The important properties of animal cell membranr dcwvt*f1jb3be;t8+( i 8 wbfes are fluidity and permeability. Which molecule is responsible for fw; 3+d* v b8wrt(ecj8tbb1fi ensuring the membrane’s fluidity?

  Which statement correctly descxk/noeg siy-y0x /dy( s.bo7o0 dt 6v*ribes the cell membrane structure?

  Which structure represents a component responsible for reducing membrane fluiditcg.m or 3erby*he*:y 8y?h yry8eo:m3r *e .b*gc

  Which component of the cell membrane is represented by structw.yk2v1/t / o)mi;ooph zpz:yure X?

  Which of the following is not a function of cholesterolf2u(yni; a7u w in cell membranes?

  The diagram shows a plasmv n-i54ot:qbmxj,( e da membrane. Which letter indicates cholesterol?

  Which of these membrane proteins carry out active te..kphrj2k4hmoeh4 vk 1 5 uh*j;rm z3ransport?

Neuronal cells have special mem/wvrdq m 7rngie ,qms91r k;-v(kp2*wbrane properties that allow their axons to propagate action potential from one cell to another. The diagram below shows a portion of an axonal plasma /gi2, -wmrprq( s wqd9 v;en1m7kvkr* 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 (Urs-,zy,xq0 aogsus maritimus), which is native to the Arctic. Which statement about the composition of ogs, , 0qz-xyaits plasma membranes is correct?

  Which allows cells to stick togethe(72vlq yo7xcx44/ zsyykw 8 ver to form tissues?

  Some acetylcholine released by a motor neuron at the neuheul n hz e,pj+jdq/ah f5pqm5144n,7 romuscular junction stimulates muscle contraction, while the remainder is rapidly renmd5j+fqln,u 14z/p ae,5 hq47eh j hpmoved 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 solution. 3pj; 5eojfkyzx 1l.y7
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 nady p ri*h(0-cot a function of membrane proteins?

  Which of the structures below can transportse3rn5; 90 w d,f1xetnjo v)mt water molecules across the cell membrdn;efrj te w )5v0x3m,nto9s 1ane?

  Which statement describem,fx7u- zer 50lixr b4 0/znnxs endocytosis?

  In an investigation into e(f9.jq lp;d ythe effect of 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 a.fdqlj9( p;ey nd 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 tissue72vb1d/ je6g +pnc dxy (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue were immersed in different solutions of sucrose for 30 h jgbc+de6d/v7 1 ypn2xours.



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 sodci g) q* nhhvrnfcq9z858r: o)ium-dependent glucose transporters in the small intestine, an example of indirect acqnnv h)*o8i)gf9 8rz 5r:qcc htive transport?

  Which type of transport is represented by this6c05tw2ibt y s5 y/x ,qfnz(ja)+dhfw g ox*v+ diagram?

  Which row about the different methods of membrane transportqcc-biz4*;ej is incorrect?

  Which evidence supported the Singer-Nicolson model of the plasma membd/9rfyic9smd an6;od0 mu81brane?
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 mode tfx: f6v*szzes4 dpf f66ho ag.3k.j:l 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 cholesterol found3x/ 3wit 95t tgdgaom6 in the cell membrane of epithelial skin cells of different an36 t3 tg omawg9it/d5ximals.

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).