The important properties of animal cell mw.8kigncm* qv-9l *v1u. 7tgszvrxz5embranes are fluidity and permeability. Which molecule is responsible for ensuring the g8u7-.c9.zv 1s*qz xngmvrw*5kit lv membrane’s fluidity?

  Which statement correctly describes the ce-jajs*a 9r4w x4o +pxpll membrane structure?

  Which structure represents a component responsibf of .m85f- ky63u8.megwk/u6hv s jsfle for reducing membrane fluidite jmksf86f fh os/kuv5.wu.6-mg f3y8 y?

  Which component of the cell me)uart+dn ) qrsu4 8;ibmbrane is represented by structure X?

  Which of the following is not a funcw m576y va7t5cpkum2f tion of cholesterol in cell membranes?

  The diagram shows a pla8rtz r4tl 51eneris(:sma membrane. Which letter indicates cholesterol?

  Which of these membrane protehg t.xhi8j9u)f s 2fxbv 6s+c)ins carry out active transport?

Neuronal cells have special membrane properties that allow their axonu7w ksn4lkkz2bu 0 jpq;64 d/os to propagate action potential from one cell to another. The diagram below shows a lo4njsbk0d4qk 6 w kz u/p72;uportion 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 bea sspn98ti fh:8r (Ursus maritimus), which is native to the Arctic. Which statement about the composit8s :fn shpi98tion of its plasma membranes is correct?

  Which allows cells to stick tq 0eq *-v:phr6jr stu9ogether to form tissues?

  Some acetylcholine released by a monw)3 wyrvbyak l)95 *ttor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes w9*alvkw )yrbtn 5)3yare required for this to happen?

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

1.Outline the effect7a wr4 eu 4rt7hcajsb-p8x5s-s of placing 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 auk q6n7xt28 oe function of membrane proteins?

  Which of the structures below can tra(odie rq+f69t nsport water molecules across the cell membraqir(d f+t6o9e ne?

  Which statement describooyh5mv/ovfs 7 uir)(:vc2,gfk-j 4 bes endocytosis?

  In an investigation into the effect of solute concentration on diffus m8 vvh 2j+7vqu w0r(y-rj- j+vit,jpyion 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 8jtp7 +qj0vymy 2+jrvi-juh wv -r(v,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 resultjxb2;ogg9*n h0q gki-vj pi.2s of an experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue were immersed in different solutions of sucrose for 30 hg9kv*n-22iogx q b0 ip.j;hjg ours.



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 smal s;lgjp/0kzkkm.1 bz0bbir /*l intestine, an example of indirect active transpz1; r kpmi/gbsjkb lz.k0b/ 0*ort?

  Which type of transport is represented by this di gj/ /07c,*motvzwm nm5ag 7py3 7xusbagram?

  Which row about the different me)()1wnr amq1ys bgzn,dlm/( sthods of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson mmgw+;(iaus cw5 0o0h todel 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 cep :dtm5wl9,x.hp ( xnxll’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 studyfqqv-zavnadd1 1vb8)pd .i :/ on the percentage of cholesterol found in the cell membrane of epithelial skin cells of different anima)f :d8vd vv/z1a-b1idq np qa.ls.

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).