Which of the following macromolecules describe a typical en2z+ 1ulm0yny+rgdi u7zyme?

  What type of reaction igpm6 2y)er8 a 4yhiv/c*juuu jdh:w6; s photosynthesis?

  What is the substrate for tnfbl/u; nb19akzpl) 6he enzyme lactase?

  Which of the following stages of cellular respiration takes plzv, lsen;udmrg1 ,uhs 1e+q05ace in the cytopla 0e,,l dssg uum;51nvh1r+qzesm?

  Which of the following would not be useful in determining the razac ;7ag jlpak*j,+i8oahb ,,k m( ;jqte of an enzyme-catalyzed reactioalz ;jka*hi7ojg+q8; a b,p, k(ac,jmn?

  Which of the following processes may be described as catabo3ep,rxz y+o8g lism?

  Which of the following statements is best depxt.dqw0 doiexf (814gicted by the figure below?

  Which statement about e*)gkxqpscs); lxfdo l5po: ;2nzymes is not true?

  Which of the following graphs best illustrates tmfgh1 bvo-r.(he relationship between temperature and the activity of enzymesb.-hvgo(f m1 r such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affkb8 i474 6ag;+aago 5urlpzcw ,if;ngect enzyme,i+f;7 a5 z4 kgg a84wb;c6unglroiap activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of eqj.9 f/fts4h vay i4x2nzyme catalysed reactions. A diagram outlining 4six fjv2yht/q4f9a. the Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is shofwxl d*k0 64xnq;pw3 dwn in black and is bo4qk6f* dp xw3d0w; nlxund 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+;9z8l yk 7cu:av3ooc5naes l metabolic pathways shown below? Letters represent vari87vzoca : 5lya+cu kn o93;lseous products of individual reactions.

  Which of the following describes the role of inhibitors in e4a0x+m0atbjzq-bo 2onzyme-catalysed reacti+o -0 2bzmjaxqb0 oa4tons?

  Which of the following correctly describ(g ol 5 /o,o:-ck1sucfyx 6eqx 1yf)szes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and my1ux//z n/i 6vy0qcgmultiple ev1y0g q/ iy /m/zucn6xnzymes.

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

  Which of the following best describes the inhibitor in theefx/ h8;,a6z 6t3*lyex akqgk image below?

  Which of the following statements are true regarding regulatc wz3 bvs+ca)b9r)5z oion by end-product inhibitiaz+5bs)vc o) 3b9wr czon?
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 the structure of the lysozyme enzyme. The darkened stv/: ywu5ispq .ructure in black is the substrate and is bound atuw5 isp/.vyq: the active site.

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

The equipment below can be used to study the effect of r0 zg-: dvs .5hiite9:isnd) pkfn3;btemperature on the activityiz- n ip0sn. :)sbd; :ikfv thrd5ge93 of the 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 sta0( bn,ghvl/bcm2;s6 bet s; xttements describes how enzymes interact with substrates to catalyze reactio ,b 0h ;vtbt;eml62gb c(/sxsnns?
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 catalysed reactions can be measucg8k m: i9.hvkred.

  How does denaturation change the propege/ki 8)7lb serties of an enzyme?

  Enzymes play a role in catalysing reactio+; naxli1 zfy uq,1ql,tk9i) qns. Which of the following statements are t ft; )1k1n+ qlizl,,q9aqyixurue?
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 ectopt-x6lnrful n7,n .(6h3jgno 61uh z3 dxsbc3therms that have fluctu6b,lhj 3gxfsxnnd.6r3l h3( unn1cotp 6u- z7ating body temperatures?

  A metabolic pathway that,pqkf11yyc pstz42 : t converts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intkcf:q21ytp,y zs14 t permediate products sequentially by different enzymes before it is converted to isoleucine by the last 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 effectevz-bj v-+elzu2; k+r of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled -l;bke ezrvzj2+ +u-vsection X in the graph?

  An experiment tests the effech-/mm -42cfgmt *6d8 d3 kxjfg 1yccket of changing substrate concentration on an enzymatic reaction. What could be thkhf jd1*ycdm4/g-ecm cm-3 k gf6t8x2e independent and dependent variables in this experiment?

  The diagram shows the pathway lu g;l.jw 8h-:vvv(fc that converts threonine to isoleucine.



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

  Enzyme A (Enz A) was immobilized on a matrix and its activity wawv do *x qrt7a r5)qa52ugj2i/s compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x- 2wux a5o*r)tj5 i2a/ v7drqqgaxis).



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 denqpbb*y 9t*vr*atured. Which of the following is the best way to keep enzymes activeb9b*vp *tyqr * for a longer period of time?

  Which of the following describes some types of extraceli o4txcnhj fi;y-;r,tyh6 81olular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A studa79of6p 6jk9 gd blf7my was carried out to determine the effect of increasing substrate co6dj6akop7g9 9lfb f7mncentration on enzyme activity at a constant 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 oac;b * jgn3gm-7gnhi( f reaction of an enzyme 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. The curve mag- 7ba n;ng3*g(jichmrked 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 stuonb dl1pr/:lniquh7bj :n 0 5:dent cut a turnip root into small cubes. They measured approxi bnjpu :nr i1do0lbh:5l/n:7qmately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The homogenate was 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 below. Inp (/6/t4nxm 3wujaem95 vpu ifhibitors to the enzyme HMG- CoA reductase can lowi6pn3aem/tw9 f 5( u/upv4 xmjer the production of cholesterol.


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 d5yf-s kc ;nki 7pc98n2zisa9nenaturation?
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 reactions in the classroom anuegdk8: ve *h2d were given an experiment which demonstrated the effect of tem8u 2kvdeghe:* perature on a catabolic reaction.
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 increasing temp+ ims o9u3ugrphm ff7; iru*s7mk 1f8:erature on the efficiency of lactase activity is test+98 ihs7r7mf mks1f uo prm*u;fgu3:ied. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analys,n) uxakl2n -zing the effect of pH, temperature and gluco2l -nx,) akznuse concentration, as it may potentially 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 continuous need to fiwr)-5c0ia1v wp0. dgwfq hg9u( g0on qnd new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with new technolo qv.(r05ug0d9 wp1wn c fh-0g)wq aioggies.
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 afferr5o l0ozt+y3 cts the rate of reactionorz53o lt+r0y .
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 synthesized+i 9 o5h0 1irjm,8cmh ppsvvh+ through metabolic reactions. Which type(s) of metabolic reactions are condensationm1pmv859vh io 0sp+j +,ihhrc reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can bd7u9c9 rn pz9y76 vbuxt loa:5v7i 2hre measurer 9a7ynlxoh v92 b7ui5:7zv9 uc 6rtpdd.
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 contraspoki(+- l-1 c0e dcuhkt intracellular and extracellular chemical reactions, given one exampdcpke1 i hco +0-u-l(kle 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.