The important properties of animal cell membraneqhlw h)hqb -cl7)u05fs are fluidity and permeability. Which molecule is responsible for ensuring the membrane’s flu hcwb q5qlul))-fh0h 7idity?

  Which statement correctly describes the cell membrane st +oxvw1f3z/p (qaw9h b xd).lrructure?

  Which structure represents a componena 9v,ojik1 3nexv-n sbfg+)5 m-6by vwt responsible for reducing membrane fluidit-bf6)i vnsgw,be1-kax95nyo+j 3v m vy?

  Which component of the cell membrane is represented by szwvj/c,pp ;mlkng:82 o( r ni zu0t95htructure X?

  Which of the following dfk7l3q0qi4 u is not a function of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicatz:8c-duw3cf h6 ,qrfq es cholesterol?

  Which of these membrane p)3 xx*uwll)h -5prlgvroteins carry out active transport?

Neuronal cells have special membrane prdy, 7p1f giqgykqw)5 mks,-vt+m 2sd 6operties that allow their axons to propagate action potential from onqks)7gs -+, kpd26mm, v yfdqitwg15y e 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 polq .2v)bq, fbga,+litbar bear (Ursus maritimus), which is native to the Arctic. Which statement about the composition of its plasma membranes is corrq vlba,g )2.+qtfibb,ect?

  Which allows cells to stick toghxxw4+9j) 0sljqa d g3ether to form tissues?

  Some acetylcholine released by a motor neuflg , slw/za9 u*r8ol 9(jvt0uron at the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removedrulgj9a9s0 *oz wflt( vu/8 ,l 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 liver cell in a hypotonic solutd0oimv+ x918t4vkrfz1+ nyv cion.
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 functioyrx t7o(puh4 ;n of membrane proteins?

  Which of the structures below can transporjc*u gjn q/9k2t water molecules across the cell membr9*n 2jjgcq/k uane?

  Which statement descrds2o) q*iur ;;9ae1gskkh8bp ibes endocytosis?

  In an investigation into the effect of solute concentrati sm3;,yv rxge2nv 8z*y15sju8;imqyq on 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 fromm2svys318ryq z;u8* e g5; qj mvi,xyn 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 hdu()g6a ;vx lan experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue 6gdx; ( alhv)uwere 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 glucmbp53 t-9*t9 tnje cq 5ainfvmvv*(l(ose transporters in the small intestine, an exam ljte*tnv- (v( 5a99*fp3nctbq ivm5mple of indirect active transport?

  Which type of transport is re p( /iwae0y6rspresented by this diagram?

  Which row about the differene8a);r 3 oupw0xt mhk;.xnu( wt methods of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson 6) l3h3 .kqizyfh1pw nytc ,v9model 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 ofbc; jvqp0+q,j2 q 8bevv8p8sz 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 sb/, f rze f0t.b(lshe7-ws*m avy9bqc5d: u1 wtudy on the percentage of cholesterol found in the cell membrane of epithelial skin cell/ qat5d sb,rv0ce-b w1febm:lz(wy su7 9fh.*s 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).