Which of the following macromolecules descreri8ombvt;0 6j;x m0i xsa /u5ibe a typical enzyme?

  What type of reaction i 3 djb .9.)vjpres0lwlwl* b+zpa/(zgs photosynthesis?

  What is the substrate for thevirdlcrym+n-(i(y: 7 ap( 0tbm7 4mqx enzyme lactase?

  Which of the following stages of cu fx(frv 5( ksx9quo3.ellular respiration takes place in the cytoplasm? u((3 9v5 sr uo.xqkfxf

  Which of the following would not be useful in determining;dqtz1ekz 3rlu9 (b+f the rate of an enzyme-catalyzed reactr zbt+;3(u1q9k zdl feion?

  Which of the followin s +haoqz4 7;rhecwmsy.; l(,ag processes may be described as catabolism?

  Which of the following statements is best depicted bbg+adn (s dio 0-z-4rwy the figure below?

  Which statement about enzymes isw hxy gg53z 45ldb5y;g not true?

  Which of the following graphs best illustrates the relatp6rh*ub k(-wj ionship between temperature and the activity of ebh p*6 (rwu-jknzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrat.6bncohc49tk e affect enzymeotb k 69hc4.nc activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of e8 rjui56k/)s ne hgwg 3-+58lfbdaz xpnzyme catalysed reactions. A diagram outlining the Calvin cyclez3ngi6ws8h+j-a)kr gpf le/58ubxd5 is shown below.

The image below shows the catalytic site of an enzyme. The substrate is 2n,shqa +;1- mcsc: o+dcmnvmshown in black and is bound toqo;s c c2v m+n m,h+1:dn-casm 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 pat gejbz1z4bm)+v7 8;ou cqyv;dhways shown below? Letters rmzd)c1oeu+b;vb y8jqv gz; 74epresent various products of individual reactions.

  Which of the followi in dm63.;v edq5a(gs0y4g *uq2jplzbng describes the role of inhibitors in enzyme-catalysed reactionspg.* n jdlq60dq; (v u3me4g5by2 zais?

  Which of the following cor 6bw dd18 fbj(gr;7amzrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving mul7/nxn/b 3 lhe1x b*.)qz+ vaxx(famw e)7fl vwtiple steps and multiple37. 7mlq*xln/ab 1z wax ))bhvfexnf/wvxe+( enzymes.

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

  Which of the following best describes the inhibni qrwh52q9mk5;u 46ffu)ii bitor in the image below?

  Which of the following statements are true regarding regulationi6 2ltq-/1flfz+t,r/uq* kl th xxxtk7x :,z g by end-product inhibiixzhg 6 2/ *tttx7lzxk,flq :-rl/q tu1,kf +xtion?
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 lysozymewk;q 8nhh;p)ozw lw ;, enzyme. The darkened structure in black is the substrate and is bound at the active wwpw hh8znl;,oq; ;k)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 act kn4 r3azutt19ivity of the enzz34t rut9k1n ayme 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 descn+03q(qj hj1rgmxk/z+6bcc eribes how enzymes interact with substrates to catalyze reactiz/qn ++g1 3 mhkxe jbrcj(c6q0ons?
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 caan; x,imilp;3j2e bv* ,ccn,ftalysed reactions can be measured.

  How does denaturation change the properties o1vp-1 q;.8 ,thfgybreyvsh0 wf an enzyme?

  Enzymes play a role 5xp1w/+(tkt 4t2xmlwtqu7 qbin catalysing reactions. Which of the following statements are true? xpl4w x b2muqt5w/7 kq(1+t tt
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 separaoas4 ohev-7 h,tes mammals or endotherms from ectotherms that have fluctuatingo h-ev,aos4h7 body temperatures?

  A metabolic pathway tqs +d+s(oyib .e u4l+uku:iw ,hat converts 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 enzyuk.ld sb,uyisq wu++ e+(io:4me 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 effectq 6jj alhv*5 k1fa59vu, km,yp of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the5j*,j5k a6mlkhqv,fp va y u91 graph?

  An experiment tests the effect of changing substrate concentration8zg/hp2- vfz91ytuo l on an enzymatic reac/lh 8f-29p gztzuvy o1tion. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucinotmmooo -s9-z9tn/t -bg l5 c4e.



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 wac(v8d(2dannrwwc y(ih2 ).8o1 u bjaps compared with that of a free enzyme in solution. The graph showry cn((duo8 8)dbc. 1pw22nwhv ja(ai s 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 thezjhyn/cf1 cv f1wh9 +mn (s0t0 following is the best way to keep enzymes active for a longer periodsc +(wthz90 ycv n11/fm h0fjn of time?

  Which of the following describes eht/5d;-6rq yqu.mf 5ez -b)jwf,y eqsome types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A 4 ds*qt (hg, f0 vfu*hhyt4c*astudy hcfh*gty*d4u0*4tvsha( q ,f was carried out to determine the effect of increasing substrate concentration 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 enzymju/cju : q*ciok6)ssw3 pg5c( e with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activsip*/ cg6u)j5( :3o cujqsck wity 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 r86l e3c,uq ikjoot 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 exq3 i,l6eu 8kjctract 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 re/sw*0w;x7wdp vt7lho ductase can lower the production of cholesterohv*w77lx /wt o;0pd wsl.


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 )wo d.s9x: *+xdpjhiedenaturation?
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 givenwh+wzh2 fdp/ 5 an experiment which demonstrated the effect of temperature on a catabolic reacti+wwh2f zhd5p/on.
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 on tbl r x;s1am3vybk9y js9x pvl2,0wl . b:l.f,the efficiency of lactase activity is tested. Which is an appropriate dependent ,v:b mwbr0lt 9s ljx. ykxspfl by;,213v.la9 variable for this experiment?

  A study has been con4h,0g9do iy en 8jwn+e:2ywps,g3py u ducted on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature anw+ ne9y: ipg,0d8,h jg34pweuny 2 soyd 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 patientslt3k qu4h+a g 0m/pz4s with malaria. Describe how anti-malarial drugs are being discovered wl04hsma +qp/k zu4t g3ith 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 increasingyz/ph );fb )ny the concentration of an enzyme affects the rate of reacy fb)p h/;)yzntion.
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 syntheb oo .x5, n12e+ wh/evcokv9lbsized through metabolic reactions. Which type(s) of metaboli5e e2c+.hvb bl oon19ow/kvx ,c reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate ot:4q*++qda yxosu(s n f enzyme catalyzed reactions can be measured. s*4 nqdts+y+a:o u(qx
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 el3tu( (x8vqox xtracellular chemical reactions, given one example of each type of reac 8x3tl(q vu(oxtion.
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.