The important properties agw7r jl7rh:ex pcv pbp) j4471x)jp;r7 om)nof animal cell membranes are fluidity and permeability. Which mole7p4c nl )7 p)g4rwxej7jm7)1:avp xr r bjhpo;cule is responsible for ensuring the membrane’s fluidity?

  Which statement correctly describes the8zci0e jqpf ueh21zf2/)y xr3 cell membrane structure?

  Which structure represents a rtfesiy :uh8gh8ao 2 .x5c:m* component responsible for reducing membrane fluidityix y2rf:to .u h*a5ehsg:8mc 8?

  Which component of the cellfn.75u47 f-p egnv/ gkp3o wer membrane is represented by structure X?

  Which of the following is not a function of cholesterol in cell mycntc1pju.d w417i h+embranes?

  The diagram shows a plasmzn7 coh;t4m )qa membrane. Which letter indicates cholesterol?

  Which of these membran8 4,4 vtcfbxipgno5h1e proteins carry out active transport?

Neuronal cells have specip )s own:uhq+4 )7fdjfal membrane properties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axo+f :o nud wshf7j)4q)pnal 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 po8; pkx8( v23x8goh vcwn) pfwnlar bear (Ursus maritimus), which is native to the Arctic. Which statement about the ck)gop8n vx vc(wp8wf 8h x2;n3omposition of its plasma membranes is correct?

  Which allows cells to stick together rcl s)a-xub;7to form tissues?

  Some acetylcholine released by a mvj age7aup 6d,*/x-rootor neuron at the neuromuscular junction stimulates muscle contraction, *6ox a-j7d,pe/gru va 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 3iwtd9as(it9t +2i06z p lznqhypotonic 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 :yl4pr97)wio5zyhks+ 0jy c nis not a function of membrane proteins?

  Which of the structures below can transport water molecules across the cf6 p/zx(mlydv /v q0f,ell membrane6 (fq/pdxl0yvz,m/vf?

  Which statement describes endocb5f rc:koef.2a 59d tvytosis?

  In an investigation into the effect of sk:9.un zbbc) polute concentration 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 teste9:k)n. bc ubzpd 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 dacv4o )yp ;m-; vbza3results of an experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tis yv ao4c;;p)dzmab- v3sue 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 glucos u v qv8r/a,4 +su.rlpo,8ncux9 9oamellr,3ie transporters in the small intestine, an example of indirect active tr, 9xa nllisorq,o 89r cuelv 8v4,/.+a3uu mpransport?

  Which type of transport is reprehozq fkl :;*;mkl68m e-:v hgmsented by this diagram?

  Which row about the different methods of membrane transport is incorrect -b4. xgz:ymny?

  Which evidence supported the Singer-Nicolson model of the pla01+pij * vxrfasma 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 fd4 7ptgopx;j*luid mosaic model 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 8 rqlf.c8u-4nltz +kcqa(*t j a study on the percentage of cholesterol found in the cell membrane of epithelial skin cells of different anil8tcj(.zln- c q+ ratfq84*ukmals.

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).