Which of the following macromolecules describe a typical enzyme?07nh itn sne l2sz5;3l

  What type of reaction is phubc+ei6.hw 321 mjvykotosynthesis?

  What is the substrate fov1fq ib3s -fk2r the enzyme lactase?

  Which of the following stages of cellular r8 ;x6,scn 1usb:fwratl(aw9despiration takes place in the cytoplatwn u1:6dxf(a, rsc;al s w98bsm?

  Which of the following would not be useful in determining thequ7y:y/;md g8mmd + pj rate of an enzyme-ca:yd ;dgj/um 8m7mqp+ytalyzed reaction?

  Which of the following processes may bej41 dm;.cdmva described as catabolism?

  Which of the following statements is best depicted by the)y/b.c +ettyk figure below?

  Which statement about enzymes is not trbq*o-umzk9y nz 1x79vue?

  Which of the following graphs best illustrates the rlpb 4a26k lmb;elationship between temperature and the activity of enzymes such as li;b2 kb4 lmp6lapase?

1.Sketch a graph to show how increasing concentrationv:vblo/k :kv0-wjw 4 b x61+1rwacfvts of substrate affect enzyme activitvcv6:f0x/arkj +1 : ovv ktwwlb 1-4wby.
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 diagramiva9 8gmvmnkr1:y393v bm)pt outlining the Calvin cycln:89pv v93)ma1ykmtbgvr i3m e is shown below.

The image below shows the catalytic site ok0 k9tbfh4(s9 mtlwj)f an enzyme. The substrate is shown in black and is bound to the active sit9th9 wtkkjbsm)0(fl4 e.





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 path/qb8h u t*3ovjways shown below? vht j8o3*/ buqLetters represent various products of individual reactions.

  Which of the following describes the role of )cego6g97oc zi m 8gln5u.t9mm;n sh *inhibitors in enzyme-catalysed reactionos eu8)mio;l9c7 *gng nmztg95.6mhc s?

  Which of the following correctly wq*b,wn)(+)a9guydgi4 (c xzfp gt9jdescribes photosynthesis or respiration?

Many enzymatic reaction 0.6qfuec /kz9*v ecnvgirj :)s happen as pathways involving multiple steps and multiple enzymes. gz0u cicqe9vefk/ n6 j.:rv) *

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

  Which of the following best describes the inhifj6(tkrr:(zr cl k3e7bitor in the image below?

  Which of the following statenu ijw o4rt574ments are true regarding regulation by end-product inhibitioj45w i nou4rt7n?
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 structur/jt+u d5ljn di4u( 9vze of the lysozyme enzyme. The darkened struc5dj n +vziu9lt4ud/ j(ture 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 ey6ioisk /h)hke8*1d be used to study the effect of temperature on the activik/k6h oy h)8e iis*1dety 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 statements describes how enzymes intem;ie,qc4kz wm 7;zx4c ract with substrates tmi4ec z x4z7w,km;;qc o catalyze 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 reactiaznm olbz,.( 1zad-99qf*icsons can be measured.

  How does denaturation change th6bu-jda mlay+fzcnx mw98:3r0 x c64 ke properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following 167)fqohatuef9 ql8 gstatements are thl1o 7f)ftaqqu689 ge 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 fml.pp. bm6kh 0rom ectotherms that have fluctuating body t .kmm pblph60.emperatures?

  A metabolic pathway that converts 7avgv lref1/fb0ytz vi r)23:threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes beforeigebv3r fva01tv /fy 7rl:z2) 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:p xpoi+/v/vlppm x,g:c8 b4x 5z 7rbkc +v;to of an enzymatic reaction. What is occurring during the phase labelled section X in thtz;, +c/4b vxvxivbopl8 m +g5p: pxp/7k:croe graph?

  An experiment tests the effect of changing substrate concentration on atzv5yd; -ia4dn enzymatic reaction. What could be the independent and dependent variabldd5y4i ; zv-ates in this experiment?

  The diagram shows the 2* zul sz3kyc: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 was cf4k k+eyewcogc9 ;8cu +,0g hgompared with that of a free enzyme in solution. The graph shows thwuyfec08 ghk g c+9e+,4;g coke 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 id7ant3-x+f2ge;do ; e9vy 2dl ,w qcrdenatured. Which of the following is the best way to keep enzymes active for a long- 32r+oe e vd,ltg; 7;fdn2ycidaq w9xer period of time?

  Which of the following :;ly u;( lgjgjd+coz2me -qtsl3m03hdescribes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomachtidu2d) 2kp2c . A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperaturetd2kuc )2d 2ip 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 rj7*q2 sy3t3- opuaj qqate of reaction of an enzyme with 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 cur37ytuoapj-j 3q * q2sqve 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 turnip root into seci84: hcevt) -:cbh m5k.btkmall cubes. They measured approximately 5 g in a weighing dish, added 5b k 8cctm : evh-)h.ike:ctb450 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 enzyme HMG- CoA reducta hhr g;tq89slzwt1wdu92m b/ 6l2zm-jse can lower the lh2m9wj8rl wz2 1-gb/ztuq dt6s;m9hproduction 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 axnxqb(x)pr :* re 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 meb /x96ws6geivtabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperatuvgws b66x9/ iere 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 e t(fxc qgud*,f*z; mf d9faju5o)w0)37a ke amfficiency of lactx)w qkf3 u mcafg5ufjdza* (mdo7e*,ft0a9) ;ase activity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10)yoc: nv5fr36ut 5r7yxl- 5nkpg d(ln., analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to yndyln35: p5gkx-65uvr 7.c(nfrlto 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 oymap4+ s3 4j 839mmsgz; /)q zazeotdtreating patients with malaria. Describe how anti-malarial druasmmz94d8;moye so3za)p g/ zj3q4 +tgs 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 affect2yh zu(7( yfqkqv*s27udr+vm s the rate of reacq + v*(f(yk7 uurhmq22vdz7ystion.
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 ij9 lm)(x2gjqu5rt p w,b5x5zdown or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation95z wu 5b,2q5j(jtrx) mx gilp reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different war t-4* j5-,ge;r qc2xpsupfa hys the rate of enzyme catalyzed reactions can be measupe25fhs-ca,-p u*;gqrtx 4 jr red.
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 chemic y h 27ws3d;3tanjt,nzd0a1g wal reactions, given one exn,0dz3j wa2s31 7htdw ta;gnyample 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.