The important properties of animal cell membranes are fluimn4, qv h g e77yrxb6te4juzvs1: *wr4dity and permeability. Which moleu14ex: jmqrn,w v6y 7b sgrztvh744*ecule is responsible for ensuring the membrane’s fluidity?

  Which statement correctly describb oz9k3d 4bn;rlo ,-c,u7 yazjes the cell membrane structure?

  Which structure repr 0(:fqzz oh6md pn j( fjx1ov3e+q06fqesents a component responsible for reducing membrane fluidity hjqd j61x0 (f:zqp(qov+foz fm3e6n0?

  Which component of the cell membrane is rep t2,ce8ds c r7:2wzmqzne)l c:resented by structure X?

  Which of the following is not a function of cholesterol in cell membrsz0b(5 hkqubsf 21 3a6kbr 0toanes?

  The diagram shows a plasma membrane. Which lx kwdfvl8pz f3sweb33v 4nezay.6v n7*c * r;3etter indicates cholesterol?

  Which of these membrane proteins carry out activep f (ej jc:./kja6s9t-+bbxdq transport?

Neuronal cells have special membrane iqefg3qsks,ursvja0k+4 ;- . properties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal+urs4s.;jqs kq k,f 3ev0-gia 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 vzepf 6zs q) )e(h:.2ibdyn h:polar bear (Ursus maritimus), which is native to the Arctic. Which statement about the composition of its plasma membranes is correchi q.))e(df6pb hs 2: z:yvnezt?

  Which allows cells to stick together to form nl ,m3br x)ihb.a3 ,ojtissues?

  Some acetylcholine released byhhn q wwe29, 19fsrey- a motor neuron at the neuromuscular junction stimulates 9eeqw,2 hfy9 -s 1rnhwmuscle contraction, 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 liver cell in a hkez1 vv0 10qmeypotonic 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 :b 9nza (ou8zhproteins?

  Which of the structures below can p2zjdtso ;ypg 390q60 oq. wsytransport water molecules across the cell membranq pp;09 3owyysgt 02.odzs6qj e?

  Which statement describ oa)mnx6 az 0:e( u5k1 4oxpz5rep6wvoes endocytosis?

  In an investigation into the effect of solute concentration on ,i*rv6a ,w orydiffusion rate, starch solutions, of vaa*ri,yr 6 v,owrying 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. 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 resul-2t gjb+ g9ohg0ew9wsbgz4 l1 ts of an experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sz2 wtgj glgos+e b9-94h1gw b0ized 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-den70: 27hth0 rt utdcurpendent glucose transporters in the small intestine, an example of indirect active tra d:tt0uruh2n770c trhnsport?

  Which type of transport is represented by tlqjpc*):ok6a his diagram?

  Which row about the different methods)rc+*r72i lgw u4d1.b u *ok0bfyr4qrh awe.j of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma membranmmqa 9z+f:t1-zc 3nage?
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 (h n8dn q+of.ftz kxv ;:+b e5vip.w (oselv7+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 pe+si+ pnp0*ocht2 b;horcentage of cholesterol found in the cell membrane of epithelial skin cells of different animal*op n20+ich+obth p s;s.

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).