Which of the following macromolecules describe and p .n4:8i hmyk74*fjhq7ocs typical enzyme?

  What type of reactionj , /-twnurp* l; r3d1hjacr,f is photosynthesis?

  What is the substratef+ye z2ua v:0g for the enzyme lactase?

  Which of the followings;tjya5 /b czjfm78vd 7u 5:ug stages of cellular respiration takes place in the cytoplasm?vz/ 7y7j5a8 um5jgctfds u :;b

  Which of the following would not be useful in determining the ratewl 6mn2jbzrjxj 0, 39t of an enzyme-catalyzedltj ,w2b3zx6r0 jjn9 m reaction?

  Which of the following processes may besrg71h7u: gk aqh)wo2 ;5gtsckc o**p described as catabolism?

  Which of the following statements is best aj )2(w a/a(yzygiw9ydepicted by the figure below?

  Which statement about enzymes is not true? d0 d*4frdc+;tc1hqew

  Which of the following graphs best illustrates the relationship between temp,bbzb7o81 wrterature and the activity of enzzrwbobb 8t1, 7ymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrats yl;lg1g +(ene affect enzyme e+lgsg(y ; ln1activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of en xt at2of9ij6l oa,3c,zyme catalysed reactions. A diagram outlining the Ca2tf6c, l9jti3o aao, xlvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrm4 s;x80q pr 2coiswi;ate is shown in blax;s4r;m2w is0qioc p8ck and is 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 catalysedfyf wi icqlbh+wtw1/) a4oxorw:z50m/ kh2 + . metabolic pathways shown below? Letters represent various products of individuaaibrz/fo w+0 w2+)w5f/ xc:lo4 mqhkw.hty i1 l reactions.

  Which of the following describes the role of inhibitor)t tac tyhq163s in enzyme-catalysed reactionsy6 aq )1t3tthc?

  Which of the following correctly descf1z37xw pp)0fc(y kxl e9gxq: ribes photosynthesis or respiration?

Many enzymatic reactions happen as pathways invxb* ya88hncj r*hyc*3olving multiple steps and multiple en*c*jrh*yc b n83 8hayxzymes.

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

  Which of the following best describes the inhibitor in the imageyf abn 1anh +;xu6-.+kw,wqiu below?

  Which of the following statements are true regarding regulation by end- qqh0k)4xr lzzq-w *bem/5h0kproduct inhibim l0qwbr)* 0z-xzhk4q/eq5 hktion?
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 1oohb;1 (v lq rkh(r w-xy:o)eof the lysozyme enzyme. The darkened struorkq)b(e vohyo1 ;h( x w:-1lrcture in black is the substrate and 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 of temperature on the accs0p3pw0us a0sq8-jp tivi8usap0 - qc spsj300pwty 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 eqb s ,uen1bl4e. qo 4fl1ljn;.nzymes interact with substrates to catalyze reac,ll. .qnb41jeqbuo es14 ; flntions?
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 h uv9 )2zc *cq.e fb+us:yjj:ycatalysed reactions can be measured.

  How does denaturation change the propepw icyfd6h6.hlhi8av /n+ :l)ws.fx(rties of an enzyme?

  Enzymes play a role ic1 qq5f)s9v6mys/m v /xzony1 n catalysing reactions. Which of the following statements are tr1fq6om9/sv yscx1 qz 5/n )vymue?
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 ectotherms7 zi z;vx 1pyjoz1im:9 that haveyizv1 x mi :z9;o1jz7p fluctuating body temperatures?

  A metabolic pathway that conver-mzps-ag1c wto2 84tg7gzx f1 ts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by differengt gmw2z1-gazs 7c-o1f4tpx8t 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 incre8 j gtydhnbv5/b-36tdme lfkri1f(80asing pH on the rate of an enzymatic reaction. What is occurring during the phase labe 0(i/6ed1 -v3ngrfk88b 5dhyttf mljblled section X in the graph?

  An experiment tests the effect of changing substrate concent/nn q(j9l vox3f tp(cxz5 f8-xration on an enzymatic reaction. What could be the independent and dependent varia px8jn3c(f x5 (x lv/zto9f-qnbles in this experiment?

  The diagram shows the pathway that converts thrdf z+bsrzym8hl:1f*5vl.z ane + x( ;feonine 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 4exjp 4z4 xpgiy:ps2a(aix .6activity was compared with that of a free p 46x:is4gz jaixxpa (4ep.2yenzyme in solution. The graph shows the relative enzyme activity (y-axis) 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. Which of the following is the besp0dtu3 ko5kua7t18 ): arqexut way to keep enzymes active f8puk 1 xe3td)k: quoa75a tur0or a longer period of time?

  Which of the following describes some types of extracellular enl .yumm05. oh13mxysak n87dc zymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stod x:m-yk1x;:x- dps0 gj;du tomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant te xu:0gs-1dyd: ptm; jo;xdkx-mperature 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 reacthajb;9)rz c, qion 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 h 9qz;bjc,)ra of the reactions. The 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 studen mv87 4aa0 lnzsdfze3,t cut a turnip root into small cubes. Tv3m,alz az4s 08 7ndfehey measured approximately 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 ikel ,upj a/ -/bg53f 1kqi,hhzs shown below. Inhibitors to the enzyme HMG- CoA reductase can lower i eu/5pz h,lb3g1k qj, ak-h/fthe 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 in+ rtbg6n2z.q-o+tzde- *ns*.p tbi j dvolved 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 reactions in the classroom and 3rxc8iz8 spj: were given an experiment which demonstrated the effect of temperature on a catab j:8x3 8pzsicrolic 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 temperatur4j ;wlosx8c-8 aw/dit xni:p2e on the efficiency of lactase activity is tested. Which is an appropriate dependen28tcs- ilxdw;pow j4na8:i/ xt variable for this experiment?

  A study has been conducted on the af6o, rcac*4c1 k3pr mh2hm0ql ctivity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce h6fh a c4rq 1k0 2m*rpom3c,cllactose-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 continuox0ac.o 4 iw- c/yuqs4q prwq,+us need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with,xauc - w4o+/q.c4 rq0ywi psq 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 affectr v.s g:ity8,is the rate of react .gsi,tr:y 8viion.
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 metabol)z9t,b-0l4 rcbrr pqqe 2wz-e ic reactions. Which type(s) of metabolic reactions are condensap-q zwrrblr ) 2tce9qz-40,b etion reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme c6;cgortqds b5os1o +) atalyzed reactions can be measured5sb t1o;qoo)+ r cg6ds.
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 extracell7ta .u ,4qmga;ii.zc aular chemical reactions, given one example of each type of react;tmu.iiqac47a a g.z ,ion.
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.