The important properties2d(fb18r nss,5 hcp/ ner ,mqzhdd20 m of animal cell membranes are fluidity and permeability. Which molecule is res,b(zdfnehnr 5 /01qmd22dmr , ps8chsponsible for ensuring the membrane’s fluidity?

  Which statement correctly describes the cell mem-opsdo xr;nf.z 3iaw anqs(4nf3* v)yoyv)),brane structure?

  Which structure represents a component responsible for reducing membrane fluiv wwv3r. 7iahlooe)( zx7x1:g dity? v) i1g.3 l ox:zeoa7w vrxw(7h

  Which component of the ceak8v xap 3p32d 4mi6dbll membrane is represented by structure X?

  Which of the following is not a function of cholesterol in cell membr hyk,u/,gua r8anes?

  The diagram shows a plasma membrane. Which letter e7;/ilkm7vu tanhdgb a).)*e indicates cholesterol?

  Which of these membrf)pi 4mpzr c2:ane proteins carry out active transport?

Neuronal cells have special membrane properties that allow/n. 7gwim c3s 9krn1oy their axons to propagate action potential from one cell to another. T/nn39gkw cmo s17 ryi.he 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 polar be sgf53vgww8565 uc veaar (Ursus maritimus), which is native to the Arctic. Which stauvve5scw wg58g5a3 6 ftement about the composition of its plasma membranes is correct?

  Which allows cells to stick together to form tissujupjyh5)) e( ces?

  Some acetylcholine released by a motor neuron at the n-mk0 s.hws8l+pe6d(kv8kv x)ll1ysm euromuscular junction stimulates muscle contraction, whilhk8l6 ks0p 1+vl8k dsvxmyle- m.(sw)e 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 liver95uhmk/ dn( kme,p-az 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 function of memxv2) s vj7g+0uoyc; c.bel: albrane proteins?

  Which of the structures below can transport water molecules acrg( ;ibp4p j- mgzh0/bkoss the cell membr bmjp bg-(p ihzg0/k;4ane?

  Which statement describes endocl)8) fokokn*g ytosis?

  In an investigation into the effect of solute concenj ev(xp)q6-.a*sbfv t ghuuv. 2dn..ttration 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 tested for the presence of starch. Teqju* tt. (d v-f.2.ngv) .hvsxbpa 6uhe 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 2vw lr a-g4ijj(;bt7 w;q zmy-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 sucrosemzw jtq-; 7iwga4vjb2 rl(y-; 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 glucuf1-3 9q6 pu5x i/hc qh cf-zlqdcb2qmhh 3p(8ose transporters in the small intestine, an elhbm qu fh-9 2pi/5xcc qz 18ph63qfc-ud3(hqxample of indirect active transport?

  Which type of transport is represented by this diagram? ijjb,pg)q05 3)dtfjjm4b js.7n-ky h

  Which row about the different methods of membrane trzer.eim :q. :fzf 7i uo-upe0k/p* op)ansport is incorrect?

  Which evidence suppo2ve fqa, kq+t)rted 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 the fluid mosaic model of a c 8v/ mfsn*0l9 pchzg,fell’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 studywl)-nh. b/:p,nws l iu on the percentage of cholesterol found in the cell membra :n- ilwh )/wunp.b,slne 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).