The important properties of animal cell membrane 3e9uz5osn 5kb- rs1iss are fluidity and permeability. Which molecule is responsible for ensuriz5s1sn r u5o9 s-keib3ng the membrane’s fluidity?

  Which statement corre uep.gz*qgy 26a g8/uectly describes the cell membrane structure?

  Which structure represents a component responsible for reducing membrane 75t 4ojblpe77c rq4r+7gw oesfluidit4pc7e7 5w7beo7ro4sq+ t glrj y?

  Which component of the cell membrane is represented by stre5..6xn nw,vm b8rwq oy e,r,lucture X?

  Which of the following is not a function of cholestxccx hgh0a-+ 0erol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicates cholwy))bi1 2o8b8g m horresterol?

  Which of these membrane proteins carrzj(l y*+h 41fvokq4 y7jca o,qy out active transport?

Neuronal cells have special membrane properties that ++304j 2 c9gxq di-q4zuqej.ohyflqx allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal plauloji3f+24x xqzcd+.hqq 9q ej -y04gsma 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 rc,cl, (cj c/+beg.ov nv 4bql(tt4 w6the Arctic. Which statement about the composition of its plasma membran+( ccclbg bt(lv4 ,ej.o/6cw4tq r,vnes is correct?

  Which allows cells tyw4.f( 3hv ev aiey7l/o stick together to form tissues?

  Some acetylcholine released by a motor undf4+n-skz qd.1z+o neuron at the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from the n.dof-nz+d 4s k1qzu+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 pl,e 7s3sa8o3o4 wvwpe7 ,8lfgzowy) t bacing 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 ofgya67) kt;sna membrane proteins?

  Which of the structures below can transport water molecules across tj2 3(-zzsib+x0f ghn e.vrg v:he cell membrnsgvjv-3z h +(:xrbig0f.2z eane?

  Which statement describes e(x xe3 xz,d8racjx;t)mc 8d8 lndocytosis?

  In an investigation into txgs(6p5 7kj mv4dhhh9he effect of solute concentration on diffusion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane balloons. Each balvk5jh 7h(hdg 9sp x46mloon 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 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 osw7.g +0d 3jpbki lp7oyzkj( 4qo.hsi8 mosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue werqlhb.p jydz8 (i7 ik7w p .0+4j3ksogoe 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 dx jfo1 36onz3ywt8+u ++u qdof j,n.wglucose transporters in the small intestine, an example of indirect active traqt++6w wfnu dj.dxfou 8o z,y3o+nj31nsport?

  Which type of transport is representix;9 sblsqm /9lv ql54z q,3bmed by this diagram?

  Which row about the dif,q g8c wwcv+;nferent methods of membrane transport is incorrect?

  Which evidence supported the v0/5v m*hc,a poi ,ntpSinger-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 fluid mosaic modeaxg z369ro- o-cfl5l5e uqnx1l 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 ;ensvfipkkx b ;4d2tq(uz6 38from a study on the percentage of cholesterol found in the cell membrani 3kxdsnfub2;(ke46;vzp 8qt e 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).