The important properties of animal cell . ar do* we*88s;lgdtamembranes are fluidity and permeability. Which molecule is responsible for ensurieal ;8*ddar.*g 8s otwng the membrane’s fluidity?

  Which statement correctl tp uazdj4(fptu+5m(3y describes the cell membrane structure?

  Which structure represents a component responsible for reducing mftep(0n/ 891w7ghyin3 0jey uj3 vf zpembrane fluidit(8pzj9yfv0 ge n/ jht10i73wey3uf npy?

  Which component of the cell membkw a r17nihv dt*4vx4jj(yn3:rane is represented by structure X?

  Which of the following is not a function of cholesterol in cell membranepm n.-xr(ghqlv,nryua w e*s4ftt14 b.6 nu)7 s?

  The diagram shows a plasma membran1voa:9 bgku/n5z ru u/e. Which letter indicates cholesterol?

  Which of these membrane proteins carry out actizz4vydj i.5 t)ve transport?

Neuronal cells have spe6 mp75.zt(2bn r gds3xa-f pbmcial membrane properties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an 3pgf szpx( nt2b5b .-67mrdmaaxonal 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 be2hc8tub;clz1 ar (Ursus maritimus), which is native to the Arctic. Which statement about2 zctc81 hub;l the composition of its plasma membranes is correct?

  Which allows cells to stick together to flb 9x pb1m+rtp7sq fg:q342ok orm tissues?

  Some acetylcholine released by a moqfah, 7(frx 5etor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder i 7x a,hferfq5(s 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 placing a liver cell in a hypot; oz1o0(ygulfav b :4v,q 3dytonic 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 ismr:t4 cr)-/c qgi )dqim mvz ;zxn8t2; not a function of membrane proteins?

  Which of the structures below can transport water molecules across the cell memb(x w/ubvgyj(9qjj9z 7raneb7w(g9qu 9zvj(/ xjjy?

  Which statement describes endh*lg g4o f2vgfp9*j(cocytosis?

  In an investigation into the effect yiq zpi;5f 4)rof solute concentration on diffusion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane balloons. Each balloon was ; qi4rip yf)z5put 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 o eb9ey*;jyb2n f an experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of *;y beje2b 9nytissue 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 sodium6 :;m( nkybg k3-im-wmqv8 hpx-dependent glucose transporters in the small intestine, an example of indirect active transport?kwvx:bh-8k(mpm6q i-mn;g y 3

  Which type of transport is represented by 0 hnpso9.s ,eh ec(f9nthis diagram?

  Which row about the dif-.txb*8x y (pw my 2h,sz:kya2p6kygsferent methods of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma memk7 uo0xsv**9 nf9hu (s5vt 5llfp9 relbrane?
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 cel-bkn5ocy+6 lkibm t83l’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)yj;sjxqf:7*i 6 uqbw pi ol28 from a study on the percentage of cholesterol found in the cell membrane of epit7jb6i wofq ix2 sj8q;yp:*l)u helial skin 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).