Which of the following ma /us*(.)uuic tbk90 c0ehrqutcromolecules describe a typical enzyme?

  What type of reaction is omeqaa8 imf;99r/s cfg 160by photosynthesis?

  What is the substrate for tfbvilkmvkm a.(+-b r63ucw0( he enzyme lactase?

  Which of the following stages of cellular respiration takes place in t)jv4km4qstlj tyw u ,)z ;8hz2he cytoplasm?jz) ,tl s8h2zutwk j);4 4vmqy

  Which of the following woul 2e:ooh6h 6mtbd not be useful in determining the rate of an enzyme-catalyzed reacti266: bomho tehon?

  Which of the followi-- qm-bhf9cdlng processes may be described as catabolism?

  Which of the following statements is best g,1o itten,vn3xi-0r3 9f tzj depicted by the figure below?

  Which statement about eno yp(3ozi88hy zymes is not true?

  Which of the following graphs best illustrates the relationeqgp8k8ftxqb+/ /wcjy *(nn- ship between temperature and the activity of enzymes s y-q/8bn*q+ e/ j(nwtpkgfx 8cuch as lipase?

1.Sketch a graph to show hrof/x9b5p y+.du ot.u+h9zzq ow increasing concentrations of substrate affect enzyme activityzho fb 9o.x/uqtdur5 9pz +.+y.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme w04g b6vxcjvmczqc ki) 6.3k6( sbqg-catalysed reactions. A diagram outlining the Calvi30jqi-vvc 6.kwcsq mgb4k(g 6bc)x z 6n cycle is shown below.

The image below shows the catalytic sitvqje f*d 3b,xh3r+0vh e of an enzyme. The substrate is shown in black and iseh0,jh qvr+x 3f* dbv3 bound 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 pathways shownwr*.smal8sn04 w6p pxr64bj v below? Letters reprl6sr8.rv0w*xbm4js pw6anp 4esent various products of individual reactions.

  Which of the following describes the role of inh3 a y 3y1vi3e+mr bwdgh0oke--ibitors in enzyme-catalysed reaction+k -0iy3bd e-m3rao3ew 1yv ghs?

  Which of the following correctly describes photos33w +cy-uh)oiusw 3hcynthesis or respiration?

Many enzymatic reactions happen as pathways in67e ina9bezi 7volving multiple steps and multiple enzymen79iaib 6 eze7s.

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

  Which of the following best deb)h8 t xu3z,knx 2laj8scribes the inhibitor in the image below?

  Which of the following s0my:y41mimh ftatements are true regarding regulation by end-product inhibition1 fiym hm0my:4?
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 eh28 f3 xo 5re75mn3wys6 xbzuho.u 3funzyme. The darkened structure in black is the substrate and b5 yuzx3nh. uf5 8sw6moxe33 u72rohfis 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 aeq 75: jqf5.i.n 2 8s3,qo ccawiympgsctivity of the enzy m c 3e5.syqigwqs f2:nac,ojp.87i5qme 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 inteu9y n).wq rr4tract with substrates to catalyze reactioy) 4tqu.rnr w9ns?
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 me1jtr-w gqc+b: asured.

  How does denaturatiou0 6u26+k)i 3u)y mka( nyzvtthym:hhn change the properties of an enzyme?

  Enzymes play a role in catalysing reactio+rsq ;vof):cy ns. Which of the following statements arycq:+ ;) rovsfe 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 separatese2mt fwdk6)q 6 mammals or endotherms from ectotherms that have fluctuate 6mft6qkdw 2)ing body temperatures?

  A metabolic pathway that converts threonine to the end-p sig(pr ry+mm,i 8qjx2py x:*(yy7.duroduct isoleucine consists of five reactions. Threonine is converted to vair xu*grd :+, p(yyj2qm.mipsy(7y8xrious intermediate 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 rat9qf u(99+g9ave nm mule of an enzymatic reaction. What is occurring during the+vu99 (qal9nmg9meuf phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentrati95lc0u /kslwp on on an enzymatic reaction. What could be the independent and dependent variables in this experipc9k0/ls5 wu lment?

  The diagram shows the lqkh*irbs: ml :5gs v+rf2). rol)lo.pathway that converts threonine 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 wysp +m) 2d6ngf4xz5eodf6 ,reas compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-axise,mn 4fs+6x2 d)eo5 6zypfgrd).



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.h-amby/d +ei umzvhu0:5 :mt4 Which of the following is the best way to keep e v: 4y+ b:hauh-0umt izmdem/5nzymes active for a longer period of time?

  Which of the following describes some td h1ld-7s zse1wkp +l-ypes of extracellular enzymes?

  The enzyme pepsin hydrorirup m1: n,i*lyses proteins to release peptides in the stomach. A study was carried out to determine the effect ori rnump 1*:i,f 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 rasjrb ci/ (k/f 72otno4te of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were ad/(j4 7b ncfskiort/o2ded 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 enx) w: 01temv du4ebz-3iz4oyizyme 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 to homogenize the tuou) zz:01xiedy-t 4i w43mbevrnip 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 sho4vf ak bgpp2qt0 c;6f*wn below. Inhibitors to the enzyme HMG- CoA reductase can lower 4f0;gp 6*acf2kvqb tp 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 i 1ahzn2(u-o) w orejf*n 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 weqagw y7v 9qf0a/1kk-x .e, dohre given an experiment which demonstrated the effect of1v -xdwk0g f hy ,k.7oa9aqe/q 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 effect of increasing temperature on the efficiency of lal1m odtbj) dlwlvz0)h5 -*-y ectase wdoz0- ey5vl*tl)d-)l mb1j hactivity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on th kt wjh4 xd2.qwu5-t/gwv+o7 ae activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase ttt.kj4 a ww+u x-h gdv5qw27o/o 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 wit -04uc 1rvfm ; dan. 1pib0vcqa4xt9sjh malariiab0n; tdur vqacvs14p1xc m9f0 .4 -ja. Describe 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 concentration ofrro( 8sbt 94ed6wp-t/h3kg vw6wm*r t an enzyme affects the rate of reaction. bptgrww6r ts/v*4(9wo6et3 m8d h- kr
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 orok 33 s++cfil:mv g)eqe;o,i h synthesized through metabolic reactions. Which type(s) of metabolic reactions are condenmefq+l,hek)o; 33ivc oi+g s :sation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differl: ) tufv0git2ent ways the rate of enzyme catalyzed reactions can be measured. tvitf0ug: )2l
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 reactr3zy:,mi-emc ions, given one example of each type of react,ze3y:c rm -miion.
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.