The important properties of animal cell me w3i0m svu))qkgq .g/qbq6eo6mbranes are fluidity and permeability. Which molecule is responsible for ensuring the membrane’s vsgq0uo)q6 b) qw3/qmgie6k .fluidity?

  Which statement correctly describes the cell membran6 /;b;epzpug.wrx -tb -t+qu ne structure?

  Which structure represents a component responsible for reducing mj -)jfp9a -- jrxy;x rubll--hembrane fluidity?yx-f ;-jr- r)-ljh -pj lxabu9

  Which component of the cell membrane is representlb2w,ds6 ;yz; mv/h hwvb11 gped by structure X?

  Which of the following is not a function of cholw+npdh xj c5++9ezh, festerol in cell membranes?

  The diagram shows a plasma membranx66nm:wix 0ebp:91n 5sc gjk/ x zh6gfe. Which letter indicates cholesterol?

  Which of these membrane proteins carry out pazmqcuh0 22y-g6 + l0rlue o5active transport?

Neuronal cells have special membrane properties that al7+h it-ukgy0w ) )izntlow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal plasma m0it knhwytg-7 ) z)+iuembrane.

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 nativvb+mj*,b qc,g e to the Arctic. Which statement about the comp,mbbv+ qg,c*josition of its plasma membranes is correct?

  Which allows cells to stick together t1zyvz j csidv.cbwp.rx3 m zq8://*a6o form tissues?

  Some acetylcholine r271njc(m18rd5yk*m.rzp/gc wivl du eleased by a motor neuron at the neuromuscular junction stimulates muscle contraction, while the .umv iccldn5wr/2kgm8d*71 (zyj1 prremainder 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 op1+ oa; s svi0jcr34jxf placing 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 y3;z x obu8lejjv;hijl.z3-f x s:(2b membrane proteins?

  Which of the structures below can transport water molecules across the cell meakp4e.+ +q upqmbra++ a.uq4kp pqene?

  Which statement describes ;p5xo w9fl6m wendocytosis?

  In an investigation into the effect ofzi*sb:p x+auq 57 q5qr1xjz5t solute 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 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 pos + 5jzqt7z5r 1qpi5xq* :bxuasitive 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 rmsrog6f+ +31as dc9a wesults of an experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tiss+ csaawd9 g6r1fos+3m ue 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 small in: ,w ukgn po;8ub6v9jatestine, an exampvj, :p;ug nwo68b9uk ale of indirect active transport?

  Which type of transport is reh+f2 az u4u4e ,bh+bhopresented by this diagram?

  Which row about the different methods of membrane transport is incor8nrkk8o(yi1co 6kk3 +f3nzlv rect?

  Which evidence supported the Singer-Nicolson model of the plasma membranev 7: m:0 do6bfiws9jjea rlr;9?
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 ed o.2ty3 fivxvy)8f. 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 vfxpt/;8m- xestudy on the percentage of cholesterol found in the cell membrane of epithelial skin cells of different anit m-;f8x ep/xvmals.

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).