The important properf)k3/tu o xm(fties of animal cell membranes are fluidity and permeability. Which molecule is responsible for ensuring the membrane ou(3kf x)tfm/’s fluidity?

  Which statement correctly describes the celvig 4+:n xqdsqi5xv37l membrane structure?

  Which structure represents a component responsible for reducing me 86lue;n* +ozx a:jotwmbrane fluidity+uwa :jnxzl o;o e*t86?

  Which component of the cell membrane is rep*ayps;ah:z81bo2 jqwresented by structure X?

  Which of the following is not a fwj* qe0v2 dzham33 2qn3xfeh9unction of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which letter indict t(z wqd6v q:pzf-d.9o ,g:uhates cholesterol?

  Which of these membrane protwfzik0ud *5j * 5z(giteins carry out active transport?

Neuronal cells have special membrane properties that allow their axons to propag f2y31e6lirzsn: 0d ceate a :16ere 03 isnlzdyfc2ction potential from one 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 polar bear (Ursus maritimus), wiif2vvias (-wxy;60 l hich is native to the Arctic. Which statemev2-y6 (iaxi lw0;vif snt about the composition of its plasma membranes is correct?

  Which allows cells ti 5jp : ;qr2-(nwrfizzo stick together to form tissues?

  Some acetylcholine released by a motor neuron at tq17 fui*mfd aync1* u(he neuromuscular junction stimulates muscle contraction, while tdf7imf(u1*aucy n q1* he remainder 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 ) r 9y*tncqjqad:3i e1of 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 fus- )li *ecwl8kj)4ivdnction of membrane proteins?

  Which of the structures below can transpo d4uf9l48 qcxort water molecules across the cell membrane d4co8qf49u lx?

  Which statement describesi ziq*x53awp / endocytosis?

  In an investigation into the effect of solute wb 70p( baya:iir k8v),iow3f4ixk . gconcentration on diffusion rate, starch solutions, of varying concentrations, were placed inside8kbgf3 ,o iw .:k4piwraxbv0i)yi7 (a 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 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 ejh0xrc;/ d1.uk6( ko1duaqcl xperiment on osmosis in potato tissue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue were immersedocq/h60d k 1.jcra;uu(k l1x d 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 i,()nfdo6 ,4bljkz eojntestine, an example of indirect activejknd6eoj 4zo,) fbl (, transport?

  Which type of transport is represented by this diagram?vvfzo2vid:nr1 s7 *7f

  Which row about the different methods of membrane ,:ctec - ddd1ptransport is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma membrane t)y(c9qqxe 1ukxf,n6 ?
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 fluic g795urkxlkh .-8n ghd 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 percentage of cholestero-/9uk- *j adcmwouy5 0m /asfbl found in the cell membrane of epithelial skin cells of different animauks0b* m wda/ /a9 -yfjcm-5ouls.

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).