Which of the following macromoif7:ga y(c rsey;:r1dlecules describe a typical enzyme?

  What type of reactionpx po yh4ri* 1vi1v8b- is photosynthesis?

  What is the substrate for the enzyme lactasdhdxo. pa(x 6)a7 lmj0g48afve?

  Which of the followinb89a-bcp hwo w)4a 5)vmme5sa g stages of cellular respiration takes place in the cytoplasm? ahb w5e)v a45p 9caso) b8mmw-

  Which of the following wouvq47 k+vu fhe 3m*ew*fm8(i0qh60 p dxzmcbb*ld not be useful in determining the rate of an enzyme- efhp*3xkmqmzh0 fvq6m*4v87+(0dicewb*ub catalyzed reaction?

  Which of the following processes may be described as catabolism?sm 5oqcnwyva ( 36(tlm*5pjo.yr( aewf 05m9x

  Which of the following statements is best depicted by the figurer- psbo0ood+lb, g14r below?

  Which statement about enzymes isp2lcgr 407(w f aabek3 not true?

  Which of the following graphs best illustrates theoz2-t zdq * 1-xj/udfb relationship between temperature and the activity of enzymes such as liz oxb-u q2ftd-/1zd*j pase?

1.Sketch a graph to show how increasing concentratiyg(a,7rni d,w6.pe y w8q*abt ons of substrate affect enzyme act gitw 6y. y,d7r(*e8a wqpbna,ivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalyseg8qu+4lha 1v c/(qhp cd reactions. A diagram outlining the h1l qc(q8av+p /gh4ucCalvin cycle is shown below.

The image below shows the catalytic site of an e*l/q t1gp;u4jqn5jezyuynzv ku /y:q80+ 0gznzyme. The substrate is shown in black andu0qq185 vt q/l4kzj; ugyzyp *:g+jynn z/ 0ue 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 deschobt,l80 pq;qyk -b(vriptions of the enzyme catalysed metabolic pathways shown below? Letters representqkpbqoly08tv hb ;,-( various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed-ppb ; y .a3;tc3ujbvl reactb3lat bcjp;p v.y-;u3ions?

  Which of the following correctly describes photosynthesis or respiral )6asjpyp; 6ation?

Many enzymatic reactions happen as pathways involving multiple steps andib9;c+ qsxd xm3 obpw7g 0rg.9) zeke- multiple enzy pz9m9csb7qgx 3 ekidbw0xro.-e;g +) mes.

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

  Which of the following best describj,;hi6dwyap0(l ls2v+b o1 r ges the inhibitor in the image below?

  Which of the following a 23rwu.ytqvnp 4-vb pxod9;q(*ihc9statements are true regarding regulation by end-product inhibitio92r;uacdw 9p3ivqn hp qt y*.(4 bvox-n?
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 enzyme. The dh: ct7a ywfhqpb7ow4-f /:6rtarkened structur:f7tp 4q: w/ wyfhr-h7t6aobc e in black is 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 study the effect of temperature on the activi9s;q,c rk(6hnqo 7 cbztcc9rs7h,z(qnq;o 6 kby of the enzyme 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 statelp; rrhjv3:- gments describes how enzymes interact with substrates to catalyze rear:vgrjph- ; l3ctions?
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 reactn2b-5zg+ t x 6;ijyncoions can be measured.

  How does denaturation change the propertid; dmqd/j;1n36 ck usjes of an enzyme?

  Enzymes play a role in catalysing reactdik/d otmdh r0v6d ha5f-87.j ions. Which of the following statements are tr6 8h5ai/rdd f.7kvhm j dt0do-ue?
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 endothermsr:5 t k54nug/qwr4gir from ectotherms that have fluctuating bodw/:5 45 4ikrrgungtqry temperatures?

  A metabolic pathway thatg e a1(rg*1tqf converts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate product(1fte1r a *gqgs 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 enzymatipp2( kl f;r1xwd *uollf,o/6 cc reaction. What is occurring durf k,1lo*(r polwfpcx6;/ld2uing the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate conce7 pqj bjc hjx8b83.3i.x u0tzzpkm;b 9r f8.bhntration on an enzymatic reaction. Whatfp z t3 8;qi937 .bx zjxk.jp0bh8c.8rbuhbjm could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that convznz+b u3h. l4jnwd+ntqg2y*/jc y 3;di4mg /berts 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 actvyxg,o 3 1)xtsfcm+ d*ivity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axy +xtg3xvfso* 1,d m)cis) 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 k:5el5f2 xrdx easily denatured. Which of the following is the best way to keep enzymes active for a longer : fdkx xe2l55rperiod of time?

  Which of the following describes some types of extracellular enzymb1j1s1m -ezuq cpw.j :es?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stur2-djq.ei 8k rdy was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant tem .r q2ek8jid-rperature 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 withkrls9i/iu0x(h39l j g increasing substrate concentration. 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 il0kx93uijh9 r/gs( l enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a stuj -kci;wxm n)-dent 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 homogenizx) njc;mw-k -ie 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 tvf5 bu2fyt 7qfenz881,k6f nis shown below. Inhibitors to the enzyme HMG- CoA reductase can lower 56t fzn f8kbyeu q,2t1fn78vfthe 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 e4s qbu.mbl m-.b+nf,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 reactions in the c pq7gls7l q; bzn55q1xlassroom and were given an egp5zq7q qxs1l 5l;7nbxperiment which demonstrated the effect 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 effect of increasing temperature on the efficiency of p nl:o ,ca11bhar;9iw lactase activity is tested. Which is an appropriate dependent variablwn h:c ;9,r pi1aabo1le for this experiment?

  A study has been conducted on the activity of a specific lbf7,m:la1 ;rf4f6p00p stu ggq( prn factase (Bg10), analysing the effect of pH, temperature and glucose concentrationg,6apgffpfmt:( 1l7q rnu ; 0rf psb04, 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 pati7.tgx ig)n o; skkin4 ;8n:iawents with malaria. De .gx io;i8nti:;7gkw4 )nknsascribe 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 an enzyme affects the rax 5binu h,n)g)te of reac)ngbuh,i )n 5xtion.
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 reah8y*,zj xp04y ms ynk3ctions. Which type(s) of metabolic reactions 8yxhns4y, y jzk3mp*0are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzym:e/sa1flrlm6g kw661c jfvf4 e catalyzed reactions can be measuredmf6cl6 6l1/fgejwks va 41: fr.
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 reactions, pd,(v(g2ywp 1vhv5dc q (v:iku/eh w 6given one ex ivp h/y6pe(v (vwkg2hd w5 u,vc(q:d1ample 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.