq; t t- lrauvh-snp an example of indirect active transport?

  Which type of transport+e99dwd9.y6+.rmm osyrj0- foc ep w r is represented by this diagram?

  Which row about the different methods of membrane p + wcp( ptu-zfl2kcjb33 ,yo8transport is incorrect?

  Which evidence supported the Singer-Nicolson m;8 ;dm tnh,s u)8bb931qjihfxd .cl wcodel 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 fluid mosaic model of a celit 1g7q .6r(qug--yrm ig/ojhl’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 ch6v8.p h zgs wr,js*ao,t4x21i dg jvn1olesterol found in the cell membrane of epithelial skin cells ofjdgsvi o.6av1,1x8s wp, j*zr4 2ghnt 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).