The important properties of animal cell memlezozt3z/j /.9 zf+ jsbranes are fluidity and permeability. Wzzsz9/e3ljjf z.+t/ ohich molecule is responsible for ensuring the membrane’s fluidity?

  Which statement correctly describes the celljoe dt0e5-w p; membrane structure?

  Which structure represents a component responsible ljwou bnddr2*t8 94o* for reducing membrane fluidity? o 9*2 *dn wbj4ut8oldr

  Which component of the cell membrane is represent 5t(n+gftzoekcn/3 q ;ed by structure X?

  Which of the following is not a function of cmg+mt v9-2uhlholesterol in cell membranes?

  The diagram shows a plasma m c4xy(qg1qm1r embrane. Which letter indicates cholesterol?

  Which of these membrane proteins carry ouc4ibgb 1rrk39 t active transport?

Neuronal cells have special membrane propeo(j e;87dcgp erties that allow their axons to propagate ;eje(p 7oc8gdaction potential from one cell to another. The 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 bear (Ursus maritimus), which is native t1ffr3l/lghj 0x8 w( b e6wixe(o the Arctic. Which statement about thefexw w ehx(ig f081l(rjl 6b3/ composition of its plasma membranes is correct?

  Which allows cells to stick together to form ekpc,9/ i:+z em6w8bk m.h vn8pkhk u3tissues?

  Some acetylcholine released by a motor neuron at the neuromuscular juy quayi3;5/g znction stimulates muscle contraction, while the 3yyaz i5qgu ;/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 pla i:aj94yyzbwdi mlh(4t 1i ;o6cing 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 membrab578 -.rufsv,r ru qcqne proteins?

  Which of the structures below can transport water 74dpa :ej m(rcxw+f: 2lyy5 efmolecules across the cell membranef(:a 4 75cwjdeylep ym rf2x+:?

  Which statement describes ,bxdbhpom 3i 4p72 3 1aad:dofendocytosis?

  In an investigation into the effect of solute conch)).ske4oz bxs-u/f e :y8l *dlnxhmd 4w5l 0xentration 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 pr8fy ux4szh)n0ko b:d/ hx-ll5m* x4 see)wl d.esence 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 po1:pgo;r* 9arwm8zdi qtato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthgm o*a91: r zqr;wpd8ius annuus). Similar 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-dependent glucose transporters in the sma oyw sm. q64/mr:peado3a5wk 0ll intestine, an example of indirect pd:o /oq 3w6mwr .54aay0m skeactive transport?

  Which type of transport is eky t74;kiz q.)+e 2be+o 0tntrhy5ltrepresented by this diagram?

  Which row about the different methods of membrane transport is incojw((td m112k akmjcl3 rrect?

  Which evidence supported the Singer-Nicolson h cq*1le)a- aemodel 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 cell’s pla +ph0w/ wnj+o3ebldq8sma 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 fol )abw*z 6i-crom a study on the percentage of cholesterol found in the cell membrane of epoclw)bz-a6 i *ithelial 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).