The important propertie5xy4,p-hjjpn 2pm2m:: r b oh)weq w5ds of animal cell membranes are fluidity and permeability. Which molecule is responsible for ensp 5 :e)2mrh,hb:xjn24ww o-pdmp q5jyuring the membrane’s fluidity?

  Which statement correctl 6*l x2sjpz6say describes the cell membrane structure?

  Which structure represents a component responsib+4i32r1wn ga bcbm85 eyqy65p+yh; oun/rh yzle for reducing membrane fluidityyrbw 43oy; abcu/r m2g 1ne yyi+hq+ nz8ph556?

  Which component of the cell membrane is represented b w*es6zzv5 s 5*hrfrasjfi8 h c21jp,)y structure X?

  Which of the following is not a function of cholesterol in cell; k3tepxysdrw35s * )g membranes?

  The diagram shows a plasma membrane. Which leauy4/gdpmp pe,7ma ; /tter indicates cholesterol?

  Which of these membrane proteins carry out activeuxzqd5 u r7y 7-a9f:cb transport?

Neuronal cells have special membrane iapw;0rxpj l ,hxk79 9properties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an j;xap wrp9x i0kh79,l 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 polarwh. /un )f.82 ejrcbyav:yh d7 bear (Ursus maritimus), which is native to the Arctic. Which statement about the composition of its plasma membranes is correc8fnevd..hu/y2a by)7 j h wr:ct?

  Which allows cells to stic dg n5+whm7s3jk together to form tissues?

  Some acetylcholine released by a motor neuron at the neuromuscular junction e+oci c*lr .2hstimulates muscle contraction, while the remainder is rac 2horc. l*ei+pidly 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 placing a u t0( m:8 v/x7etuqhyp av63bwliver 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 58umli e)dd nxu)z x:b/z -xm4membrane proteins?

  Which of the structures below can transport water mo3*)f+9hszlg ji jb;q olecules across the cell membr9gs;b*il)j3z+jh qo fane?

  Which statement describes endocyt;z/ z d 03.hmxbvueh mgd4v*y*)emd- gosis?

  In an investigation into the effect ofbgq5n15+kuc 1fy rc +x 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 positive test to show was recorded for each tria xbury1k5+1cnq+fc 5gl.


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 experimruf* *hgiljodt5yeh;q7mq8cey 0( /7 ent on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue were 50/7dhmqq ;cjy7*e8*tl ih( f ygeuo rimmersed 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 iex e4/z90 m-u ink;xdtransporters in the small intestine, an example of indirect active transpor9xe;m d40 k-inxiz/ uet?

  Which type of transport is represented by th/8jfqd2 ycttn guz8):4ozv1 3 j 4kjiois diagram?

  Which row about the different methods of membrane transport is incorrddial)/ s: g.v*i xac4( yrrq3ect?

  Which evidence supported the Singer-Nicolson zp8xdpu 0 3.k mrsw.w.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 flum a2), 8*qf;tpqilqml4a.q etid mosaic model 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 percent1cdrk5ye )/rl pey v-9e/wa:w 05jd arage of cholesterol found in the cell membrane of epithelial skin cells of differjayrre1 w/evwd9pe5) ak 5 0- rdyc:/lent 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).