Which of the following maeosao *g;.*kwvdl;b,md a 0 r8cromolecules describe a typical enzyme?

  What type of reaction ikjxp 3zh )*jzx -w6.l/ bb7ufos photosynthesis?

  What is the substrate foro -s-n gp(53i;dvzjjz the enzyme lactase?

  Which of the following stages of c5bb kdjidv1/2 ellular respiration takes place in the cytoplasbb2k /dvd1i5jm?

  Which of the following would not be useful in determinidm)9nvd79 1l 3sn( :so8 exv hzb6mnkjng the rate of an enzyme-catalyzed reaction? 9dvs39 b:nkd(n7lmezsmv 8o1nx6jh)

  Which of the following processes may be describe33yk b88s. qsoa l0cxsa3he ,vd as catabolism?

  Which of the followinttk;9d822 z)fl/uri0dq t h0adtaiq,g statements is best depicted by the figure below?

  Which statement about enzyz:r9a t+y* i1w wzgn5pmes is not true?

  Which of the following graphs best illustrates the relatio8xt41g d 7o.1wij t8zmb: d9wao :rbhnnship between temperature and the activity of enzymgbh1jb8io 8:da9d nt4x7rtm 1.zw o :wes such as lipase?

1.Sketch a graph to sh2 ok402 fhe)0/vyd tmlae3jueow how increasing concentrations of substrate affect enzyme actea 3hk /022leeo0d)j4ftym uvivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysedb6t , vlyazuhsl*2mrq7 .s,;d reactions. A diagram outlining the Calvin cycle ist b7 z,6qsa,m.l;2uvlyds *rh shown below.

The image below shows the catalytic site of an enzyme. T1p*keh+ gb;dt he substrate is shown in black and i+bke* h;td g1ps 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 enzym*t )gcax7whl u q h2n5+5oesq4e catalysed metabolic pathways shown below? Letters represent various products of ia5hgtx+w q47*ol25c nshq) uendividual reactions.

  Which of the followi8foz . wwo+ i9uo8c,mtng describes the role of inhibitors in enzyme-catalysed reactiocf9wo zo.om 8+w,8i utns?

  Which of the following co ( b(tlp8by) xnp9pj3prrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways iybx2 6t34e gymnvolving multiple steps and multiple enzymes. te3 26gm byxy4

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

  Which of the following best describes the inhibitor in thz7b2q p1z /d9g nn9zcle image below?

  Which of the following statements are trun)z / ny ;7v.eu6c;c5qxcysdk e regarding regulation by end-product inhiucy);z.cenyn5k vx76q;c/sd bition?
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 structurkzac -n,ir(/le4-i uwmpy hgmx- ;w ;)e of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the actg ea-nmk-u cizl rw )xmiwy4/h-(;,p;ive site.

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

The equipment below can be used 6bsf..xyuw/z 6h wwonmb :6;ato study the effect of temperature on the activity of the enzy :ua6z hfxwby no.;s6bwmw./6me 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 howa,*sjqga/r6pz: jj0 a4a ubt1 enzymes interact with substrates to catalyze reactiobzr /p0jat 4gaaj :*,asu j16qns?
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 measure5.7y h aq-scxv -+xbb6bzdr-z d.

  How does denaturation change the properties of an enzyme?i-cov f7/ts1y6h ks j0

  Enzymes play a role in caxxri2/ oszm7bg:fg+ ,talysing reactions. Which of the following statements are tr z7rfi/g,s+2omxg : xbue?
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 endk7w: dj m3tdaw,tqxof::r4vwmi 9 9,k otherms from ectotherms that have fluctd7 tt:d4:w i3,j vm xaqrf:, kow99kmwuating body temperatures?

  A metabolic pathway that convervh ,p.y7bi s(bts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intey (sv.i,hp7 bbrmediate 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 rate of an enzymatic reacti 5yqn d,fp08trk)m;9qz : cqkcon. What is occurring during the phase labelled section X in thec,8 q5m dkq90f:pz; rtyknq c) graph?

  An experiment tests * 2ose0 f nxzjr5,g ;ptj0bvi)the effect of changing substrate concentration on an enzymatic reaction. What could be the independent and depende;fb *gp sre)0x jzt520onj,v int variables in this experiment?

  The diagram shows the pathway that converts thre, x,af7c5 bmy 0btfma3onine to isoleucine.



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

  Enzyme A (Enz A) was immobiliz*k3cwo*-f,ol( ts;njx.ako .,it pv led on a matrix and its activity was compared with that of a freev*x.w(,.* t;klop naso fiklj to-c3, 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 easily denatured. Which of thef*w,/ )+ny viqvhuf;f following is the best way to keep enzymes active for a longer+uvq vf,h)ffiwn ;* y/ period of time?

  Which of the following describes sipnac;1jn w7,9 f 29 6oizpc4iuuzg c3ome types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in theutfkkd (1wwax v,pdx7 -5d 8wzt9zz-1 stomach. A study was carried out tod 11 ww ,dpt8(7ax fuzvkx9zkd t-5-wz 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 increasing subs,pmbv9 ej a:u-trate com e u:,a9b-vpjncentration. Similar concentrations 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 student cut a tuvs () sbl,5x ,s;v) j8vspcx;aep2zj jrnip root into small cubes. They measured approximately 5 g in a weighing dish, addev)pj,cbs;,sx2a j5; (lxj8zsev) p sv d 50 ml water and used a blender to 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 enzym:q:im*ksaq -pe HMG- CoA reductase can lower the production of choik* am:q:q p-slesterol.


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 followinblp7 bpw; 3ti1-h 1hhmg are involved 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 reactioh: h2jf*;qnw wftyfxzk(1. p7ns in the classroom and were given an experiment which demonstrated the effecqkh* n .1j7hyzx( ffpfww:2;t t 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 effecjs w5ls oz9lc 81k+h8em9os 3rt of increasing temperature on the efficiency of lactas szk5l lc+s8o98mwje3h1so9 re activity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactaset p 9q gk h70d0kgc;-lq;ysf8a (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as gpskga 0y0ktqd hf79;cq;8- l 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 with m/z/gcri.,j 4n khm9 daalaria. Describe how anti-malarial drugs are being discovered with new t9hrj.izn/,d ka4m/g c echnologies.
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 concentratie4 6sztb ,x2lpttw).u d j*4exon of an enzyme affects the rate of reaction. ju d24*steextwb ).zx,p4l6 t
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 synthesizedqqlvo 9 9 fttva/81mr( through metabolic reactions. Which type(s) of mot qafr/ (l9mvtv891qetabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed r *bw c2 a,dfgqe/pkz2s0;r:a ieactions can be measuc2p eg zaaqfks*b,iw;02d: /rred.
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 extr9b r0jqtko17racellular chemical reactions, given t 7qjrr9ko 0b1one example 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.