The important properties of animal cell p36+l0 qc da-kggu y(gmembranes are fluidity and permeability. Which molecule is responsible for ensuring g yk( g-c6puadqg+ l03the membrane’s fluidity?

  Which statement correctly describes the cell membrane structe urxz :xha3r0:)to* bqy5i 6y-; cypcure?

  Which structure represents a component respon tskd6t;tb4n rscwzw *c5-,;p sible for reducing membrane fluidityrt zscs;tw ;b5 d4,p-tkn *6wc?

  Which component of the cell membrane is represented by stro4q av6b akjkkbnp5*8c:g h4 +ucture X?

  Which of the following is not a function ocynk;2l9 b tvrmc 4)1of cholesterol in cell membranes?

  The diagram shows a plasma membrane. Which letter in(sben z:krgc): ls- g5dicates cholesterol?

  Which of these membran-r 8lv**s xxi:s+h knbe proteins carry out active transport?

Neuronal cells have special membrane properties that allow their a7xx z ydl))oau:rz66qxons to propagate action potential from one cell to another. The diagram below shows a portion of z uyxzq6) al7)do6: rxan 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), which iskyq 5ci/2q o2d native to the Arctic. Which statement about the composk 2qyq5dc 2o/iition of its plasma membranes is correct?

  Which allows cells to stick together to form go2cw*+5 xv om/l nl2ctissues?

  Some acetylcholine released by a motor kq1s;nw: trag 03lxo+neuron at the neuromuscular junction stim lo 1sq+t; aw:krnx3g0ulates muscle contraction, while the 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 of placing a liver cell in a hypotonic solution. 7r3csfz( wzjw i0-6 xe
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 membr0 rwvy(zyf70ik 5dw9 oane proteins?

  Which of the structures below can transp 1;di41knfwbe ort water molecules across the cell membran4n;1 iekfdb w1e?

  Which statement describ61aw.cjn3 8iqnmrs nw hd .p7f9jabd88*(ha wes endocytosis?

  In an investigation into the effect of sbp/z ip 8o4en//bue( qolute 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 takenp zb8ou 4q/bie(e// pn 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 tiss4++5c idv;itugw.axevzz3-u bpx4( u ue (Solanum tuberosum), cactus tissue (Carnegiea gigantea) and sunflower seeds (Helianthus annuus). Similar sized pieces of tissue were immersed in different solutions of sucrose 4dx3u g4v zbzwe-cit;5p+(a.uu+ vi x 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 transportei3k8z; oku5lnmn7t, a rs in the small intestine, an examplza,ntkm;85i ko un73 le of indirect active transport?

  Which type of transport is represented by this dia jsc b86sn y8 y*8hkxqp*x;o/mgram?

  Which row about the different mej ;x5msz,k* kythods of membrane transport is incorrect?

  Which evidence supported the Sizg +grs.wut-30 vsy7 g fv6,qinger-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 modeqy*) t37pvwd4gul+ r ,k tsj.wl 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 fqy fgj(vczl0xhi83 z i3q*lh* p(d05 percentage of cholesterol found in the cell membrane of epithelialfifhqcxzqd3i (hy0*p l g v*0j 5l8(z3 skin cells of 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).