The important properties of animal cell membranes are fluidit 50grpc(c9xqhy and permeability. Which molecule is responsible for ensuring the membh q9 x5crp(cg0rane’s fluidity?

  Which statement correclo1aktw:3kp2)c-p2 m a o c6tctly describes the cell membrane structure?

  Which structure represents a component responsible for reducing mek-r)el hh+nn8ak s m:9mbrane fluidity? r-8hnmn)khk e+9asl :

  Which component of the cell me(d p2z jk4 m, 77rf6rb09l(jwk oncyzqmbrane is represented by structure X?

  Which of the following is not a fueo 8;uwdu jx4q1l /vsincv-,4nction of cholesterol in cell membranes?

  The diagram shows a plasma fwhi+q5 t dq);membrane. Which letter indicates cholesterol?

  Which of these membrane protein0hrhp nq7fnw8tl5k t;2hvrzc71o 4 1is carry out active transport?

Neuronal cells have special membrane properties that allq8(ey2kgx 7 r hs( *fi;vjnx*aow their axons to propagate action potential from( x*fyq ais7 2g( e*krnvh8jx; 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 native to thee*apf 9w d)x3 8tmny*l Arctic. Which statement about the composition of itmy9 lw xen3*)ap8*t dfs plasma membranes is correct?

  Which allows cells to s1 *jrssgfsb+47 ipx*+kkbmh1j0b/ g ktick together to form tissues?

  Some acetylcholine released by a motor neuron xc y4:/ :j rljyid;d5 6opymz,at the neuromuscular junction stimulates muscle contraction,:d,m y/ :ryjlic6 ;4opdzj5yx 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 placing a liver cell in a hypotonic solution. k0c6yeiw 3; az
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 mem-e c4bskh d m5+upxhyw(dih0n(ze2( +brane proteins?

  Which of the structures below can transport water molecules across the cell m4wncm,5iwc ym)q/tgr o 2ve42wzf;;zembranm4wznemzw cgr/foq ;,5vyw 4 )t2;ci2 e?

  Which statement describes endocytossvwng( lt u8m82iv**d9kr( 8pazjlf/((ytdo is?

  In an investigation into the effect of solute concentf ,5irwzpqd4 dm8z+x,ration 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 from the solution surrounding the membrane balloons in each beaker, placed on spotting tiles and test,+4f , z8drm widxq5zped 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 experikxc-y:m9 uakx l3tb85ment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sun8t5- kb : kuxl3y9cxamflower 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 transporte ,2cfv.ut*dha auy- ep3ugtxu*n 8 0d,j*spv+rs in the small intestine, an examp ,uav*-d ju8pu e fdy x*tps 3.*02ga,cutvhn+le of indirect active transport?

  Which type of transport is represented by thit5 ft5:uv2k (,m5mr.xvdq vams diagram?

  Which row about the different methods c(ix8 99 aacocof membrane transport is incorrect?

  Which evidence supported the Singer-Nicolh hb1sg,db1q0 son 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 -9r 5iy+lqbnz 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 resule3qrhx 77* limzv;or ,o*:uclts from a study on the percentage of cholesterol found in the cell membrane of epitheliaelom, v l;7qc h* 3:ru7izro*xl 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).