The important properties of animal cell lmrf:a.02p g dmembranes are fluidity and permeability. Which molecule is responsible for ensuring the membrane’s .:gpfamd 2rl0fluidity?

  Which statement correctla)x 9.vjpog:l up;t7*w3tdd, pm4znly describes the cell membrane structure?

  Which structure represeu,ix)x nboevb;l4.mmli3p. 9 nts a component responsible for reducing membrane fluidity? imxne,4. muolx39b.)b ipv; l

  Which component of the cell membrane is represented by s4b1 azc vgv/x/( vps n bg;j;0s9of, ymuj;g:ytructure X?

  Which of the following is not a functiono +w35vf wz3ferv:*js of cholesterol in cell membranes?

  The diagram shows a plasma meu:3*kdz8 dp2eu,o tso mbrane. Which letter indicates cholesterol?

  Which of these membrane proteins carry :26wsjweb2ozklo-1k w fv5x. out active transport?

Neuronal cells have special membranesj- xd 21nc j8rumd;f.vzvk18 properties that allow their axons to propagate a sn x8m8crddv;1fz-j2j vu1k.ction 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 polar bear (Ursus maritimus), which is nativq8 8p8;g 1kia y;x vfvnjc.ll.e to the Arctic. Which statement about the composition x k .8a fi1vpv;;8lgqjlcny8. of its plasma membranes is correct?

  Which allows cells to stick tow1k:6 urk.q +wsrgo,lo3 -q jcgether to form tissues?

  Some acetylcholine released by a motor neuron at the neuromuscular junction sc3y x6wi26.afm.pnae1 7k ms mtimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes are required for this to 6 .e6mnya7 p .12i3sfm kaxcwmhappen?

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

1.Outline the effects of placing a liver cell ink9ak(pthm:+i* 1 vjn a,o,gzs 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 membrane pro/)ab3 nw4cttj0w-qyw- e j5kb teins?

  Which of the structureso lamk1qc2;urig9 .s- below can transport water molecules across the cell membrai9o -2lc ;m.uqkr1gsane?

  Which statement describes ea;j dcnwe :5) cexc4-nndocytosis?

  In an investigation into the effect of solute cvh+k-bhlxa9; /dnjrl5h 3 +tioncentration on diffusion rate, starch solutions, of varying concentrations, were tin+ +9lr-l x a/;vhk3hbd5hjplaced 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 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 experimentuw)v2ta3ap4ow 43kt*q 1 *ib xjc sjh1 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 sucro2j34k3hs vacw)xbq*o*1t wpuijt4 1ase 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 transp y3 mhgrr* 60syirh9:ug b 9mq)uvo*s/orters in the small intestine, an example of indirect active tranmrhsvr*hg960/ygm y9 uqio*rsu b)3:sport?

  Which type of transport is represented by thc 0 :yhcmmil:2is diagram?

  Which row about the different methodh d -)sfpxd aiuj22y9813ccojs of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolso . lk,rl* +gtzb ezhmm5np51;e)l(b cfn 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 model of a cell’s plasma membrp h0* ao/- se/p/fvdxn5hxe,eane.

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 p;g mpcp7y2qm 9ercentage of cholesterol found in the cell membrane of epithegmpmy7p qc;29lial 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).