The important properties of antxu3t3*f4m:3a tl5z ma/f2g etjrwg 1imal cell membranes are fluidity and permeability. Which molecule is responsible for ensuring the membrane’s f5g4:x* tlt z 3et2w 1j33ufrg/aafmmtluidity?

  Which statement correctly describes the cell membrane structt+:b.(h1m6kxyhj eg g ure?

  Which structure represents a componen8j c7ks)e,*r9syr hl bt responsible for reducing membrane fluidity? ljc8ekh, ) rr*9ybs7s

  Which component of the cell membrane)vs l ,g tclvzvdn6e fv354m6zb)e/+ f is represented by structure X?

  Which of the following is not a function c ygcbxg9::pi/ bk1x9xjl)8 v of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which letteromjs /1u9 0m6ld y5j0dzvr;gt indicates cholesterol?

  Which of these membr6a fr wo:f oe.zx4g5.7p2fdrxane proteins carry out active transport?

Neuronal cells have special membrane properties thuy ckn v; 6e.+b;ani,cat allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal plauak,+y.i;c; nc6benv sma 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. nvsd;( k am7 tmlye9vh*4km/ar (Ursus maritimus), which is native to the Arctic. Which statement about the composition of its a.l4kh m ;ke(9mv*dsvtnmy/7plasma membranes is correct?

  Which allows cells toa0y:p bv cd* tmr4:j/j stick together to form tissues?

  Some acetylcholine re kw x4dm 9zcb2oyfyot2o-)x ,6leased by a motor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder 2)y4ktfo, cyobmwo2 -z69xd xis 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 1; 45edcqx umv: u t,wof,q6scplacing a liver 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 proteislvcs+ mux von l+o1fg8/tdd16 :yp*.ns?

  Which of the structures below can transport wate,n2 29 1rrzg9 avne7y;ktikpg r molecules across the cell membeigz9 7rrt,n2p ;kkyg 1va29nrane?

  Which statement describes endoqh wnnghfj7ze(y7uz-,t, t/7cytosis?

  In an investigation into the 7 v0.xuwn p3zteffect of solute concentration on diffusion rate, starch solutions, of varying concentu w7p. t3xnv0zrations, 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 results of an experiment on osmosis in potato tissue 0hg2 qtivd-unremz g3j+s)s)+h2 .cn (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar siec3r 0hm.hsn-2s+)g ti v2 ndj+qgz u)zed 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 in the sma4cghz;t b;ip:o) whc,ll intestine, an example of indirecich p;:z) g ,w;ctohb4t active transport?

  Which type of transport is represented by this diagkdkytfpmiw01c9 y.3: ram?

  Which row about the different methods of membrane transm rq281.d; nn0h- 8buyvmkdrw port is incorrect?

  Which evidence supported the Singer-- 7hon, 9nty(a:7l msejeiko .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 mo6f3s gu b,uv;7efqz 5idel 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 percent:il9hix /ot t,age of cholesterol found in the ceh,tx:iit9 / loll 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).