The important properties ofk * (zo+qyl js4w8byw-ywqj* ( animal cell membranes are fluidity and permeability. Which molecule is respon w+wbk-ysj*lj wzoq(*8qy(y4 sible for ensuring the membrane’s fluidity?

  Which statement correctly describes the cell membry 3dh1m (fas9hpa/no0 ane structure?

  Which structure represents a component responsible for reducing mek.c7ya eh; en7mbrane fluidity;. enhk7ca7ye?

  Which component of the cell membrans)ohu5uc-ln: /vo b .fen0y( ae is represented by structure X?

  Which of the following is not a functi e a,oabit2i2+on of cholesterol in cell membranes?

  The diagram shows a plasma mefusf10)h n )xbmbrane. Which letter indicates cholesterol?

  Which of these membrane proteiqhsf 2, m+( s )pzewjeq)f5c6zns carry out active transport?

Neuronal cells have special membrane properties that allsr3w l hg2zyswfy+/6/ow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonawl 3y//g2srsw yh6z+fl 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 nativ+5s ) hzr)yf;jp:0tx1gcc0n :aroqxme to the Arctic. Whm5+g1 j )0 c;pfaxzr n0yq scr)otxh::ich statement about the composition of its plasma membranes is correct?

  Which allows cells to sticky (l9x gia .fqnt0ov (8z,/u,dhlffp9 together to form tissues?

  Some acetylcholine released by a motor ne,;/8sjqzm 94 mzwhbg 7pxuo 9muron at the neuromuscular junction stimulates muscle con9bs89hqxg m47/ z w;mmuz o,pjtraction, while the remainder is rapidly 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 piy.ty 2c siw(s// 6vjjlacing a liver 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 function of memq ) b)o 1my-xeoay-+pobrane proteins?

  Which of the structures -i y*okwo q/34ifpk3 bs; rkhsu*x.i8below can transport water molecules across the cell membr* 8rpobhi34yiu3-f kx/s*swk ;i.k oqane?

  Which statement describ1/jhnel gxbp7l1++b6-y9 osgu qthe9 es endocytosis?

  In an investigation into the effect of solute concentration ongpi2(n a zjm (,j8l+n eh.xad) 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 stpxa+ i(jd,l ).h8n(n2jema zgarch. 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 osmosi ia-j-zt:z 9.r; ng,juuh+zg is in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigzrt-hjii +,n9 zuj. -z:g;augantea) 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-dependentghj02xs p07qy glucose transporters in the small intestine, an example of indirect active transpo0x07pq hj ys2grt?

  Which type of transport is repre7t( d xv2zj;sfgkt1- . hhf:ofsented by this diagram?

  Which row about the different methods of membrane transport is in run*bh -0fqj,f41 yoakes ,5vcorrect?

  Which evidence supported the Singer-Nicolson model of the pla kjeyl*y,* xonu37c; qsma 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 cell’s plasma ( 4nn51mu.-t ;gktm6)agkw r :mem nafmembrane.

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 frqi59v+ wd8t aaom a study on the percentage of cholesterol found in the cell membrane of epithelial skin cells of different animals. ad859v qw+ti a

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).