Which of the following macromolecules desxvch woz5.v/ ;cribe a typical enzyme?

  What type of reaction is+1xu9buj;6:kc gb rm, py2cqn photosynthesis?

  What is the substrate for the x vqu)coi7 /cka-9:,eqzx i0s enzyme lactase?

  Which of the following stages of cellular respiration takes place iq5qxe2m7psqjj37 i( r n the cytoplasmmj q3rsepq(7iq75j2x?

  Which of the following would n +;s2hogasj1x ot be useful in determining the rate of an enzyme-catalyzed react a js2oxg;+h1sion?

  Which of the following processes mayyu px7(k3xxfc:. k f*s be described as catabolism?

  Which of the following statements is best depicted by th(ib.f y)dsv. he figure below?

  Which statement about enzymes is nnp oazf 3y-::iot true?

  Which of the following graphs best illustrates the relationship between tempoaqu+ c 8dqxrl*63/.un g2mdrerature and the activity omr 23cqdux8.dn*ul6ra g /q+of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate 34jz4bk,m-ksh *xy he affect enzyme activy 4 hek3hskzx-4*m,bjity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a ,w+ j8o2kd 4kj mtp/pfseries of enzyme catalysed reactions. A diagram outlining the Calvin cycle is s,jkp jkm48pd to f2+w/hown below.

The image below shows the catalytic site of an enzyme. The substrate i( lmgb8k,:c kcs shown in black and is bound to the active site.,c mk kcgb:(l8





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 f u+ kjk 8s+pzxrzw:0g;;/k gxpathways shown below? Letters represent various products +;gs ugzrk/ kkw+ jzx8f;px 0:of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed reacgpirka m*; cl/t zazk e2 )88i/dh*0j+a egg+igmz a zt/a8ig g/ dk2ph*e) iri;+e*ackj8+l0tions?

  Which of the following coryammzxep;zu;41) pr v/r ys( j2ge-1jrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathwa6s:mi h+8wlep 6isx vpib:2g, ys involving multiple steps and multiple enzymp 6ls+i:6 :higiw2,m vspe8 xbes.

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 belolkvaq j. vc+h8x.zyt/yh) z(:w?

  Which of the following statements ar2e wvr-0-hjq . nvz8sme true regarding regulation by end-product in 2wsejvn-hm8qv- 0 r.zhibition?
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 dak 5 z1c1g0xgc57srfl drkened structure in black is the substrate and is bound at the active sixc1 1sg z7kg 50fcl5rdte.

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

The equipment below can be used to study the effect ol)wy n+y)4 ls;l homf*f temperature on the activitywnoy +4)h*lm;yl ) fls 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 h merajt 7.-w8wafo k+-spv;6oow enzymes interact with substrates to catalyze reactionafo8+v --7 awj .6wrk mospte;s?
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 rea 2a ga2tt-r2ecctions can be measured.

  How does denaturation change the properties of an enzyme?gs)xkf3 gtb.e)7l2 4z1 ghf1ua6eifd

  Enzymes play a role in g sw+8;w.92lm cu lsfv+vq kp8catalysing reactions. Which of the following statements are trusms 2uwl .k;9 g+pflcq8 v8v+we?
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 en:hft nn ds319s(kb0ijdotherms from ectotherms that have fluctuating bodtnd3jh9:f 0 sikbn(s1y temperatures?

  A metabolic pathway that converts 9u1uy/nq9 vowucu5k6 threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is coykcu uq65 nvuw 991u/onverted 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 bp jdg*yzc.hj/g1 dgd2 9 )pr,on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in thdp9gjd/y.gzbcg, )p 2r 1jd*he graph?

  An experiment tests the effect of changing substrate concentration k+ jdh r /1cr.*b lu-t7 sbogj(nqm(ym7l,7vxon an enzymatic reaction. What coul(mqy*xlducm7b r71jtl -,v jhk7 s+( g/rno.b d be the independent and dependent variables in this experiment?

  The diagram shows the pathway th pw0x841mj4) /k8lfufj icd uwat converts threonine to isoleucine.



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

  Enzyme A (Enz A) wasu.z4r j zfp 8e;mdu 8zc)w oftoc(/+pi5xg5q7 immobilized on a matrix and its activity was compared with that of a free enzyme in solution. The grtq +c 75.cop xezj/u8gpd i5)zumo( wz8;rff4aph 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 beyll so:gin9clrav6 ;b7u;(1 qst way to keep enzymes active for a longer period of 91sin(a;6:vlb; llugco yqr 7time?

  Which of the following describes some types of extrs3ylilk7l (s,: v9kxh0 ;r tdkacellular enzymes?

  The enzyme pepsin hydrolyspa2yyb.dh3iyguu2ijo(b . 6.es proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme b.26y . 3 uhajybd( i.o2igupyactivity 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 increaswpglan5xk 4yu6,;ts, , 3v4ppyqjm8iing 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 cq4v;n5 si8,3m6xlwpy4 pt y ,,agjkupurve 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 turnid)2 k/elf e jlta/n)r(def(b*p 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 was filtered and the liquid extract was stored in a test tube at room te*/ja )fdrell d/ etbf)2((ekn mperature.


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 ogiuv1u* b5 i-below. Inhibitors to the enzyme HMG- CoA reductase iug uv1ob5i *-can lower the 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 involved in denaturatio0z: 1 yez,n*.jx2v0d9hlofes eljd 0hn?
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 met.gy)zkp 0e z*n-+ k jgjhaj(7eeu1827dads kc abolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a ) *z7 zp(2gj ya+ndk 8d e. 1kcuj7keh-ajeg0scatabolic 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 inc +the*elgx,d.reasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for thi. xg,eh+* eldts experiment?

  A study has been conducted on 46ces5i o/i z(s1ax sbthe activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose conb1/aixi6 z ( oe4css5scentration, 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 zp.+r3 fhol vn2r-mfcf9y- v )drugs for treating patients with malaria. Describe how anti-malarial drugs are being difrocfvy -m f-n3)rph. vzl+29scovered 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 increasingdhhs 6- j, t(xoad1xc- the concentration of an enzyme affects the rate of reactis-d ox6t1c, -h jahd(xon.
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 synthesiz cdt,o2mq-u 9ted through metabolic reactions. Which type(s) of metabolic reaqt- tc uo9,md2ctions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactii- 4d3rt kh3n) r dov:y5qtiz7grv8i7 ons can be measurgqrvo75 -hyiztri:rn)3d8idk 3 v 7t4ed.
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 chiw d k1lu8wu1)emical reactions, given one examu8l1dw k1iu w)ple 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.