The important propertiesk z1+j.wk z+(1 wu2biyff lhaesb);. x of animal cell membranes are fluidity and permeability. Which molecule is l w+bf(x k wey.1bzia)juhf+k2;sz1.responsible for ensuring the membrane’s fluidity?

  Which statement correctly desz)vbhuw o 249hd kaur:m-0xdu*((ian cribes the cell membrane structure?

  Which structure represents a component responsible fomtuah2ub ne 5vg79d 1.r reducing membrane fluidity? b2dhtun9 g5uav7m1 e.

  Which component of the c)ib21unvnim r)+gv 8k 5p5pdnell membrane is represented by structure X?

  Which of the following is n :qlvh+djxt- 2/t ,br q8a(j3lnjbvs 3ot a function of cholesterol in cell membranes?

  The diagram shows a plasma me;3)wynz dsi7g.u7 ci rmbrane. Which letter indicates cholesterol?

  Which of these membrane8yeio :i2wf (wnq8)t x ki36hu proteins carry out active transport?

Neuronal cells have special membrane properties that allow their axons tovp 18 rf4nultdz usret,9h(*2 propagate action potential from one cell to another. The diagu2us9evn ( t, rp1fdlhrtz8 *4ram 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 bear (Ursus maritimus), which is nllhj 8s3w zee,ve;c4f-5l e v3ative to the Arctic. Which statement a ,; 3e4sfvec 5 l8hwlevlj3-ezbout the composition of its plasma membranes is correct?

  Which allows cells to stick together tq6fzf3 /f,r5 klpne) xo form tissues?

  Some acetylcholine released by a motor neurgmu1+h*,h p yoon at the neuromuscular junction stimulates muscle contraction, whiyp+o,ghhmu1 * le 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 live2a hd8wvlleh3, xpl/2 r 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 followinum:9mtx+-jq5n gcrx7 g is not a function of membrane proteins?

  Which of the structures below can transport water molecule y;0qa 0b m(3t,gdgmoxs across the cell membrgbgmm0 yaodt( ;x0q,3 ane?

  Which statement describes kn t:ngrerbr( 1),.zbs+,-a l8nggk b endocytosis?

  In an investigation into the effect of solute concentration on dif.v4tgh, mn-lt5o16rz3kox ym fusion rate, starch solut y t6 o3rhmv5gn4k 1ml,z.t-xoions, 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. 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 experimul qq-- t0 ;xg vwmkq/97wu3zfent on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Simmu3 v;/kl gqquz9--wq w tx7f0ilar 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- zo c5gm-:g)rtcw-x8t70 ljbt5 mmw d6dependent glucose transporters in the small intestine, an exam55wt-g0tbl cm-w d7 rxz jmm8o:t6c)gple of indirect active transport?

  Which type of transport is represented by this diagram?pzi c0;k:tp:3 c0f.+mflxgzd

  Which row about the different mf3hdal(-hx sfhl0i)) ethods of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma membranex *v8 s u7cpjj5v6zn:g?
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 membrane.a1n x0,;a+isd.f0r u jkkw g(c

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 3b 59t sboo(qlaq(v,fthe percentage of cholesterol found in the cell membrane of epithelial skinsolv 3 q(o(t5b9b a,qf 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).