Which of the following ma)xe yv*ogyc /1cromolecules describe a typical enzyme?

  What type of reaction k.yrbzco :04zis photosynthesis?

  What is the substrate for the eo 5 fb6g7:lo k*zmf)qanzyme lactase?

  Which of the following stages of cellular respiration takes placebwzup1u8z3;+f)ez dxgp .ef+ in the cytoplasmpep.d e81u xfzbf3+uz;+ g)wz ?

  Which of the following would not be useful in determiningv5mcv-8r ykgb,deb 9 1 the rate of an enzyme-catalyzedb85 - byv k1mv,grd9ce reaction?

  Which of the following processes may be describesi 6e6fe1 jx0xy+0 ovhahi*tb8: gsm :d as catabolism?

  Which of the following statements is nqqi.wlz:+t d 3z.p/ pbest depicted by the figure below?

  Which statement about enzyvt9bo ocqk kw9b)t1s ;+ fx,+dmes is not true?

  Which of the following graphs best illustrates the relatinkncw ,m9e0 c1onship between temperature and the mn90k 1cenw,cactivity of enzymes such as lipase?

1.Sketch a graph to show how incregt2 er;3dj mxxslu*2w g q9ztd6 x7w)9asing concentrations of substrate affect enzyme acti9djx wgz)g xe96w2*x7tdsr3 tuq ;ml2 vity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a serie uqau7n1alf5m9-3rrunf/)z;a mdrg8s of enzyme catalysed reactions. A diagram outlining the Calvin cycle is sho15l)m9/8nufardaz -f gu7mn3rruaq; wn below.

The image below shows the catalytic site of an ec i95jooojq0ne+h* ri.fkp 2, nzyme. The substrate is shown in black and ishecjo5 r.i02 *9ko+n pojqfi, bound to the active site.





1.State how the activation energy is changed by adding an enzyme to a reaction.
2.Distinguish between anabolic and catabolic pathways.

  Which are correct descriptions of the enzyme catalysed metote5c/r2w (o zabolic pathways shown below? Letters represent various products of individuao t/ erwoz(5c2l reactions.

  Which of the following describb4+ 0y.w tjbnq:uqco7es the role of inhibitors in enzyme-catalysed reacc+:0 n7wyqqb4o j b.tutions?

  Which of the following correctly des-bbpll4/ sgx f6i)nb 1cribes photosynthesis or respiration?

Many enzymatic reactions happen as pathways inp5f(nku9 vt u:volving multiple steps and multiple enzymes9k5p: nfuutv (.

1.Describe how enzymes catalyze reactions.
2.Outline the advantages of enzyme-substrate specificity.

  Which of the following best describes the inhteex+g mlsod42 us89j4 ,rrt7ibitor in the image below?

  Which of the following statements are true regardi)hu cfro.gi5+sctmc :11aq scyr1l19 ng regulation by end-product inhibition c.1 r+sg ccf)hy5sm11aqo1 c9turil:?
I. The end product binds to the allosteric site of the enzyme.
II. The binding of the end product is reversible.
III.End product inhibition is an example of negative feedback regulation.

  The following image shows tuogho n)j5d + .4zc.(6gl+ fje9duizlhe structure of the lysozyme enzyme. The darkened structure in black is the substrate anjz.6 oeu(n+ dzfl5 .duhg gci4 9o)+jld is bound at the active site.

Which of the following characterizes the active site of an enzyme?

The equipment below can be used to study the effect ofn y0d7evqbgk 2+oa t;9 temperature on the activity of the7g90;o2et nbdav ky+q enzyme amylase.



1.Outline how this equipment could be used to set up a study into the effect of temperature on amylase activity, up to the point of getting the results.
2.Outline how the rate of reaction of the breakdown of starch by amylase could be measured using the equipment given.
3.Describe a suitable control experiment for this study.
4.Suggest one way to increase the reliability of the data that can be gathered from this experiment.
5.Using the axis below draw a graph of the expected results from the study in part (a).

  Which of the following statements describes how enzymes interact with substras tzs6 - bl0svad(p-cy*l13lvtes to cav -*lls6z1dtc03a syvslb (-ptalyze reactions?
I. Enzymes and substrates in solutions collide with one another, and the substrate is bound at the active site.
II. There is more movement of the substrate in a reaction because the substrate is usually smaller than the enzyme in size.
III.When the substrate binds to the active site, the shape of the enzyme changes slightly so it can accommodate the substrate.

Outline two ways enzyme catalyss8,t7 ,ev fquyed reactions can be measured.

  How does denaturation change the pr- .6mm kbngpe**r,t xlie6 *vsoperties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the9tq;e:o:ktmq9. omy ,c3 b liq following statements are truel;9 k9mmqoc q3betq iy,o.:t:?
I.The substrate is temporarily provided with energy before being converted to a product.
II. Enzymes reduce the activation energy needed for the reaction.
III.The active site binds to the substrate making it easier for bonds to be broken or formed.

