The important properties of animal cell membranes are fluidity andr : d o0,uqhh kc:/mc6-d*jkqp permeability. Which molecule is responsible for ensuring *-rqq0hd/k:hdp u,c mc6k:o jthe membrane’s fluidity?

  Which statement correctly describes thc 0vn*djdy 77ki. fex+e cell membrane structure?

  Which structure reprenvrb5e,7mau v x )0-2oiv7l btsents a component responsible for reducing membrane fluidityai)5-,2u ln vve0r7b mxbvo7 t?

  Which component of the cell mq /m vh4s; zw7)a;ohayembrane is represented by structure X?

  Which of the following is not a functionydlcar j) 3)j6 of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which letter indicatehd4/lx(c 2xrz9mn77qu3pv ajb d,c)fs cholesterol?

  Which of these membrane proteins carry out active transpp)tj h7bqgf km;:03, odypqx8 ort?

Neuronal cells have special membrane prok5 e ;0u7aayjprn4 qf8q pz7,tperties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal plasma m;rq nke4upa0p77 aq ,t8zjfy5 embrane.

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 bearf0x,fp . yu0zi (Ursus maritimus), which is native to the Arctic. Which statement about the composition of its plasma membranes ip .u0iffx,0 yzs correct?

  Which allows cells to s)o (9jgvm txigrypy5 ;6tp6m2tick together to form tissues?

  Some acetylcholine released by a motor neuron at the neuromuscu1 r3 )qpjfquz5lar junction stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes a 5r31f) zjupqqre required for this to happen?

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

1.Outline the effectsll7 myryk6v 71 of 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 membran7 w.aa0w.tp7pog lp8 ee proteins?

  Which of the structures below can transport water moleculevdgwa +l9 f81vfq. s(s1nnke :s across the cell membran k+nwql1vsv.df1e:gf 8(9nase?

  Which statement desc-22b n qdzuqa.ribes endocytosis?

  In an investigation into the effect of solute concentration on diffus mdzrzg1*m9)x8c( xpuion rate, starch solutions, of varying concentrations, were placed inside starch permeable membrane balloonzrz g m*xc(u8xd9p)1ms. 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 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 potato tissue th2q5- wl1aft 4r p58bt tg1bt(Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tiqb 5rahwpt 2 -tlt41 5t1btgf8ssue 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 i4.(t/ oh y b+.qknfcr+lesv i0n the small intestine, an example of lec qos0k(fr+ +n/t .h.vi yb4indirect active transport?

  Which type of transport is represented by tb. nc)(2 wl/h5l bytqvrmk05fhis diagram?

  Which row about the different metd a )g4wq b8dr1zxd/5lhods of membrane transport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma mr2e d,xfmlz 6-embrane?
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 mrfh1d(7i8y zcmnc7qh o-qv lnr0 . m,7cahy3.osaic 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 ly1 ab5)v j4zjpercentage of cholesterol found in the cell membrane of epithelial skin cells of jj45v )lyzb1a 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).