The important properties of animal cell membri4i)je*e sp5 panes are fluidity and permeability. Which molecule is responsiblp4ej)i5 p e*sie for ensuring the membrane’s fluidity?

  Which statement corre 9j q;k k++-do+ram kej*.kzloctly describes the cell membrane structure?

  Which structure represeny,vsf)nbs40z 0ow ay: )9pbjd ts a component responsible for reducing membrane fluiditnbbpv0 :o9w0z) ,sf jsa)dyy4 y?

  Which component of the cell membrane is represenb :1o)22eee:57z figl r giiheted by structure X?

  Which of the following is not a function of cholesteroawx8j5kj:3b1hwjo v/ l in cell membranes?

  The diagram shows a plasma membrane. 6i2bnq15 z8t/st mdiuWhich letter indicates cholesterol?

  Which of these membrane proteins carry outag +hu6 wi85wvrl* ;dy bs27ltl)q3dli8z o2g active transport?

Neuronal cells have special membrane properties that allow their axons to pr1q h iw x-p)10fwi:imgopagate actiow1-p iqw0fx)g:h imi1n potential from one cell to another. The diagram below shows 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 +w p gbb88dm/et 1max7polar bear (Ursus maritimus), which is native to the Arctic. Which statement about the composition of its plasm b8p8+xeg 1wm tdb7m/aa membranes is correct?

  Which allows cells to stick 2j b+jk bks cwhd 5k0g* e/5kk2ski)7ytogether to form tissues?

  Some acetylcholine released by a motor neuron at the neuromusculatxm5h6e /bai r.*vlx8b(t xo8r junction stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes are required b(/*8 tmxt6eoax .8r5lxh i bvfor this to happen?

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

1.Outline the effects of placing a liver celfj e29 ljct3,wl 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 funct;a53 taisxh9 sion of membrane proteins?

  Which of the structures below can tra3im )lys 3a no;(jvmls/;2yrr nsport water molecules across the cell membo 3 n)mr (msvy2;ra j3/si;llyrane?

  Which statement describes endou se-4kijk:py b-:ngk a 7r49we 16rqj1:mqopcytosis?

  In an investigation into the effect of solute concentratmfkr g 3i4f rgv-ucf*,;:v ok0ion 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 frok ior,cr3uf f:g vfg4;-0mvk*m 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 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 experiq0goh(znc y +x7 k:ob*ment on osmosis 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 sucrose for 30 cbq y7:xo*+h g(nz0 kohours.



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 gl-zf7lu w8 g(ciysgx/ )6 qemi+ucose transporters in the small intestine, an example of indirect actfz- )meigwq iu7l+ x/8sg cy6(ive transport?

  Which type of transport is represented by th5tb*y c mw3flqy20sf8is diagram?

  Which row about the different me3(doh9:vokksw9d; kns q r id:vd3+;dthods of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma membg9s2h zbm 1*ylrane?
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 c*s*.ik yvt l6aell’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 cholesterol xwu/bmu, 5 (-ig yz3auwj5*b tfound in the cell membrane of epithelial skin cellstb,mxa y uwiu5(jz- *gw53ub/ 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).