The important properties of animal cell membranes are yf nf:fcy3gff/ )84fe fluidity and permeability. Which molfc8/f:f 3 nfyye)4f fgecule is responsible for ensuring the membrane’s fluidity?

  Which statement correctly describes the celg(.2p)6you )mmyz o6bvbocp:prxt6: l membrane structure?

  Which structure represents a component resp7dpc9m*n c b54k)nm0.ny ppx 7;y yqbvonsible for reducing membrane fluiditcy ; 0 n4k7xby yp75n*mcp. )bpqn9vmdy?

  Which component of the cell membu8 /y8+rolzlrm2dc,m rane is represented by structure X?

  Which of the followinaw6(0 tvrl :bpr6 mvnem)gjeg 0m0(;q g is not a function of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Wpe8ecj)2g7t-hart-r-jv6 o l hich letter indicates cholesterol?

  Which of these membrane proteins carry out active tr:mts:(15cq98jwmcje(ixqx 4jb d g +z ansport?

Neuronal cells have spec22wggc;szaga:dt s g,7)8n g bf0f-liial membrane properties that allow their axons to propaga 0gi8bgfg,2zw a)gd:-t f; s l2cn7gsate action potential from 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 the Arct::0xl)zdso u3lo f/biic. Which statement aboud0 3s/lx:i zofuo: l)bt the composition of its plasma membranes is correct?

  Which allows cells to stick togethe f--u9p nwzv n06rstb xa-y(h3r to form tissues?

  Some acetylcholine released by a motor neuron 9:friib9 ..2s kivraickm)4cat the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which pro4). rvifa9srm 9ci:k kic i2b.cesses are required for this to happen?

  
Which structure on the above diagram corresponds to the molecule below?

1.Outline the effects of placing a lrdhailku j l3b)f/8 )7iver 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 me( ,*d nz 2gvdiba3:jngmbrane proteins?

  Which of the structures below can transport water molecules across the cell u vks2hd;.1 z;wcrws;membrhw1;dk;.;su s 2vwcz rane?

  Which statement describes x l*,4 zxj s0rte8lkvy5h f4f3endocytosis?

  In an investigation iy1).wwhgl d7ed9b 9kd/ 6ardnnto the effect of solute 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 tested for the presence of starch. The time taken for a positive test to show was recorded for each trial. hn96b .ddd1adw e yl)rg7k9w/


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 r.zlme.e6 mos s+yec+d vl(; n+e u: as4ip5e/wesults of an experiment on osmosis in potato tissue (Solanum tuberosum), ;4/(+n5vpeay: + desl+ ..u6zm wlio ces mseecactus tissue (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 in the small intestinv;8wvprgv 4*sg ; ,drze, an example of indirect active trans;z4gdr, s8vvg*; rwpvport?

  Which type of transport irq e et/6b.xl6s represented by this diagram?

  Which row about the different methods of membra a ;20q9zskifwne transport is incorrect?

  Which evidence supported the Singer-Nicolson 08yjq.qkiwnl,/le6tq vn 7n4model 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 p/p xv n-ux8;ymd2 fh4of 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 chona8iuvvl70 r- lesterol found in the cell membrane of epithelial skin cells of differel7i0n uvra-v8 nt 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).