The important properties of animal cell membryy.e1y0 l,fjhhlbs6 5anes are fluidity and permeability. Which molecule is responsible for ensuring the m eyj 5sfb 0hhyl.y1l6,embrane’s fluidity?

  Which statement correctly descq0va gy s/ g2e3do -mic8pzb*,ribes the cell membrane structure?

  Which structure represents a component responsible f)xb.fugr7v3 fy aor+ *or reducing membrane fluidity? yaf 3vru*)xb ro7+f. g

  Which component of trxuxem56)3+1 l y dz0il(pirshe cell membrane is represented by structure X?

  Which of the following 9(i jg2l9inns is not a function of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicates cholestj. * cdxq1xip k/o:v8jl.zpj yd99jb6erol?

  Which of these membrane proteins carry out active tran)-ky -*or a;wabx7 evlsport?

Neuronal cells have special membrane paj,amr91d;yoo 1je7rg f26g groperties that allow their axons to propagate action potential from one cerg19yaj1j2 r,mo;d o afg6g 7ell 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 polal34dm(l53xh pl) u fsyr bear (Ursus maritimus), which is native to the Arctic. Which3x y3hl 4ld(slumfp)5 statement about the composition of its plasma membranes is correct?

  Which allows cells to stick tog1qbx, -ysz0oyether to form tissues?

  Some acetylcholine released by a motor neuron p; tirw/8 :nk ;prrg4yat the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from tp/: kn8yrg;;trri4pw he 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 hypoton3 d+y uvpgu:h2 5qqx lvj++q-bic 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 protei az2 zb9yem5:nf:k 8)2pvthkm ns?

  Which of the structures below can transport water molecules across the cell membim q(ync*4kosp x,oc/8: 3m otrane,3mtoys:xn(8 kcp4i cqm/oo*?

  Which statement describes endk5y82ax *nm: sf ,xolbocytosis?

  In an investigation into the effect of so .ok lit774;bv.l ekyve cn ;k6rm-y1olute 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 testv y yk rlo;17lnve6-b ckim ;7o4e.t.ked 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 b5lrl5cxbv7ma:2o: i potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue were immersed in different solutions ofv5mc5: iob r a2:7bllx 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 thz: -w rl0h6do-m7tjbj e small intestine, an e-:wz b -7h0modt6jl jrxample of indirect active transport?

  Which type of transport is represented by this u dd/v( ii m jd/jsyyv4t1p1zhz;9n44diagram?

  Which row about the different methods of membrane xdu ln j 4eph:xi,ko:7/6rr1ktransport is incorrect?

  Which evidence supported tcti:gd3- 1yd mm/n bm:he Singer-Nicolson model 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 cev1 .kzfx ag**2hm p)xlkiv14jll’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.g tiw8 2 zvfouu*sy(zi75yj- of cholesterol found in the cell membrane of epithelial sy o7.(uywjt 82*z giuz v-sif5kin 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).