The important properties of animal cell membranes are02xygwww6) j k-p2s vi fluidity and permeability. Which molecule is kv 0 -xw2i6s)j2pwywg responsible for ensuring the membrane’s fluidity?

  Which statement correctly describes the cell sns5m2.x vk eq7/b5 fura2 )uz-bs+ch membrane structure?

  Which structure represents a component responsible for red6 w1itq0 v,gkuaxox66ayoc- 1ucing membrane fluidity?6q y x6oaikgu,v611wo caxt0-

  Which component of the celj3 ;dnp7f c5 yqd-qm0jl membrane is represented by structure X?

  Which of the following is not a function of cholesterol in cell me gdwg jm:(e;e:atz+ :kmbranes?

  The diagram shows a plasma membrane/ uqzsh6 w0mr3. Which letter indicates cholesterol?

  Which of these membrane proteins carry out ac 8ml 1,:nt wgg,m3dyczzl*+qhtive transport?

Neuronal cells have special membrane properties that all0uku o,(oaxf cp(ucqp x4ma*dq3 0,e,ow their axons to propagate action potential from(x ukoxum,34 (e0f,oc pp0,acqa *qu d 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 jx h5nfbr+ z.1jsira(8kt/r8 is native to the Arctic. Which statement about t/san +tz8 xk1rfjj.irh 58( brhe composition of its plasma membranes is correct?

  Which allows cells to stick together to fof: uaic :em(b+e49ambrm tissues?

  Some acetylcholine rele0;ic+ t t(.ugzcew:zaased by a motor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes are required for +zzg t(u:.a;iw tcce0 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 hypot,ujgz/gn +t7q onic 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 fuzcj8..ae5j xwnction of membrane proteins?

  Which of the structures below ca(pl4coksaa5 v):lt s(m -1pff n transport water molecules across the cell membran fa k4 :ol(st(sapfplc 5)mv1-e?

  Which statement describes end hjl8edd 0./cdocytosis?

  In an investigation into the effect of solute concentration on d. cmmv/wcwi( 3;q vovjo0,u v1iffusion 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 surrounw1c3. vcju0iq, m;mvv (w/v ooding 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 (Solan** w/z rqg43hsw29 0njwxgn hpum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissuegs*/nw 3wn9x p*gz0w4rjqhh 2 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 sodixxx17t3c95 v uqbvf89 1hm coaum-dependent glucose transporters in the small intestine, an example of indirect act957x89qafb1 tmxh cx voc13uvive transport?

  Which type of transposp /9vni)oxpd n) 7 60jfevgj9rt is represented by this diagram?

  Which row about the different methods-pc*f,8)dfm6agy:c/du d qaidft y2, of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasg9 y9 - dex)s/zlcb2zvwf7nn9ma 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 plasmar2qx7,jp ;r8vphcvi b 7a cd96 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 resup :l)ifc.*0b f- dgdzslts from a study on the percentage of cholesterol found in the cell membrane of epithelial skin cells of diffe .sl0 -cgi )p*dffb:zdrent 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).