Which of the following maqpyg6 ;y;z9 ilp+b o bw8xwlv2*(tx6ucromolecules describe a typical enzyme?

  What type of reaction i9 6sip,g -iqbbvm,23*; ms p2p ykihuas photosynthesis?

  What is the substrate for thmaq9bz q+kf q4v7s ,3ce enzyme lactase?

  Which of the following stages of cellula3e b xry 5pm: ioiv2i*2/sj,jdr respiration takes place in the cytoplasmise,yvjbm i op35j2/dxr i2:*?

  Which of the following would not be useyc p3)9n rqve5ful in determining the rate of an enzyme-catalyzed reace3 y n)r9v5qcption?

  Which of the following processes mayn89 yw+kw2 wcdmzcq1: be described as catabolism?

  Which of the following statements is best depictedg jb8;q 58.ju w;swhiq by the figure below?

  Which statement about enzyei-m-f , qqd8gmes is not true?

  Which of the following grap1fq- m(+dopq0zuuzpz7b; z p.hs best illustrates the relationship between temperature and the activity of enzymes such as lizb ;o-duzpfp(qzq 7z p.+m01upase?

1.Sketch a graph to show how increasing concentrations of substr) o e;sld(:dcl0 1jabeate affect enzyme ace;oal) d:0jl1 secdb(tivity.
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 diagra*xkth d fxf./0m outlining the Calviht.0kxdx f/*fn cycle is shown below.

The image below shows the catalytic site o k)lb iog)rkqnh) .8qc/amq18f an enzyme. The substrate is shown in black and is bound to the active 1o.gb aqm/hrc8))nqkq)8li ksite.





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 metabolc32xol +vd zu7ic pathways shown below? Letters represent various pcdz+2l7o3 vx uroducts of individual reactions.

  Which of the following describes the roiybds w5 5j+53nzd; uole of inhibitors in enzyme-catalysed reactio5byizdwd3js5 ; +5nu ons?

  Which of the following correctly describes photosynthesis or reh+;m). a bx80fredec fcgyx+6spiration?

Many enzymatic reactions happen as pathways involving .m 3dzpb0j:9 3hp6ldtkxlw g )sd4e/ rmultiple steps and multiple enzymes.3td p.e0bdwzx s/)49d g mlpjhrk :3l6

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

  Which of the following best describes x+2iahcj qtp-k,:yg(hh f -s )the inhibitor in the image below?

  Which of the following statements are true regarding regulat gh hh 0-kav.rttmi x3+xm391vion by end-product im i30kt xtha+13mhgx h9 v-r.vnhibition?
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 showxs zj -0 0ur 7.rpap4oi;tdi4es the structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the active site.dzs0terp j4x7 urpio.a;i40 -

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

The equipment below can be used to study the effec tw 9r :sph+/ka 8hq-evjtt+4ft of temperature on the activity of the enzym8 ts +phfq wat/er9jv+: 4-khte 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 w)kppg: u( (zrwith substrates to catalyup z(()pgkw:r ze 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 reactionsp-uzb (hkd ,lq 6kc,bb2(in(q can be measured.

  How does denaturation change thedk7jpo )uep)uor8is;( qw /v : properties of an enzyme?

  Enzymes play a role in catan5uvj .fdos) :lysing reactions. Which of the following statements are t: )sfun.j5ovd 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 fr:izz :75 hkfgm:z hoa0om ectotherms that have fluctuating body temperatz:0h z o:g af:mhz7i5kures?

  A metabolic pathway that converts threonine to the end-product isoleuc5o(o5wei awu*p 8q2:r8dv :c)umtpaoine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the las8)5c*5(euiwu m:d2op owava8rt p :oq t 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 tbi3oz, z4a)w m ik5tb8if)rg/he rate of an enzymatic reaction. What is occurring during the phi/ iak5 3fobg84irb),mzz t )wase labelled section X in the graph?

  An experiment tests theqlysk,s,ynxz 12l2.z effect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this experimentxy,q z1 k2zsn,yl.2ls?

  The diagram shows the pathway that c*bg; 6-mag x( (ynxajconverts 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 was compaz.1lw cs4doqhy(8bm . red with that of a free bs.1(d8 z 4cym.qlho wenzyme 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 easily denatured. Which of the following is gh5o+)*sei 62f3b7qgxxb wnw the best way to keepg5* xgq+w o2b3swb 6fnix)he7 enzymes active for a longer period of time?

  Which of the following describ 8m)5jby /-yyokzu q0ves some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptx.b v7p j w380flpv/xoides in the stomach. A study was carried oul/vx .pwoxv3p8j7f0 bt 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 enzyme with increasinkmb,wo: 48v n1 +ry6b, ebhkzsg substrate concentration. Similar concez khkv ,1:,4rneb8+bbm wo6y sntrations 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 stude7q mj,oej-w;h nt cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender 7omqw;,h j-ejto 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 z9h wv5grb. 9oenzyme HMG- CoA reductase can lower the pob 9gz9 5rh.wvroduction 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 in de 0c8ofhf0c 5mt2hv /ee5g6 fhonaturation?
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 reactionv :u tmi7f9/ *)nmewijs in the classroom and were given an experiment which demonstrated the effect of temperate v wnf)i:mj 9/*utmi7ure 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 incre*pzw6rg it2 :hobz4 2uasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent varia* gizo2:z6tbwurp2 4h ble for this experiment?

  A study has been conducted on the activity of a specifiqw,oo805tchzl,w qfr2plh : pzw9; 6ac lactase (Bg10), analysing the effect ofz 28 cqfq;w:htwl hrl0p,ao,95pz wo6 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 with7 m x*k-q, tgujzxa-ne66zc x( malaria. Describct 7q,z66 (jex*-xukagzxm- ne 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 of p+n 48 cptup.lan enzyme affects the rate of reaction4pp ctnl .pu8+.
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 dow.y:/h gl0p xlon or synthesized through metabolic reactions. Which type(s) o0lohx:.y/ gp lf metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate + zkuss2pmr59 of enzyme catalyzed reactions can be measured. mzu9skp5 2sr+
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 chk c18ygao57qc emical reactions, given one example o agqc7 oyc581kf 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.