Which of the following macromoleculobxsr4ww+ 808 4uvoj ees describe a typical enzyme?

  What type of reactioftbog1jd g la51w/.b157 vqhh n is photosynthesis?

  What is the substrate formt4t(o0:er uk)kd kr: the enzyme lactase?

  Which of the following stages of cellular respiration ta 4e; :mqz2 0u.:purhqtj upuhk(*.dio kes place in the cytoplasm 4j(u rut:;up0um.: he2zko d*h.qiqp?

  Which of the following-ap,hvhth seoq25x )/ would not be useful in determining the rate of an enzyme-catalyzed reactio hv/), aotp52shexh-qn?

  Which of the following procesdpco 1av (4.xeses may be described as catabolism?

  Which of the following statements is best depicted ut;,+qe pthq6by the figure below?

  Which statement about enzymes is not tr: 2 7ypf4tmxouue?

  Which of the following graphs best illustrates the relationship between tem zco225d mtg7:ag zyp1ir0x/u perature and the activ2og0:5p ymu1czd2rixazgt 7/ ity of enzymes such as lipase?

1.Sketch a graph to shonr rbj5*((rm9 *h1bgpr kzjm- w how increasing concentrations of substrate affect enzymenj(rk-5h*gr(*b zr1mj rm9 pb activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactlsxlk:p w 2a-6ions. A diagram outlining the Calvin cyk :2 -pxsl6alwcle is shown below.

The image below shows the catalv):e7dk5 vxutytic site of an enzyme. The substrate is shown in black and is bound to the active uk5)e tv:7 dvxsite.





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 deby1z: 8gc(hch scriptions of the enzyme catalysed metabolic pathways shown below? Letters represh8h1zcc(gy b :ent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzymsy no5e7eh,0nvae3*fzaha8e d(mn /+weg83 pe-catalysed reac 8ea5 3e+pf7nosnm83h dh*wvaeyng( / 0zae,etions?

  Which of the following correctly describes photgwbb1)qlct gb p. 7a7ai 3r:x:vx6s0bosynthesis or respiration?

Many enzymatic reactions happen as pathways involvingm7u( 4vyw y.cw multiple steps and multiplcv y(u4 w7.wyme enzymes.

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

  Which of the following best describ7 sh -yc7mo+s pahh4r6j2sx ,dqm 5is+es the inhibitor in the image below?

  Which of the following statements are true )0anmtp6;nux regarding regulation by end-product inhin0)mx; u tna6pbition?
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 da w6 lc/cs+2e3;cloaqirkened structure in black is the substrate anosw /lc c2ec+6l qa;i3d is bound at the active site.

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

The equipment below etrt)np pw+ q; /efy )*wv1ra 0h.y-eut8y i)ican be used to study the effect of temperature on the activitiw 1fyr;p ey))i*ewav+y/t te.r)un p-qt08hy 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 statements describes how er/6/ xhsyyyl 2 77ixgxnzymes interact with substrates to catalyze reactions?6i2y7r xlsx//xy7g y h
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 catgn t/wsm 5e*1zalysed reactions can be measured.

  How does denaturation ik k g/9,a(q+lmcdl v-change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. :fsmuh;9jy;x19s di*i9ko trWhich of the following statements are ts;y9 91uh; t9jdrxkifo*mis :rue?
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 separad(z3(p jfxnqs.4-zx c tes mammals or endotherms from ectotherms that have fluctuating body teq sj-n3 z4dxcxfz(.p (mperatures?

  A metabolic pathway that converts threonine tohz5mep 1m *z*j the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially *z 15*ehmmp jzby 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 effect of increasing pH on the rate of an enzymatic rea)qoygwh)x)(;nnk etrh h ,0u( ction. What is occur(qyr;og)h )k t)x n0,hnuhe w(ring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentrllcjka/:74 e nation on an enzymatic reaction. What could be the independent and dependent variables in tc/ 7:aljlne4k his experiment?

  The diagram shows the pathway that converts threonine to isoptb6qt/ h/v9w)g;p8 uzaz s4gleucine.



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 was compared w3 a ;i.q pm5f- lce9/hxeocel3ith that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with va ao lm 3ce9hxq3/ipel5fec;-.rying 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. Which of the following is the bestk2jtq)b*ayenj3c1 :y x 2s o3j way to keep enzymes active for a longer pb*:a on 23yjk jjsq2y1) tex3ceriod of time?

  Which of the following describes some types of h ig 5wys+;vg,extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release pgg2 m(37(zj* sgcpexl;*x rdpeptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activitygx7 gd(j*s 3 pe(zlgcx *2pm;r 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 of resdydy:w pp ;l2,i2r )nd3)n ynaction 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 marked A coincides with the activity of the enzyme with nop,2 iyy23 rn:dpd sdn) ;wl)ny inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a 70/wz p*:n g7dk0ajqrwj 5oobturnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to h zr0:jnaow*0b7g5d/wkqp j o7omogenize 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. Inhil4 hhco -b7cw:1ygku( f)thm6n g c62mbitors to the enzyme HMG- CoA reductase can lower the production of cholesterol. 6mwyg)6hkg cc hhm7n cf(1:t- u42lbo


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 invsbuy/fq: g) q*cc( -: e3khur8jlmy 9volved in denaturation?
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 i3u0;f/g tpooreactions in the classroom and were given an experiment which demonstrated the effepft;g i/3ou o0ct of temperature 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 temperatuo7 uzt2,t8 wmvre on the efficiency of lactase activity is tested. Whw m 2vo,7t8uztich is an appropriate dependent variable for this experiment?

  A study has been conducted on the a z35wzxh3rpc ,m:.ggo ctivity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentrat g3.pg:xh zr 5,mo3zcwion, 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 t+,4av5c:tgsalv c g6uev5r)to find new drugs for treating patients with malaria. Describe how antvevs,ug4 ta+5r6vct :5)cgla i-malarial drugs are being 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 concentrl58h zh+erq2a ation of an enzyme affects the rate of react8zah l h25er+qion.
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 through metabolic reactions. Wz 5oka3h4fp 6chich type(s) ok3 a4c6zp5 hfof metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cataem5dx( yp4v(q rk.l(a lyzed reactions can be measurx l 5y(e.kmv(p d4aq(red.
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 chemical reactions, gi)*uconlm (z9r8 (eg lcq,b-te ven one example of e8geu9bc-qt l (r )c(mn,l eo*zach 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.