Which of the following macromoleculed9 rzbur im/7 )t*gob/s describe a typical enzyme?

  What type of reaction is photosyng:4j9z ioxww( thesis?

  What is the substrate for the enzy6 ci fltd 40bjbt6q964jx.oqeme lactase?

  Which of the following stages of cellular respiration takes place in the ci):zs,sezq(fdo6 - k iytopla,df)k6zs( -iz e:isq osm?

  Which of the following would not be useful in determining the rate of an enzymut k io35m )su():crb c9l-wgfe-cams tocik5r:bf c)gl-3u( uw9)talyzed reaction?

  Which of the following processes may be d1ju:6e1wtxh nh0hoh 1escribed as catabolism?

  Which of the following statements is best depicteibf/s. qn ,7lod by the figure below?

  Which statement about enzymes is nonwe x uk6q36hz 8jegsm1e:l 63t true?

  Which of the following graphs best illustrates zq/xr 26mlz/mw8 q(vt the relationship between temperature and the activity mr2tql8vw(/qxzm/z 6 of enzymes such as lipase?

1.Sketch a graph to show how incrvat .,-+i m lgxyi8t)beasing concentrations of substrate affect enzym8gi tv,).+- yi tablmxe activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series oidw2bunxe 6zra:0onnzsd5, ;6b4 er 8f enzyme catalysed reactions. A diagram outlining the Calvin cycledei4z0e nd5auoxwr6; bbz2n :n,s68 r is shown below.

The image below shows the ,pugt;(8/f ,bs akny5 2xckrlcatalytic site of an enzyme. The substrate is shown in blas2 k ,8lnc,y(fx/u;5rbtgp kack and is 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 rpb 6ec)-r(h+ enh w.x7haw6ucatalysed metabolic pathways shown below? Letters represent various products of indp(+nbaw- ch.rwhue6r h)x76 e ividual reactions.

  Which of the following describes the role of iin 8pscv:ye;3 )ei)uuu1x n e:nhibitors in enzyme-catalysed react:ec) v:yne sn3 u8;)ieupxui1ions?

  Which of the following correctly describes photosynthesis or96h we cs/p3yzs:.gjf.1k f(ltjkjmdl; ) k3 t respiration?

Many enzymatic reactions r.zcu ,*bqovhjy753 vhappen as pathways involving multiple steps and multiple enzymes. zb*.,37 qvr ujvyoc5h

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

  Which of the following best 9z5tcmotbi k4aze/8tu,r p-;describes the inhibitor in the image below?

  Which of the following statements voxb5 j;:h40abkt 3tn are true regarding regulation by end-product ibk:otbvx4nh0t 3;j5a nhibition?
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 .zd6/uk vvlmob4szzm-)-qv5*jqr sms * tl ..the lysozyme enzyme. The darkened structure in black iom*v tqr vvldm6q*j/4z z5.kz m.)-ss sb-lu. s 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 studqnrnrgv1 z 478y the effect of temperature on the activity of the enzyn7 rzr1g4 qn8vme 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 describ ftna0a6p8jrq3yt ,s8es how enzymes interact with substrates to catalyzen388 jts tya,f qrap60 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 re:t4q th )ek+w pbod7.v8v et:eactions can be measured.

  How does denaturation cvar;3 zw:( y-lld)p yxhange the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statementbdp-fp*jv+na c46 1ja s are tv6 *+1j fdjapb c-4apnrue?
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 endother d8zmgnmogb 68n /7v*sms from ectotherms that have f*mggm 7b8n6 sv dnz/8oluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine cons :9/hbs i 6cd-vcalro -oa0;beists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted t 6-badi:hoco ;9s -vl 0/eabrco 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 effdva8 v;tx tk di/210oyect of increasing pH on the rate of an enzymatic reaction.ik /tvoy0 avtd8d12; x What is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changingv 1ymk 8:fnn9w substrate concentration on an enzymatic reaction. What could be the independent and dependent variablnfnkw:m9 1y8v es in this experiment?

  The diagram shows the pathway that converts threonine ti4 z/7 ; 6)iqgtv vwo8lfkt6hbo isoleucine.



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

  Enzyme A (Enz A) was im +aqj;rf,cf0nmobilized on a matrix and its activity was compared with that of a free enzyme in solution. Thrj,c;fa n +q0fe 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 the best guq6:lqnobso6( 3tmvuhvp4 52:ua)y8u, y gi way to keep 5u2v6aq q )bv8mgo pit (,yo :u sh6lgu:43ynuenzymes active for a longer period of time?

  Which of the following describes some types of extracellular enzymewgrv twt557jba3o)i:vms0e /s?

  The enzyme pepsin hydrolyses proteins to r1-oos2rdlg-) dp l) fxh2/s kaelease peptides in the stomach. A study was carried out to determine the effect of increasing substrate concent a12r))d/ogs-skl2 -hpxdf l oration 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 e.6*)nvskimcuy+- zla nzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity wk)cn*iusz6.y+ -m va las 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,nrrn:cyvr, 8/8 fk9,* ojlyc q 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 turnip root. The homogenate was filtered and the liquid extrac9yv ryn*,f8q/l, r njrcko:8ct 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 v, mw0*6 zi7ynior/aqyh*i s:rn s 1w(to the enzyme HMG- CoA reductase can lower the prod(zhaqin *s: my/o7 s*y rvwiw, r60in1uction 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 :t67f;jpa:qef kib4 cnaturation?
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 classpo 5cer6hh l93(gjfm /room and were given an experiment which demonstrated the effect of temperature on a catabolic reac(r hm 6g3jc9le /fo5phtion.
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 temperaz7 ;h5xa t/fnbture on the efficiency of lactbaz x57nhft;/ase activity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activityv ovowv2dn:z;i+-* wd of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may - *vi+zodo;dnw :wvv2potentially 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 /syp:l) : 6oka-,b,mnmbe rkzfind new drugs for treating patients with malaria. Describe how anti-malarial drugs arram-k,skol p /m):e by6zb n:,e 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 vkqgw g-g*e 0q0 hbopex:+c3* of an enzyme affects the rate of reaction. w*v+ opb0hk g3qegx0* cqe:-g
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 re l kxthc2t/(/zactions. Which type(s) of metabolic reactions are condensation ctzx(h//k2 ltreactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzym x18.jg.csr nde catalyzed reactions can be measurjcxrs. g8.n1 ded.
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 cw 3:n0qwpedb3 hemical reactions, given one example of each type of reactqw 3d :pebn0w3ion.
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.