Which of the following macromolecules desl3 8bty:nfcvh41d vp7d- * zisn8ke u9cribe a typical enzyme?

  What type of reaction v 5.uy kut ye)8as;e5gis photosynthesis?

  What is the substrate fo; 5gojvh-ok.e1 z: sijr the enzyme lactase?

  Which of the following stages of cellular resp7tu )dfhb r30liration takes place in the cytoplasm3ublf70thrd) ?

  Which of the following would not be usefun) zraj.0 d9 dl+r,)iq p(yaidl in determining the rate of an enzyme-catalyzed .ndjy9a )q (+a,i)prlrdd z0ireaction?

  Which of the following processes may +4.1t pwjzf z5g+lngqrg2bq) be described as catabolism?

  Which of the following statements is best depicted by the 9y 0q.x vu8qu xzxmzo+f; m+r+figure below?

  Which statement about enzymes is not trb3*tqj:di x4 vue?

  Which of the following graphs best illustrates the relationship7/2 f8hj vjt;u2-knw cxzu yw( between temperature an-(xjck2ju wtzf 8nyw/;v 27hud the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of ed5u9ez83kor substrate affect enzyme activitye3dozur 598e k.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is piak (2g6a0/c2c6h u ta bj.ena series of enzyme catalysed reactions. A diagram outlining thcjgit(e ahpk0a6 2cn62bu ./ae Calvin cycle is shown below.

The image below shows the catalytic site of an p q/5i3cccf7r,gq u, kd+v /9ohj0owzenzyme. The substrate is shown in black and is bound to the aw5qv+r/,hic 0u p9j do3 ,/k 7czfcogqctive 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 des1te+w7r agd*ln y4i28 .zewclcriptions of the enzyme catalysed metabolic pathways shown below? Letters represent various products of indi8dlgtrawz2w y+i 4c* e. 7eln1vidual reactions.

  Which of the following describes the role of inih8 eqhxo +:h.hh f4/x6u 8q0pqimb v/hibitors in enzyme-catalysed reactions?8/bh06 u v hi iqofehxmpq8h/.x+qh4 :

  Which of the following correctly descm ek;ji( ) qohy5c*e0dribes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple stepl4dd /3a2 kxtzuv/o1 ms and multiple et mk1//ld43uxo vda z2nzymes.

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

  Which of the following best descr r)19jv xxlq+ha+ifcw68kg 6 nibes the inhibitor in the image below?

  Which of the following statements are true regarding regulation by end-produc k jgo 06m0v,yfct7s5gt inhibitionycmf0,6 oj5tks0g v7g ?
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 3 3.y3qi pqkl l; q7*ihd(0tjh;c 6njfo vul)nlysozyme enzyme. The darkened structure in black is the substrate and i3 ;jhl u6( ji ktd7vollpiqnf30.nq hqcy);*3s bound at the active site.

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

The equipment below can*k:26+hgm2 1tk/lojb 2 c pv 4tlkn8ytbm:y sl be used to study the effect of temperature on the activity of th*t+gk8/62:yvt2:kl1 nbyc 4skhpb lml moj2 te 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 enzymes interactjg *2x p;bo-y whmp8 hto;cf39 0duhu, with substrates to catalyze reactions bu9*td mx8po;3f;hgp 2 wco-u, jh0hy?
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 cataa* g4)8x egve/wd4 dyl1i c8eglysed reactions can be measured.

  How does denaturation change the properties of an enp 0*jsl79t xlkzyme?

  Enzymes play a role in catalysing reactions. Which of the following tt3f zfwzl9 7:statements are true9lf zt3tzf: 7w?
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 characteri:*r4 iro lkzj vf(d rvk a7-5a:cdu2(xstic that separates mammals or endotherms from ectotherms thatk flzr5i uvcv-k7*a(r:j(:2 a4oxdd r have fluctuating body temperatures?

  A metabolic pathway that converts threon0 i5der+2oua line 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 enzyme in the pa5u0leo2r ad +ithway.
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 u58s azbwg5 9breaction. What is occurring during the phase labelled section X in the graph? 5bwsg9bu 58a z

  An experiment tests the / echo3*f ut9hg9zgs9effect of changing substrate concentration on an enzymatic rtsf 3g*eu hhco9/g99z eaction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway thata5 l6avv .*fc.kfd0ij converts threonine to isoleucine.



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

  Enzyme A (Enz A) wassk iodeh+38n, immobilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzoihke3, dn+ 8syme 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.j i*0hyf3 knv. Which of the following is the best way to keep enzymes acv 3hk*nj iyf.0tive for a longer period of time?

  Which of the following a*;euly 5* 7 wwaanyg8describes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides iw3 ya3z)c21 +9gf) vnh vrn+tejqwj r9n the stomach. A study was carried out to determine the effect of increasing substrate concentrationa2cevfny1+w zj 3rnv9rwt)j+q9)h3g 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 s)bo3 qvvc r5celx1-d9 w3he0j ubstrate concentration. Similar concentrations of chemicjr h5oe we) 33d1lx0-cbv vq9cals 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 awm-36vm fi2 obl6q-ey turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The homogenate o6 wye-q23b-f6mivm lwas 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 iac5br (bh 9 dpka2h; w--yrev5s shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholesta chya-k;5rb pe2 -hr5bd9 (wverol.


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 denaturaln0ox) )y kn:bmv oo40tion?
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 themdtwd)up5iejd-64 e 7u) px2n classroom and were given an experiment which demonstrated the effect of temped5ue- t p4 d)nid2ux67ejm)wprature 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 temperature ip812lhz:/twpzw ( ldon the efficiency of lactase activity is tested. Which is an appropriate dependenlt2zw/dw 8z: (lpp1 iht variable for this experiment?

  A study has been conducted on the l rl1z9pzl 4m+activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concen+4plz ml1lzr9 tration, 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 find new -0casn;e*dz o drugs for treating patients with malaria. Describe hod;es*cz ao0-n w 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 anyy amyu i pls6q0-seg+** at3: enzyme affects the rate of reactiogayspe+tsay0 l 6:3**qm uiy- n.
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 thni)vj bn30q,ucibg dqt56o8l/ s; zi*rough metabolic reactions. Which type(s) of metabolic tl,3jznq b)vnd6gq*iui 8 0;/soc bi5 reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions cann3tolm -ta)c/ ,5+frkl vj +yd be measu dv, yln+k-5 o rtmtl/+a)j3fcred.
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 ut1/r:i* 3h dp,rdfqd, given one example of each type of reaction ,dr3fprh :d1itd* qu/.
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.