The important properties of animal celmlx7a j hou , dc;r;h3j9;vclam,nj34 l membranes are fluidity and permeability. Which molecule is responsible for end3n4oac h3;,;;aj9 7jllxc m urv,m jhsuring the membrane’s fluidity?

  Which statement correctly describes the cellh/ rlbjypx;a 4 kui3+ pfi1n61 membrane structure?

  Which structure represents a component responsible fojmw (1 unxow*lw9tq)xk- 5 7llr reducing membrane fluiditlmwtoxl)- w5u1xk7( 9w * lnqjy?

  Which component of the cell membrane is represeg9hv5)z5* uc:(aff snk3ek g+x vze +snted by structure X?

  Which of the following is not a function of cholesterol in cell membrr/sxd) m m rhzkj ri06r/4akks k7e5l(8+ fpr1anes?

  The diagram shows a plasmbge6 3jmw). m/m)d vmea membrane. Which letter indicates cholesterol?

  Which of these membrane proteins carry out i;py-v qp6j) pjd 3; pa 90xn0e17wkrf3brjzd active transport?

Neuronal cells have special membrane propern3/ai k q7 x/nxx*i4yrties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axon7 r x/y/*xnqinxk3a4ial 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 maritic u. nmax55 gi iw1z.c8s7rvb(mus), which is native to the Arctic. Which statementwbx7mg18.5 iicn ru5cs(.z va about the composition of its plasma membranes is correct?

  Which allows cells to stick togil fxkp5+l* ;gether to form tissues?

  Some acetylcholine releaspef5z.fr*ly0i9)qakyyo* c , ed by a motor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from ,i q a90pfk*rf)yy ez.yloc* 5the 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 liqhat5(mp q q3)ver 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 membrane proteinse np(pwu2 4wb n(mwv2/?

  Which of the structures below can transport water mo-+mn98maw g ki6 bjv.rlecules across the cell membrane?.vmg j9abkw-+8in rm6

  Which statement describes endocytosis?1w6kbwaadl0 +x;dz ut7 9i+hxb d2 i+z

  In an investigation into + lfcn3tc 5xp;the effect of solute concentration on diffusion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane ba3clf t;+xpcn5lloons. 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 results of an experiment on osmosis in potato tissue (Solao w:o+qt(huz 5, 5iotinum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue werwi, +o(i:oz5 qt ou5the 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 in the small in+wmq:d3m v2qwj,6emm testine, an example of indirect active 3q6:mjvd2qm ,w w+emm transport?

  Which type of transport is represe lkla r-jt0;a4nted by this diagram?

  Which row about the different methods of membrja fyy*8g9g*c ane transport is incorrect?

  Which evidence supported the Singer-Nicolson model ofa4;m+em9m)tguc 0jxc/k: dlb 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 cell’s plasma me 9ote u(/;n1c7 au10pirna:szmsh1ni mbrane.

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 ty;o mmh 37qso 5ve(:ashe percentage of cholesterol found in the cell membrane of epithelial skin cells of ds3qo7s :oyh5; vmam( eifferent 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).