  What is a characteristic that separates mammals or endotherms from ectotherms dua 5z1e2qi(bgx(n i n+*p8 dqij,-.xki i1wathat have fluctuating i5ax(nxie n+-d 18 wzkq*(b.i, qjpu1ag i2idbody temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucghrdqxf.pr0 .57 6 inv1)rsyka )6 mda3nf i:rine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the lrf.rn3rngaps fiydar1ivxd.m)6) 0 7:5q6kh ast enzyme in the pathway.
In the following diagram, the enzymes have been labelled as E1, E2, E3, E4 and E5.


Which of the following shows how this pathway is regulated?

  The graph shows the effect of increasing pH cms 30jtn i y421xdvg2tj j1a/on the rate of an enzymatic reaction. Whjjv0d3 xcm2 g1ti/sja41n t2yat is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of ch7q9p5gqsod m2anging substrate concentration on an enzymatic reaction. 52 go7pmqqsd9What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts tgq.r+qf.kc p5 hreonine to isoleucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobmb0x(j57a yqx ilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-ym 7a( xqbj0x5axis) with varying pH (x-axis).



Which of the following statements is true?
I. Both soluble and immobilized enzymes are inactive at higher pH values of 8.
II. The immobilized Enz A is more resistant to pH changes showing more activity than the soluble enzyme at most tested pH values.
III. Immobilizing Enz A did not decrease its catalytic activity.

  Purified enzymes are easily denatured. Whic 1u nab ,n(0nlj:ms)fqtn*n:qh of the following is the best way to keep enzq,:m 1f(na b:nsj* n ntn0)uqlymes active for a longer period of time?

  Which of the following describes some types of extracellular bf 2d emnyqg a6*w30wgnan-3)enzymes?

  The enzyme pepsin hydrolyses proteins to relev:4 vebr( rfhsd/wd 4:ase peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a cons ev : 4(/vfh4rwrsb:ddtant temperature of $30{\circ}C.

1.Describe the trends shown by the graph.
2. 1.Outline why it is important that temperature is kept constant in this experiment.
2.State one factor other than temperature that would need to be controlled in this experiment.
3.Suggest a method that can be used to maintain a constant temperature in this experiment.
3.Calculate the rate of reaction during the first 4 minutes when the enzyme pepsin is exposed to 5 mM of protein. Make sure you show your working. ----待选择----+-   
4.Explain the observed results.

  The graph below shows the rate of reaction of an ewd99m,. yk ctns gff4dw..gh)nzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monitored for each of the reactions. )wf.,nf .gdt .h9d4g9wmcy s kThe curve marked A coincides with the activity of the enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a tl ( qe2kakfh.(urnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The homogenate w2hkk.( e(aflq as filtered and the liquid extract was stored in a test tube at room temperature.


The turnip extract and water were added to the conical flask first. Then 3% hydrogen peroxide solution was added to the conical flask, as shown in the image above. The oxygen produced is collected over 1 minute and measured in an inverted measuring cylinder, as shown.
The student wanted to conduct an experiment to see the effect of increasing enzyme concentration on the reaction. She made up the different concentrations as shown in the table below and added 1 ml of 3% hydrogen peroxide to each.

1.Suggest why the process of grinding the turnip root and extracting the filtrate was carried out.
2.State the dependent variable.
3.Explain why the volume of water was varied, as shown.
The following graph was obtained when the student varied the substrate (hydrogen peroxide) concentration, keeping the enzyme concentration constant.



4.From the graph shown above, calculate the percentage increase in volume of oxygen gas produced when using 1% hydrogen peroxide compared to 0.5% hydrogen peroxide.  %
5.Outline the reasons for the shape of the curve obtained.
The student repeated the same experiment but added an inhibitor along with the enzyme to the reaction mix. She got the following results.


6.Deduce, with an explanation, whether a competitive or non-competitive inhibitor was used in the investigation.
7.Other than the factors already mentioned, state one other factor that can lower the rate of an enzyme controlled reaction.

  The mevalonate pathway is shown bmw5;s 3la ;foy bx tm)+yap:j3elow. Inhibitors to the enzyme HMG- CoA reductase can lower the production of chol3:ax ljw 5;m;3om bypts+)fayesterol.


Statins lower cholesterol, reduce the risk of heart attacks, and prevent strokes. They are known to inhibit HMG-CoA reductase, which is the rate-limiting enzyme of cholesterol biosynthesis in the mevalonate pathway (image above).
Which of the following describes the mechanism of action of statins in lowering cholesterol?

