The important properties /3a8o d,7-wt u4adgq y/rjd jtof animal cell membranes are fluidity and permeability. Which molecudoa,dgt /4t3ya /8wq7djj ur -le is responsible for ensuring the membrane’s fluidity?

  Which statement correctly describes the cell membrane structurev a7;4pmucl p2?

  Which structure represents a component responsible for reduci2xfqpt olv7 c/9 qk(k3ng membrane fluidityxl 29cv3 qok7pt/f( qk?

  Which component of the cell membrane is represented by strucd j k4)p c3l9ijg- 4j2b3hlegiture X?

  Which of the following is not a fun c13b6k-ulju mction of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Whigjfj fc0y,j)ns, ygup*073 u kch letter indicates cholesterol?

  Which of these membrane proteins carrybmrnai67xxc l- fx hn.30*is/ out active transport?

Neuronal cells have spefv 9)-s7 a1hw vuyh6 y;nuym/ecial membrane properties that allow their axons to propagate action potential from one cell to anota nhm1fwvy 7yy-us h;vu6/ )e9her. 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 pol5g3xwe8* x dp0fgo7shar bear (Ursus maritimus), which is native to the Arctic. Which statement about the composition of its plasma membranes is cw *x xodghgp3e705 fs8orrect?

  Which allows cells to szhl ijy 28(b8.l ftne*tick together to form tissues?

  Some acetylcholine released by a motor neuron at the neuromuscular junction sti9nm* k8v 1w(lq(cwoio mulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes are required for this 1oc o mwi(9qv8nlw*k(to happen?

  
Which structure on the above diagram corresponds to the molecule below?

1.Outline the effects of placing a liver cell in a hypotonic dw(npl:n2nop x2 9 o4vsolution.
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 funckvw q5.zg41(sq xq w0gtion of membrane proteins?

  Which of the structures below can transport water molecules across the cell membjpnl c+p av+ ;:c7v0qmrane; pvvp jac0+q+7cl nm:?

  Which statement describes end2au*haz;n k1lwua7jyk+ 6/ l;asne* socytosis?

  In an investigation into the effect of soluteqrsn **ms nc0/ concentration 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 intervalm0/sn s*qc* nrs, 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 pot:kldi+0p h8 qnato tissue (Solanum tuberosum), cactus tissu0kn d8 ip:+hqle (Carnegiea gigantea) and sunflower seeds (Helianthus 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 gluc -m2 s*qeiv:ci)gl c;xamw/0 sose transporters in the small intestine, an example of indirect active tgie2:v0 wc; iq/xcml-s ma *s)ransport?

  Which type of transport is represented z8 gmt+3.c hx/r ts wz jj--hd(4,-cp6brqhqlby this diagram?

  Which row about the different mmrs +5-xraw e 2mvg7e;ethods of membrane transport is incorrect?

  Which evidence supported the Sin+ ;vrt zy4 (((qrwkxn lmtk;g+ b89tm4eof: vyger-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 d(fja;a ic:l 7model 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 percentage of a 4,dk 9ocvr*mcholesterol found in the cell membrane of epithelial skin cells of different an4 , avok*mrcd9imals.

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).