Which of the following macromolecjx 30j xu-*hduules describe a typical enzyme?

  What type of reaction is photosynthesisp cdh 6je hc*g-7rvu)7?

  What is the substrate for the enzym0xs.x nf4x (eyw6w n.ue lactase?

  Which of the following stages of cellular respiration takes place in ld+3y7k:vz yhmy6ix +:wuy c/the cytoplas7:y3xc+vh yi/m k+d :lzu6ywym?

  Which of the following would not be useful in determinizha 5)o4rlbx:s6b 5y nng the rate of an enzyme-cata4 x5 s6:yn)l rzb5bhaolyzed reaction?

  Which of the following processes may be described as catabp*vv cadnkc 3y z6*98aolism?

  Which of the following statements is best depicted by thef 4z j6k0: yb*dxipl.p figure below?

  Which statement about enzymes is not tl. /neus5,0 gg wifyr)v45lplrue?

  Which of the following graphs best illustrates the relationship betweeywifipu,7x9,v 7b-ll n temperature and the activity of enzymes such ai7pxb 9l w7ilu,y v,-fs lipase?

1.Sketch a graph to show how increasing concentrationsn:leum. 1nk-uew gk28 e:c8vy th29ix of substrate affect enzymghwx 9eu nk2 :.8nkec8iu vtyl2em-1:e activity.
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. Aamoi zx*y0 7ypm)8jt. diagram outlining the Calvin cycle is shoyi o7p0 maz*txm)j y8.wn below.

The image below shows the catalytic s+5wc0 6rtyrhabt;b6:sp1yca ite of an enzyme. The substrate is shown in black and is boun6rb +s160h acatytrwp5cb;y: d 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 p-, .z.8 bchzo5 8xiiitpfiwdp- nbq60athways shown below? Letters represent various products of individual 06b- ic pi8 n,qw pbzt-i8zhxod.5.fireactions.

  Which of the following describes the rol 6v3 1 *)opl-tbrvo uae4zizy4e of inhibitors in enzyme-catalysed reactionsvro4 pa1i 4*)yoe lubz-36vzt?

  Which of the following correctly describes photosynthesis or respirkycz:3 .6 kmqyfdm k i24c: .dfty,(zfli*7ns ation?

Many enzymatic reactions happen as /ez+vak -*m9knan bg.h9 i19v7nzyix pathways involving multiple steps and multiplehbnay9 eig zkazx-1+nvm9*7/9nkiv . enzymes.

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

  Which of the following b jpx2(/g 6uuinest describes the inhibitor in the image below?

  Which of the following statements are pe, lq/ bjh)k *0 cwby)5to6ewtrue regarding regulation by end-product inhi6 ) l eq0bjt,bwcp)w5*/yko hebition?
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) / 1j(:fo v t7i uzmhswae-l-nh,vz)d the structure of the lysozyme enzyme. The darkened structure in black is the substrat v7u)n/a:t-hde1l f smzhjo ,( )iw-zve and is bound at the active site.

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

The equipment below can be used to study the effect of temperature on the aoa k7j,kk ia*8ctivity of the o kkk7i8*ja a,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 interact with subst ec6r pds4 ud-z5gnk(+rates to cdp6 s+k cg4z5-urne(d atalyze 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 be measured.)e4 al;4m6d1zywxn8 cgxk3(gmm (u go

  How does denaturation change the propertie2 jrl,(rn-pvo 0q bh0as of an enzyme?

  Enzymes play a role in catalysing reactions.vbotdux r-j3+a7lm*. Which of the following statements a*rluomj+ - 3da v7.btxre true?
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 lvqp*jg9qx65 separates mammals or endotherms from ectotherms that have fluctuating body temp9vqj gq6xl5p *eratures?

  A metabolic pathway that convedhyi .a6d+wstu. (ma5rts 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 enzyme6wah .ym+(sudt ad. 5i 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 ofzkmtil44,aym +dtxyjnw7n6 z 02 hq-7 an enzymatic reaction. What is occurring during the phase labelled section X z0lnmyiq- z6+,4427 wmxtytaj 7 hdknin the graph?

  An experiment tests the eff o81ufut-kzg: ect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this exog z uf-8t1k:uperiment?

  The diagram shows the pathway that converts threonine to isoleuciy5q2y;pg,m hs f .gk1cne.



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

  Enzyme A (Enz A) was immobd3-)fh fuebi phg g2 4axi. ie3:qmh55ilized 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 f hm)hug2x-35q5i: i4. 3bdefgep iahpH (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. Whichvh/1) +vg v xtj86rl)e+xamwn of the following is the best way to keep enzymes active for a longer period of timenm6l+ 8hvv)/ aj1vx)wg+ xrte?

  Which of the following descri jk+p7 vs*/((hptsvbhbes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the sh2o 3s. zez0lltomach. A study was carried out to determine the effect of increasing substrate concentration on eno3 zelz.shl0 2zyme 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 ensrtv3quz v0( h8l4uyp, +xx;kzyme with increasing substrate concentration. Similar cu8l ryptvqh uz3+s04vx,(k; xoncentrations 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 enzmegv5+i-/i .wo; iik hyme activity, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender tiiwi/;5 ge im+v-.hko o 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. Inhibp7 fxv3gfjxn9 ec.1x2itors to the enzyme HMG- CoA reductase can lower the production of cholesterol1exfnjpg.7 x2x39v cf .


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 denp+hd9i72xt:7vp xh3dbs0ro q aqm7-saturation?
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 a q*k86 t7p6w9 wvx7iu bbtii9hnd were given an experiment which demonstrated the effect of temperature on a catatvwktpq ib76wxi * i9h986 bu7bolic 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 tiq,rsoc8 1wnkzb9 o7: emperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variabl:1wcro qzok,8b9 7nsie for this experiment?

  A study has been conducted on the activity of a specific lactasetsgq ug).c i *g12l ;(y8gwqav (Bg10), analysing the effect of pH, temperature and glucose concentration, asq . (g a2v8st*;l1g)gcq ywugi 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 kpbarr3+q9w2w v7 xlj3 8:jcbth malaria. Describe how anti-malarial drugs are bei7 k8+clxwwbq a3r 9prjv:b23jng 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 thez7 5/ jym8 tyqiqg13en concentration of an enzyme affects the rate of reacti5q tej g1inyz 3m/8yq7on.
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 aof:.rj /8r i 7x-xepjbroken down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensatr f7 oxij.jre/8-xp:a ion reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the r) pshgtoo9c5fypa , -+lnrv70ate of enzyme catalyzed reactions can be measuredgy5,p09pn l)t oa -voh 7srf+c.
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, giveg xh1t h: rms56.ar,bgel6l3y n one example of each type of reactior ,l653rsxey61lh.h bt:ag mgn.
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.