  Which of the following are involved in denaturati ) k+trk.ot.kcon?
I.A change to the three dimensional structure of the protein
II. A change in the amino acid sequence of the protein
III. Changes in the properties of the protein

  Students were investigating metabolic re y-z(bk0lq/ oko6cl 6gactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reactiolk k6g0-boc/l6 qy z(on.
A sample of fat was added to a beaker, which contained 150ml of a 1% sodium chloride solution.


The beaker and its contents were then added to a water bath, which was set at 15
o
C. The beaker was given 5 minutes to equalise with the temperature of the water bath. After 5 minutes, 5 ml of a 2 % lipase solution, at the same temperature as the water bath, was added to the beaker.


5 ml of 2 % sodium hydroxide (NaOH), pH 8.4, was added to a test tube and phenolphthalein, a colourless solution which turns pink in basic environments, was then added. The intensity of the pink colour is proportionate to the strength of the basic solution.
At exactly 20 minutes, a 5ml sample was taken from the beaker incubated in the water bath and added to the test tube.

The contents of the test tube were then immediately transferred into a cuvette and placed in a spectrophotometer set at 420 nm. The percentage transmission of light able to pass through the sample was measured and recorded.

The procedure was then repeated using water baths set at a range of different temperatures. The measurements were recorded in a table and presented in a graph.



1. 1.State the independent variable in this experiment.
2.Identify two factors, not already mentioned, that would need to be controlled in this experiment
2. 1.Explain how the spectrophotometer is able to measure the breakdown of fat.
2.Explain the effect of increasing the temperature from 15
o
C to 35
o
C on the rate of the catabolic reaction.
3.Predict the percentage transmission for a sample incubated at 20
o
C.  %
4.Evaluate the claim that based on the data, the optimum temperature for lipase activity is 35
o
C.

  In an experiment, the effect of increasing5mi pfq -)mcpw;t )pi.pec6z7 temperature on the efficiency of lactase activity is tested. Which is an appropriate dependqp7 cipm.pp )6);z5mite-fcwent variable for this experiment?

  A study has been conducted on the activity e h87p)o roew.of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potent)po . e7or8hweially be used as a commercial lactase to produce lactose-free milk.



1.Deduce which temperature used in this experiment was the optimum one for the enzyme Bg10. Give a reason for your answer.
2.Explain the change in enzyme activity at temperatures above $40^{\circ}C$.
3.Evaluate whether the data supports the claim that the optimum pH for the lactase enzyme Bg10 is 7.

4.Calculate the percentage difference in relative activity of the enzyme Bg10 when treated with 500 mM of glucose compared to 50 mM of glucose. Make sure you show your working.  %

Further studies have been conducted on other lactase enzymes to test their thermal stability at an optimum temperature of 60°C, when they are immobilised on graphene nanosheets, in comparison to lactase enzymes floating freely in milk.

5.Compare the trend shown by the immobilised enzyme to that of the soluble enzyme.
6.Calculate the range of data for the soluble enzyme over 10 minutes.  log %

The storage stability at room temperature of the immobilised enzymes has also been compared to lactase enzymes floating freely in milk.


7.Compare and contrast the storage stability of the immobilised and free soluble enzyme.

The reusability of the immobilised enzyme was tested, by analysing the activity of the immobilised enzyme over 10 uses.


8.State one advantage of being able to reuse immobilised enzymes.
9.Using the data provided, and your own knowledge, suggest why immobilised enzymes should be used to make lactose free milk.

1.There is a continuouced76a jr*xqe9p3p l;y g7*/og5m4e8ej pcdls need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are be* md8r5 4jelgeoclqg 6pjee; p797xac* 3pyd/ing discovered with new technologies.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.

1.Explain how increasing the concentration of an enzyme affects the rateh -6 4337gz9;zm j nrv3ktng6plbbqbz of reaction. r37g3g z- 4lbpb vnzj; 9k63b6hzmtqn
2.Lactase converts lactose to glucose and galactose. Outline how lactase is used in the food industry.
3.Discuss the industrial use of immobilized enzymes using a named example.

  Biomolecules can be broken down or syntea8mi, rro1sm.eh 3,uhesized through metabolic reactions. Which type(s) of metabolic reacth1amur3,e 8. ,imroe sions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed re 22biy6i ljgxo4xip ljfi9 .45actions can be measurxbjgil iii26.ly9f24xo 5jp 4ed.
2.Draw a graph to show the effect of temperature on the reaction rate of an enzyme.


3.State how the optimum temperature can be determined using the graph drawn in part b.

1.Compare and contrast intracellular and extracellular chemica9mslt+qcl*nkotn -v e;k4 4 4ul reactions, given on49cs;uv+l mo4*n e 4kqlkttn -e example of each type of reaction.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.