The important properties of animal cell memb cmn02i9sv:fhu(to ++exdb- y ranes are fluidity and permeability. Which molecule is responsible for ensuring the membrane’s fluixhvcf2m:0 synt+-+ 9(i bdou edity?

  Which statement correctly de dufj: m97ru 37i97khze fkbnq):v1dyscribes the cell membrane structure?

  Which structure represents a component responsible for reducing membrane flu2/v1hf -ohgrvziz .9+a6)govu yt /spidity?o/tvvp+6-g /y1 )u rozh gz2shif9 va.

  Which component of the cell membrane is representxl,o(fgw 409l 08aqcrsp6 ae eed by structure X?

  Which of the following is not a functckcks 1/ h1lt5o 0uc+jion of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicates cho9 zp2s cgxak2)lesterol?

  Which of these membrane proteins carry out active tran f-8q1y7ucla+a:1hf 1 lhwctisport?

Neuronal cells have special membrane 6 q)3d7nqk+v vrq4jx rproperties that allow their axons to propagate action potential from one cell to another. The diagrad r rq6+vv j43qk)q7xnm 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), w5.t*kn/x uyd8vn )pw thich is native to the Arctic. Whicn 5.kt*/y vx)8ndtu wph statement about the composition of its plasma membranes is correct?

  Which allows cells to stick +wff:x1j+ idq together to form tissues?

  Some acetylcholine released bz jlyo+-q 8y99jqpu h4y a motor neuron at the neuromuscular junction stimulates muscle contraction, wh luqjhz8 o9yj-pyq49 +ile the remainder is 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 placuk,-wxk 449*, mp8 hmbw+ rwzqx7auejing 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 no6jh1(c7v:u,gq d + ywhg juxq1t a function of membrane proteins?

  Which of the structures below can transport watebng,c fme i-51r molecules across the cell membran1nc-mf ,g5eibe?

  Which statement descr7y(kj .-qpz sz-jl4t aikg 3g*ibes endocytosis?

  In an investigation into the effect of solute concentratio:+w20qct)te eyny)a t n on diffusion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane balloons. Eacwe at)q)t nyy0ec2:+th 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 osmo)pg9jj*mi f4 lsis in potato tissue (Solanum tuberosum), cactus tissue (Carnegieapl)jmf* g4 ji9 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 pu 09xtgkp .5ij)*jinsodium-dependent glucose transporters in the small intestine, an example of indirect active transpkpin 59.t*pujj0xig) ort?

  Which type of transport is represeeo65;v2w j(ojfp: gvtnted by this diagram?

  Which row about the different methods of membg 7*oy *nf w2*x(bk1qlsyssg4 rane transport is incorrect?

  Which evidence supportvdxpm*rfkbtpl0p g. 92+iz 12ed the 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 thec;5yo q3q234a m:phwx atkcg : fluid mosaic model of 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 percentage4e*h ;qz t5aur of cholesterol found in the cell membrane of epithelial skin cells tu ze ah5r;*q4of 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).