Which of the following macromolecuepfn ;l lc3c*/les describe a typical enzyme?

  What type of reaction,juyr 6oi0ca, is photosynthesis?

  What is the substrate forvw9h1 fsa byabii(i+b,kk2 t j i*;5h4 the enzyme lactase?

  Which of the following stages of cellular respiration takes place rp/h r bl,8 o0ni,av(nin the cytoplasn / ,iaprvrh08ln, (obm?

  Which of the following would not be useful in determining the rate i/2z n,zl lzhaw4/p4gdw8 1f bof an enzyme-catal4izb f8/ z2h4d zla1wg p,wl/nyzed reaction?

  Which of the following processes may be describk: ,;,*(wgou8p wd fnefhr6 cl9to o7qed as catabolism?

  Which of the following statements is best depicted by the figure belzutg+;tcr m, st7ml4ym.v h47ow?

  Which statement about enzymes is nohmab(kqz ;ln h-c -q82t true?

  Which of the following graphs best illustrates the relationship betwcj-yw3 ;(j .4ha0gvnxpo tkl*een temperature and the activity of ejkxah(tn;0*3wy jgl .c po-4vnzymes such as lipase?

1.Sketch a graph to sp 04auhxnxz mbuvp,1 -0;t*lqhow how increasing concentrations of substrate affect enzyme activi;*pnzuv- 4qxa th0xpm 0lu1,bty.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactions. A di + 0kynz2kc,yem- g3vmagram outlining the Calvin cycle is shown belomeykm0k c3+ v,nyz g2-w.

The image below shows the catalytic sitr/3 pi+5pudu)jst7 ))k uy hbu 1hrm;be of an enzyme. The substrate is shown in black and is bound to the acp +)ub)tur5;u3 1 iyd)/h7bujpkhsmrtive 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 metabolic pathways k- ckr/ qbn/xf) zof55 6no zorqf11l;shown below? Letters represent va zqc)1-z//l 6bon51o;xrqf kn f5 ofkrrious products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-yr)h,xj pqh 6:ioz(b 5catalysed reactionso:j, pir 6(hz yx5qbh)?

  Which of the following coe6ogw 1uaxdv -; 1r9ugrrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as patq/n9k ;cz z +0iuuei,thways involving multiple steps and multiple enzymesze+i;,tukz0c qni/u 9.

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

  Which of the following best describes the inst r lv28+nh2n 3wnfsxwj p,48hibitor in the image below?

  Which of the following statements are true regarding reg)9iqvrn r +nbr9my +.dulation by end-product inhibition)m+ninqrvy . br9d9+r ?
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 st,8a e0ftmc;xg)1d 3bm r,jstp ructure of the lysozyme enzyme. The darkened structure 1, 3,rexatj)fsg8; cp m0bdm tin 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 dp)fx)ns 3opd2/ s mm, ral+k1 qp+e7lto study the effect of temperature on the activity of the enzy1n3+spd)o kdarq2p7 e mms,)/f+l l xpme 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 htavp l9pq 56 -scfj 4hdtzkf,::u3b;statements describes how enzymes interact with substrates to catall9u btv, pd3:f5hqs6 -f:zpck4;th ajyze 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 catalysed reactions can mu3dxj5j1cc 4pvt (: 7 xbsdx)be measured.

  How does denaturation change the .z1 fop+wi m0qproperties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stat4 z:hr(fgtjj18hq3 ph+ ef(x cements are true(hzj(fx3p :4+ jh1ce qg8 htrf?
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 frzs6dm ;ax j f1gzg*cy46,np 8dt5dz,uom ectotherms that have fluctuatingxs*,1 d ddazg4ujp5z6mc8 n;6tg f,zy body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucineq bbhr/o5h7r/ k2vp6b consists of five reactions. Threonine is converted to various intermediaoq//7hr pbb6k5r 2h bvte 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 effect of increasing pH on the rate of an enzypdk4l*l qkk7j1n(a r 1matic reaction. What irlql 1dk ja*p(nk417ks occurring during the phase labelled section X in the graph?

  An experiment tests the effect of chan morol3x k4h74ging substrate concentration on an enzymatic reaction. What could ol7 mohr34 k4xbe the independent and dependent variables in this experiment?

  The diagram shows the pathwazbf lt* ;:h7n vojfwep6.7(k fy 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 immob+ip( / g,tzy0x6qgd cnilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying g0dz txpq6 ,(g+i/cynpH (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-1hoo spu)5 j3c2ur*f aolh6b following is the best way to keep enzymes active for a longe c pl)u*j25ru16hfshb-o3o aor period of time?

  Which of the following describes some types of extra vmfm*8 znl*l)cellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides i2epuf6 lj j hs4ju4:qh54 rn:en the stomach. A study was carried out to determine the effect ofp42jq4eu:6rj:4 ufhlns e h5 j increasing substrate concentration 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 rao yc2rprc4yw)( 6htmmw;f2q 0te of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicr)q p rmwy0;o 2 46c2ft(ymwhcals 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 no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a turnip root into small cubezo anhk5 -cj*.ew 8-hbs. They z-cen*a 8hkowjhb-5 . 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 is shown below. Inhibitors to the enzyme HMG- CoA redubr 8o ufm+86v: amacq;ctase can lower the production o+6b8 rfvcuammq ;8a: 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 denaturation? a x s+)6a5ifkq
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 w mvs*42jz dndfn ;8auo 9(z7boere given an experiment whi(zudvjms d789;onfn4 a o2 *bzch demonstrated the effect 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 ir.17 nqmtc2 ztemperature on the efficiency of lactase actmc7 2r ni1qzt.ivity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a speciwok i-h4in1 1dfic lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produwi d ok14-i1nhce 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 find new drugs for treai5ufrb81 0upw vfx bc( +10yw*rt +ckgting patients with malaria. D8f x 15 w(r0b gcuw1+rbctuy*p0fv+ikescribe how anti-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 concentration of an enzyme affects ta,yb d-cwy(z) +x*yrz he rate of reac b,zrxyy -d+ *)ywc(aztion.
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 reaction xx,/t m0l99c go:xuebs. Which type(s) of metabolic re0c,g:txe9l/ b xxm9uoactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzedi *dw*bw;j5j2azg we + reactions can be measured;z* id w5jga+j2w*bew.
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 reac*f 3+7wmtqyf h2 kxv*h0 *sxqbtions, given one examplev b+*fh m0t*x2sh w*37f xqykq 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.