Which of the following macromolecule/ 2cxk* ebya)os describe a typical enzyme?

  What type of reaction is +ys:tfd1j8)w0xjgc q photosynthesis?

  What is the substrate for the enzym 3qj v)iq-o+zje lactase?

  Which of the following stages of celluks.rvm e8 d,2 m3+. uzszdc*grlar respiration takes place in the cytoplasmd2vz,mczr.em.r+ds*u k 83sg ?

  Which of the following would not be useful in9;hcl;r1f 3gfpdkyk)z6 zi s( determining the rate of an enzyme-catalyzed i(pl6hf ;3)cz z1;kgk ryfd9sreaction?

  Which of the following processes may be described acue)(7e- (ac: pal ) wtsbso;qs catabolism?

  Which of the following statements is bdi 68 - rg s.j8gow/xp(azsif88hgmb3est depicted by the figure below?

  Which statement about enzymesra*+x7 -28pyf wgumo (uzducr.q-h 6c is not true?

  Which of the following graphs best illustrates the relationship betwee swb90x dsdxh z:z+ :wdf7f9o+n temperature and the + zd::fdxxf9bd9s70wzswo+hactivity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of k 6yzk:91 wn n:l8zknnh28kd hsubstrate affect enzyme1znkknwn9 :dzl:8hk n 2khy68 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. A dia6 csl2sub bwu pn2w-6/gram outlining the Calvin cycle is shown below.bc6ulbsun 2s/ 26pw -w

The image below shows the catalytic site of an enzyme. The substrate is shvj49/6acs o vtown in black and is bound to the acv/v6st o 9ajc4tive 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 enzymxe +mx9i)co/ue catalysed metabolic pathways shown below? Letters represent various products of individual reaction+ui)x9x /c moes.

  Which of the following describes the role of ;nh9 ug1skn1j .r:t lvw9l.w xinhibitors in enzyme-catalysed reactw1n .rlvlk x9g.u91j :s;whn tions?

  Which of the following corre:7wo is/4jnjyim k;(xctly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways sepi1 p4m/9+ c 6raiy(bjbuf7involving multiple steps and multiple enzymes. f 6p1r7/amjip b9ucs+yib( e 4

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 below? da)bv) sv t3 rdv*o02;ayc9qbrl;aj7

  Which of the following statements -dg93c 8+ uw+o mirnsv* rgj0sare true regarding regulation by end-product inhibitisg*wjr+ 9o0v c+3imsgnd-8ruon?
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 vi6-zg:x/k l ,.+fxx9noa xrmstructure of the lysozyme enzyme. The darkened structure zo.r -m:,agfn6xxx+ki vx9/ lin black is the substrate 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 study4a+ie+/ks2/ gl hoq af+6klr t,/ad su the effect of temperature on the activity of/+sqtuak a4, e 6l2l fdigr+ hk+a//so 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 how enzymes intez zp,x;y 2ozr ;xw7d6mract with substrates to catal x;,p ry;o7 zdwz2mxz6yze 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 cannbwc,y :3yeqz i1iq:+ be measured.

  How does denaturation change the properties o5c8q/5;v:rqh(kv ygq6abf;; l jt m odf an enzyme?

  Enzymes play a role in catalysing revv0var/. j;q00hru..uxhqv1 t;gjt yactions. Which of the following statements are true? r/tqgjv .00 1vq.xjavhrt;;y0. u h uv
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 from ectothermsc k+zia 6n e3z)g*vgts/9ci8l tha6*ia e )/gcg tnzkc38zvi+sl9 t have fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine con ph k-yt2x:fp93 4ocrzsists 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 2 9pyh opx:krfz-c34tpathway.
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 thelttq6p l2gg50 9igrkag ltm85y2:ui 4 rate of an enzymatic reaction. What is occurrink2gy mqgg ialr8 l9itlptg50:2 5ut46g during the phase labelled section X in the graph?

  An experiment tests the effecgu r8y1:i)m pft of changing substrate concentration on an enzymatic reaction. What could be the independent and dependen)rup m g8:yif1t variables in this experiment?

  The diagram shows the pathway t3x0u3d e9v jyj1aeoq+hat converts threonine to isoleucine.



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

  Enzyme A (Enz A) was2v;k rt3- uivx immobilized on a matrix and its activity was compared with that of a- ;i 3txv2kvur free enzyme in solution. The graph 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 s:d8c8gjw 2(c cra5jpw+ ,bc measily denatured. Which of the following is the best way to ke, cbpsj2cj5 wa8wcdrg c8+m:(ep enzymes active for a longer period of time?

  Which of the following describes some typ:qg i72t ngkc6es of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptyd3)2m rx)jj cides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a jd) 2 jr3)xmycconstant 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 substrsdaxm1duxjc / ).e;v,ate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the ,1 vu .m;jdd)/xesxcareaction, 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 a turnip o27 ds (r(tvnaroot 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 te7 (dnrtavo s2(st 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 nq 2;dhv s8 rv 2h(xtmf*tt(0aHMG- CoA reductase can lower ; txvtm(v0dtfa sqnh(r28h*2the 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 involo qh *wtk;5h6kved 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 gmi(p, (qv5q5y*9w hmvn;c9nzt1 a dyuiven an experiment which demonstrated the effec (19vv(h q5 ; wpu *dnmztimany9c,5qyt of temperature 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 ea.2jy +efp(x 5gney-gffect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate g ne-e y+gpaf5x(y2j.dependent variable for this experiment?

  A study has been conducted on the activity of a specific 9-+k1uqq yfg2 g td(pslactase (Bg10), analysik g9d2+ty-p qs1 qu(fgng the effect of 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 patientsser w0s jles)xm4ec 0dm,rs22- q0*lj with malaria. Describe how anti-malarial drugs are being discovered with new tec)2qj-exw0 0 es2smrjlc,ms4res0 d* l 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 tho6852sd a zfis;(mi gne concentration of an enzyme affects the rate of reaction s8g mnii 5;2sza(f6do.
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 react )/bqbs u(todbea0e1. ions. Which type(s) of metabolic reactions are condensatio.0 / teb)bu1( eodqsban reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of eno e,*smg8-r/c5 fkqz vzyme catalyzed reactions can be measuregfc oz rm,kvq/8* -s5ed.
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 intrt; m.ol mlmxwd62qd. w(mh)3pacellular and extracellular chemical reactions, given one exq;(tml.hwdmd63m2o lp ).m xwample 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.