The important properties of animal cell membranes aupn7 fslp xyzk2*d .gnzh9b++i + b31tre fluidity and permeability. Whic*n+s7zh21d+pxzk lbf yu. pib n+39tgh molecule is responsible for ensuring the membrane’s fluidity?

  Which statement correctly des k7wg;gyf6di*66 tsxpcribes the cell membrane structure?

  Which structure represents xj, rzxxrv7ox/z) lh f5( p-)fa component responsible for reducing membrane fluiditj)rz rz,pxh/7f5 f(lo x -xx)vy?

  Which component of the cell membranir-ymr ncs18, e is represented by structure X?

  Which of the following is not a funct48bh5 qd 7q1s /pow e9rixsk2xion of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which lette(nk+vtg r0ta yct) 8vkw, 0*hhr indicates cholesterol?

  Which of these membrane proteins carxz4tn)srfr u:g;5 h1dry out active transport?

Neuronal cells have special membrane properties thd+:p8o op;rq0 y4b,yj4hzf nfat allow their axons to propagate action potential from one cell to another. The diagram below shows a porti8bpd+oy:n pfr, qfy;zo4 0h 4jon 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 en84um 4gz*gl Arctic. Which statemg48l zemn gu*4ent about the composition of its plasma membranes is correct?

  Which allows cells to spdt( kj jd:;ukrff:2w2f/kv . tick together to form tissues?

  Some acetylcholine released by a mot3 gv( lqfmy0gu*u;*gkor neuron at the neuromuscular junction stimulates muscle conk um;* y(fl*guv30ggqtraction, while 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 placing a lived0llq7t9c nh o cyw56c2t;ww0r 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 func:lyt/kp krn+hyx )y9 7tion of membrane proteins?

  Which of the structures below can transport water molecules across the cell mepapo 2(*-z fjce mc-7xmbranem fj(p -cxazep7-c2 *o?

  Which statement describes endocyedj5wejmcc) (v ;g /u2tosis?

  In an investigation inbghckrmql u5m eu p )x9991*m1to 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 9 )51 cbu9m ur1l*hxegmm qk9pof 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 rpcv3p sn, reu/ *d 7r*0e5ijtot81g 4w/rtmwfesults of an experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunf sdt*g pt ce 80ion mr/etpw/*134wfur57 r,jvlower 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 gn9kd1frka4ld (r ( 4sin the small intestine, kdf( (a9r1n grdl4s4kan example of indirect active transport?

  Which type of transport is represented by thi: z*z (zuyjo4ds diagram?

  Which row about the different methods of membrane transpormzgxe e:n cc2b2lsdl -41bm dfv7h:53t is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasm w tk.yt/sueq5)u+z)sic.sx 8kr6e7 ia 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 cellw-a 9, pw,vfwrb:1eqg’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 chg6rsyyq3r/:wkc1 :rym gq6f 0olesterol found inqy /y1rc :kwrmfs6rqg 360gy: the cell membrane of epithelial 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).