Which of the following macromolecules derf3 z6 m(q2;nm l iyojl8,oc+vscribe a typical enzyme?

  What type of reaction is photosynthesis?q7krut 3t;( n1qvvsl )

  What is the substrate for the enzyme lacpka vs pr*-/*9 a6exmktase?

  Which of the following stages of cellular respiration takes pqihn.7h);khqu-j eh4yg4 d x9lace in the cytoplasmjd9hh-)euk4 yqq.nx ;igh74h?

  Which of the following would not be useful in determining the rate of o -:km1jea2di an enzyme-catao ed21-mk :iajlyzed reaction?

  Which of the following processes may/fq2nqrp(awt u +o1*q be described as catabolism?

  Which of the following statements is bes: isla -5*wiut.p6jopdoj 6e*t depicted by the figure below?

  Which statement abouta2: dcq5 mkhb(j8kd, u enzymes is not true?

  Which of the following graphs best illustrates the relationship between temperate ,j49vgh0 fu98upernure and the activity of e,n9e8ejur4 f9 upg0hvnzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate ai(upsa nebcq86v 9g(;ffect enzyme activity. pv(us; i8engqc 9(6ab
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 diagram /; *.i6* td :s-odxlee7l iqh :o/+trena hinhoutlining the Calvin cy e.ht e-sn6hido a;h*:r o/nlx d7*l+iiq/e:tcle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is showx;us*,l m:ohw f3 yb/en in black and is boundeu y *fbmoh,;:w/ 3sxl 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 metabolic pathways shbq )tcs29zu;hu/k-fd*afr w(trrf.*iwb,- g own below? Letters represent various products of individual f,u2i r;sbtt(wqh)f-f.u*9rr bg*ak/zdw c-reactions.

  Which of the following describes the role o;vxsa rfr6/ gg098qluz0(nb nf inhibitors in enzyme-catalysed reac8(0nl9;r f z gbavr0sxqnu/g6tions?

  Which of the following correctly describes photosynthesis or reseq6ve+ ksh:l -piration?

Many enzymatic reactions happen as pathways involving mul8alr:;(p adhz z3e9ej tiple steps and multiple enzy;pzahra z8 dee:3(lj 9mes.

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

  Which of the following best describes the inhibitor in the image belon b jf/0g(cfct-fdsc)5cyt15w?

  Which of the following statements are true regarding regulatpzq)xc s e/xxes) 4 /w)wy3u,y(z eo4aion by end-product inhibu )w 4 csxzqa y/w,)xe(eosx43y/ )pzeition?
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 s3 w7/titx p+uv ktonb3t)02d ghows the structure of the lysozyme enzyme. The darkened structure in black is the substrate and i)3 ktpdub itvgo/t7t02w +n3x s bound at the active site.

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

The equipment below can be used tohv, qc4 c2nt- xbmd c)5,ft)ei study the effect of temperature on the activity of the ent-54eit,cxm2cvc) fn,dqb h) zyme 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 stsb hzmgw j,15,atements describes how enzymes interact with substrates to catalyze reactions? z 5s,,j1hgwm b
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 rwf30o/wzep b h0fn t+-eactions can be measured.

  How does denaturation change the properties of an enzyme):yqo u*qx s+mcdpy:fk:q 33e?

  Enzymes play a role -.1c0iy tc rdnin catalysing reactions. Which of the following statements are true?it10c rd-n y.c
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 characterist;*ay 2zy g4vrg: 2fw: aupy2hhic that separates mammals or endotherms from ectotherms that have fluctuating body temawy22:y;*4ugz yhpr fh2g a:vperatures?

  A metabolic pathway that cs r*negd5, jb 9ofbt(,onverts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzymo(b9 n j,*5rbdsef,tge 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 ryow+f9yyz rc + 6zaip xu*;y;;f( mo;ceaction. What is occurring dur;+*p(co o ;ur9 yi+cyxy; ;wzy6af fzming the phase labelled section X in the graph?

  An experiment tests the effect of changing substzp5.t g u*y59go zo7yyrate concentration on an enzymatic rea yy*pyogt9z5u og 7z5.ction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucinerj +c+ja8o d7c.



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

  Enzyme A (Enz A) was immob:tisomb( kb:6m grvlkktv.b*+5 hp5 1ilized 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 pH (x-axis brlhk1k5i+gv.mp : tmsbt*5vo (6k:b).



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 easilb m3ozeyhzv* uhn-6+4y denatured. Which of the following is the best way to keep enzymes active for a longer period z-ue6h+y3n z vo4 h*bmof time?

  Which of the following describes some types of extrzc m e;m.+iw-wn *ofv3acellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach4de,lec n18hw . A study was carried out to determine the effect of increasing subee cwnl 418,hdstrate 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 rate of reaction of an enzyme with increasing substr.9 mbtsct6e* bdy2x5 oate 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 coin b9*.c25tby6o xt edsmcides 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 c j*w*b /aelvdc,s2dmp0z tk.+ ubes. They 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 ew.z ,s*db*d tpmjl+0veak /2cxtract 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 i:h:vvx4 lpu, ms shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the production of choleste xv:hup, vm4:lrol.


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 involvb1 ,cn l k14hsi6vbbn/ed 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 were givr5sylp7b80q m v2k 4dven an experiment which demonstrated the effect of temperature on a cataboyk 25dm7 4plr80q vbvslic 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 ef.i3kk3 -bkw nbw-2esv .wbe8xfect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this exki8sv3bw3 2ex -n bw .bk.ek-wperiment?

  A study has been condu10.qhs r fog2zcted on the activity 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 lactose-fh1 q.rzfo2sg0ree 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 continuoqmg3g( wwncl. v2,58pyjh a :wus need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with new tecnwy:cq .gw5g3h,w2pvm l( 8aj hnologies.
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 :b.x l5 f)nh*g mxsxc.enzyme affects the rate of reactiogh*fx x) .sbx cnlm.:5n.
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 throughfw6d)of gs(-b metabolic reactions. Which (g)sf- bf wo6dtype(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways frtst c;2rxq.tctp/n3/y : : 1 kzga/athe rate of enzyme catalyzed reactions can be measured.;.:rqxt:t1c / np yfsg/zttkaa 32cr/
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 intracu d1jw*u5c 0cl5guy; fellular and extracellular chemical reactions, given one example of eac w5 uccujyfg;05 1*uldh 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.