The important properties of animal cell membranes are fluidity and permeabilitggqoy2eh -.6rq vvb -8y. Which mol6g q.2ve q-o8 ybv-rhgecule is responsible for ensuring the membrane’s fluidity?

  Which statement correctly describes the cell membrane s)f 6)0bcchay otructure?

  Which structure represents a component responsible for reducing membrane flui5zr zmj8bu/ *la5ej9gm*pk i5dity i mkezpm9jz*b 55a5lur8 jg/*?

  Which component of the cell membrane is representen8 je ps4ag*73-h wpw5eeklkgbp z*k;14 0bq qd by structure X?

  Which of the following is not a function of chola5e0q kujt+-,dr 1pgdesterol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicates choleny,e4 flzuln p;do,p3db; h1 yba(+s9sterol?

  Which of these membrane proteins carry out ac :,wfmn6hn1ff3(d tmltive transport?

Neuronal cells have special membrane properties that allow th*b b- edjwq;)ad.x u zcv12kc4eir axons to propagate action potential from one cell toc dba2d e*.4w;z vuqjx) 1-kcb 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 nati7b9v7vssk -t uhx 2fc8ve to the Arctic. Which statement about the composition of its plasma membranes is corrxtuc v2 fvsk7b8 -sh97ect?

  Which allows cells to stick together to form m)k3egas 6s;sgc my., tissues?

  Some acetylcholine releayvry,-waj,sh j9 lh -:-crvj7sed by a motor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder i7c :-y w, sayj hvrjvh9rj--,ls 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 plv/nu5a 9cdkf w,).bvdy 2,aeoacing 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 of membrane ptlo3,4 plnad 1roteins?

  Which of the structures below can transport water molecules across the cell mi p)233p e3yz)y wsx5krbod 8fembry38r5pw f2dzbp )ek) 3xo3yisane?

  Which statement describes enwms pm-w/v .2onckdur,g;3txs 1g7 w 3docytosis?

  In an investigation into the effect of solute concentraryjuh( d k0w hclha8+ kc++n8/lhj4)htion on diffusion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane ++h ll0rkah/8h(c jj k u8wc)+ hd4hynballoons. 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 experiment on osmosis in potato tissue (Solalh1-qavn tba8 ,v6*wanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized piec6 - vl a1wvthqba*,n8aes 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 ofl1ry :-w5pw1kpr8 lf8w (l kmc sodium-dependent glucose transporters in the small intestine, an example of indirect activ:f-(plr1wwcmlrk1 5yp8 kw8 l e transport?

  Which type of transport is represented lo xdd- ,3,trd1y2zovzh05g2n tze4o4e cz 4jby this diagram?

  Which row about the different methods of membrane transport ,k2 zfd;d;: 1:fl ch;j/fkonjmn7xyp is incorrect?

  Which evidence supported the Singer-Nicolson model of the 8 h:bodhzy(g+n-- swu 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 cell2qc)+4eoh b eh’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 h mno7yd izae 5.pt.6.from a study on the percentage of cholesterol found in the cell membrane of epi.ymiat .6phneod z.57thelial 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).