The important properties of animal cell m1pb r9mitr pl ,(g1s4vembranes are fluidity and permeability. Which molecule is responsible for ensuring th4 ,ptrvip9g1rlms (b1e membrane’s fluidity?

  Which statement correctly describes the cell membrane structur 6 u)fbuazl+m3o3 sb.ue?

  Which structure represents a component responsible for reducing memg+ 3r k(jvcqeo ,/ygx vtu7(h9brane fluidity? t u7kj(cqe+g /g9rh yx 3ov,v(

  Which component of the ce)oz b7lg :p0n:(a0h)gep j gmtll membrane is represented by structure X?

  Which of the following is not a function ofx 3b4rp)niks*s/kpkp3 kl0, x cholesterol in cell membranes?

  The diagram shows a plasmata,9/gw mpy 8tqq*q n6q2omdm/h uv37 membrane. Which letter indicates cholesterol?

  Which of these membrane prbve we., rk7u0h cj04goteins carry out active transport?

Neuronal cells have special membrane properties that allow their axons to propakptsw); ;ca oo9uf8k/ gate action potential from one cell to another. The diagram below shows a portion of an axona) ouk/sa;o tcf8k;w p9l 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 na 4wo;d7o x8q8pvx kx3o2fc mb8tive to the Arctic. Which statement about the composition of itsx7 pdwo88x 2k xq;oc fm3v8bo4 plasma membranes is correct?

  Which allows cells to stick together to form tissuesm/qyh*5jn ,li6 7pz( 0lmq zon?

  Some acetylcholine released by a motor neuron at the neuromusctef,s8ggw 1 c+ular junction stimulates muscle contraction, w 8tg,gs+1fecwhile 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 placivgf0m8a tk9xt 4+en5qv/+-n hgi2mv kng 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 fun7gmrd .+lf7-vigmt3 w /y/d 1 xcxuql2ction of membrane proteins?

  Which of the structu b vi4v9lolar6+7)rz.xlerw*res below can transport water molecules across the cell memb. bl7a+v i4)lxv*w z6rlo9rre rane?

  Which statement describes endocytosid4u-b ;6whnq,dqf j qqrr j 4oa(/2z2as?

  In an investigation into the effect of solute cohks1u1w5qd d2 ncentration on diffusion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane balloons. Each bal2kwsq5dhdu 11 loon 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 b *0-*tv:vb 0/ii7yuk:nudo.re vyfa experiment on osmosis in potato tissue (Solanum tuberosum), cactus /ruin*f7 vbebyo*y:.: -d kta0u0iv vtissue (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 c)ex+i)i9gceqzy 8b 9 in the small intestine, an example of indirect active t g+q8i)zcxb yc9e)9 eiransport?

  Which type of transport is represented b f3(h:uha yor;y this diagram?

  Which row about the different methods of membrane trans6c ,mqps 2gk-xport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasmfu,f hvlp.4jqy;x w ke2:z /0-ozm:vca 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.cy(zq 4o1vxl 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 from a study on the percentage of cholestee7j:h j7 oq(lwrol found in the cell membrane of epithelial skin7 hwjqo7e:lj( 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).