The important properties of animal cell membranes are fluid3 ; 6.9jbwjn nakrncz+ity and permeability. Which molecule is responsible for ensuring the membrane’s nn9 b;wjcanj.36+ krzfluidity?

  Which statement corrd 4 tteq.h*)r:hvl;e cectly describes the cell membrane structure?

  Which structure represents a coalg+8seij j37 9s-nelmponent responsible for reducing membrane fluidity? g9j38aslsl j7ie - +en

  Which component of the cell memcwsnh)y252c dnz.c+ag h), y mbrane is represented by structure X?

  Which of the following is not a function of cholesterol in cell memb)zz w9( +jt:bbl nrg4,8rnfigranes?

  The diagram shows a plasma membrane. Whije:mcxrw +d :/ch letter indicates cholesterol?

  Which of these membrane proteing-pu995ghq r vs carry out active transport?

Neuronal cells have special membrane properties that allow oif80 fvek.9,:mri m/.b kplw their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal plasma meb ei mrm8,/wfo:i kplf.k9. 0vmbrane.

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 p ;5g3qb1juukt n1v;3k/ trxa (Ursus maritimus), which is native to the Arctic. Which statement about the composition of i3t u 1 rgja;5nkk3x /t1ubqv;pts plasma membranes is correct?

  Which allows cells t7h1/qh .mbx qeo stick together to form tissues?

  Some acetylcholine released by a mot iw3zf4dqdikei67bf yd4b(cti5 9 4)tor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes are required for this edii ibt4yc4d6bkfw4q7 (d ft3 95) izto happen?

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

1.Outline the effects of placing a liv d66msesf.b1 qer 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 followin 2u7hyd1cvvb3g is not a function of membrane proteins?

  Which of the structures below can transport water moleculesv37 e7;46jfyb5ui/ sthzqx xn ,sj: yx across the cell membranez xh76bsx:fy; ie/q3jntsyvu4,7x j 5?

  Which statement descri t( wlp6jeb)i;bes endocytosis?

  In an investigation into the effect of solute cony b)ks *v)idj42l0f y4a.ktzz centration 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 ti bskzt j0y2fa i4y4.vkdz* )l)les 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 o3ss9 4d9p6ev al;0bmyb-lhpzf an experiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflow;lybzpdh b4s93mel9v a0-s 6 per 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 glucose transporters in tq6sz i*8 fpgy17iud3a6bk /arhe small intestine, an example ygadfb a3uir 7is8*6p / zq1k6of indirect active transport?

  Which type of transport is repre+t ewabxd6u *:sented by this diagram?

  Which row about the different methods of membrane transport is incorre3m ck* vf;5gwkved *c9ct?

  Which evidence supported the Singerf uhsp-f8ze0(-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 model of a cell’s plasma muw.: 8ldx;2hcplzes .embrane.

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 59wyvgvwf4 b+- z7qp 7nj- renresults from a study on the percentage of cholesterol found in the cell membrane of epithelial skin cells of different 7w-4gyv nwj +z- rq75pevnbf9animals.

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).