Which of the following macromolecules describe a t2ma) nq 7i uga7c:t d1qvmo(a*ypical enzyme?

  What type of reaction iuil*b5vgfd7kzo g4 01q c 6o;48.ens qbyyo v7s photosynthesis?

  What is the substrate for v0v kn;,pqi2vto.*tj the enzyme lactase?

  Which of the following stages of cellular respiration takes plae0+6daw ;w g9jm6 c ,-ktjwqz6fytc(t ce in the cytoplaswm a6t0 9gj(c+dqz-ckt yj,;t6f w6wem?

  Which of the following would not be usefci ibcrhl*f; z/:)(khul in determining the rate of an enzyme-caibki* ;hcczfr(l/): htalyzed reaction?

  Which of the following proc.4t2xc jjc:/ljzy gp9a p8i9xesses may be described as catabolism?

  Which of the following statements is best depicted by mn3 f7t0b(vdlneb6: pu( d,skthe figure below?

  Which statement about enzymes is nof(7x52 l x)ko orn-uxow*womtlz 3 j47t true?

  Which of the following graphs best illustrates the relationship x+ vdal)4ll1tbetween temperature and the activv ll at4dx)l1+ity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substx)j 63sogi0n qrate affect enzyme axon0)gsi 63jqctivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enztuz9rcs et)4q 5w6lz-lr p;d(yme catalysed reactions. A diagram outlining the Calvin cyclez;-)9sle6uz r(4tc w l rptdq5 is shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown ifj(6z vq/j8ownn :ku)vph -y( n black and is bound to the active sitej woj 6p/h :(k(-y)nzvqf8nuv .





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 t t*8o.lese*vo r6nb:l3* av nthe enzyme catalysed metabolic pathways shown below? Letters represent varie.eta o r*nllbt*3osn6*v v8 :ous products of individual reactions.

  Which of the following describes the role of inhibnm hap 1j8cd+5 k14lrjitors in enzyme-catalysed reactio4 hm11ac85drnpljj k+ ns?

  Which of the following correctly describe;2uwrmj)atn(yn+ 6;* y2va 2b y s todfh5mfl-s photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps xt1roue:4syo/e e ;e3ecd(x 1and multiplur x4ey:1et seco;oe3/x 1(ede enzymes.

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

  Which of the following best describes the i ,hr:(w38w 3 upu angcriy+)wsnhibitor in the image below?

  Which of the following statements are true regarding regulatixbdhh1c;( n65s8 9 vngcpx(fcon by end-product inhibitn;8(h51 gxnch (x9bvd pfscc 6ion?
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 omx zop6j r53q+f the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the acti5rp+j6o zmx3 qve site.

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

The equipment below can be used to study the gy2p1 ;ulax8 wr .9hkseffect of temperature on the activity of the enzyme amyly1;a. lus29 8kgh prxwase.



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 in un: g v8n,v74lx i7h43smtphsteract with substrates to catalyze rea4l8xn7 i pvts:hhnmv,374su gctions?
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 c9n*l ij psv1pw4bmdgvw87 4q 1atalysed reactions can be measured.

  How does denaturation change the propertc q+ np/5+ p8twu)iiu:6d u,hp6tsz hsies of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the foll a;t jnsct0.(iowing statements are tsct;n0t(j ai.rue?
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 p6 2inhqsw jj y.,0tmb, )e(sgfrom ectotherms that have fluctuating body temperaturqs,gtynibp 2ewj,j msh0)( 6. es?

  A metabolic pathway that converts threonine to the end-product isoleucine +mql :6nep;uaconsists of five reactions. Threonine is converted to various intermediatu;+am:lp qne6e 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 enzymatic reactioi( 8)olu1,y x3xli rjsn. What is occri ox)l(u8 s lij,3y1xurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate3tanz8b k m-991 6 lqyrzmk,bw.b;2bmui(hbm concentration on an enzymatic reaction. What could be the independent and dependent varb3,hmya( -utrmq;l 8wnb2bb 69z bikm k.m z19iables in this experiment?

  The diagram shows the pathway that converts threoni6 ) gm :e8p3yanpj,decne 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 activity wa/ rtkh7m i/hl)s compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis)mh h/i)lk7/ rt 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 4oij dz(58 tqc2axl g9the following is the best way to keep enzymes activg9 x dj2(i4lqo8tz5ac e for a longer period of time?

  Which of the following describes some types ov+;bw5gbft o6f extracellular enzymes?

  The enzyme pepsin hy1 .u )qx,+:wwxhwa8qstg:f op drolyses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activ :8u+xq x:.otf,gaspwq) wh 1wity 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 enzwkcl3 bzqm5(cv;) a (tyme with increasing substrate concentration. Similar con3lmkqtc()c(;vz5 baw centrations 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 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 student3t8skf -a yz)x cut a turnip root into small cubes. They measured approximately 5 g in a weighin)f y3za8txks -g 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 reduct :d ; /8/izizeut5hd2-zs vcmjase can lower the prods j zt2 czuzdhmi:ve8/i5/; -duction 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 invol jur wqms08:0uved 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 classrooym)*(qc7yh.ib (dm pwm and were given an experiment which demonstrated the effect of temperature on a catabolic reaction*(7 iyypm)qw .d b(mhc.
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, thewxvfd e7z rin5a ,d8m7./ns+ y effect of increasing temperature on the efficiency of lactase activity is tested. Which is wn7/mr7vy.i5an s8 dxze,df +an appropriate dependent variable for this experiment?

  A study has been conducted on the activity 2ludr2m.2w6 noiui 3n mcl.-tof a specific lactase (Bg10), analysing the effect 2ri2t m d un.onil-mc.w2 6u3lof pH, temperature and glucose concentration, 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 drugs for treating patients wi gf3bx0jhza 5;ea. o.fth malaria. hf aa.xefo3gb .50j;zDescribe 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 concentrati4cd3nuw2 x*ymz-t,;gbu4dxf/0or l ron of an enzyme affects the rate of reacti0 ngb4l24fw3*zd;o dt rrxcuxy um -,/on.
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 rea/am zdk +p.e v w9;lgh:a6xb;actions. Which type(s) a;.d 69bgw z;pa/lhm:ev+a xkof metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different adf x.+s2r .je4vvr q6ways the rate of enzyme catalyzed reactions can be measurq. rer4ds6v jxva+.2fed.
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 reactionnz 8hhzfp+: qwfrn++ 4e05ev+;n vxeus, given one example of each type of reaction. nhfqhe8 e;5+0v+:wx+n npuv r4+ezz f
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.