Which of the following macromolecules descr,i 1gharmsp37ibe a typical enzyme?

  What type of reactioe /j7*gg ygo( g/qc/r;4rdapun is photosynthesis?

  What is the substrate fo t,dbxc:u,/bp r the enzyme lactase?

  Which of the following stages of cellular respjii ywupkhq3 l+r r2+y7gm(4h02-pajiration takes place in the cytoplasm? ah0 (32+yrjrjmhqy2-ipi lkp7g 4+uw

  Which of the following would not be useful in determi0 fgse11 ;snyh ;y)jnkning the rate of an enzyme-cata1j gy se;f0h1ynksn; )lyzed reaction?

  Which of the following processes may be described ayow aionw k+3n).8o6 as catabolism?

  Which of the following statements is best depicted by thyu/d l8y)gu/fv2vr wh8xc(y 0e figure below?

  Which statement about enzymes is not yhn *2yv1,oiotrue?

  Which of the following graphs best illustraa57kbw* wk os2nk4. bates the relationship between temperature and the activity of enzymes suchka2 w5*sbw 4k7. oabnk as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect e(q /xjl:n.p annzyme activity. nnqpaj(xl/: .
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a s-y9ba oo+y0mperies of enzyme catalysed reactions. A diagram outlining bay9 mp0+o -oythe Calvin cycle is shown below.

The image below shows.vrwwoqy3t : 7 the catalytic site of an enzyme. The substrate is shown in black and is bound to the act7:3twv .wor yqive 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 descriptionssr849ve hb7; ,rkcffl/ u liv2 of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individif/8;hl 2fvur4ec9bk l 7 sr,vual reactions.

  Which of the following describes the role of inhibitors in enzyfnq /7y3 )kg jn-z3hty.l/qo eme-catalysed reac ly/)nt-gfh3kjoenq y/.q73 ztions?

  Which of the following correctly describes photosynthesis or res ow 3n6aee6yosh2o57wkdy3)zpiration?

Many enzymatic reactions happen as paq1hltspmr0ej;wwe xn5i) u6,5z, ,yc thways involving multiple steps and multiple enzymes)qi x,5h,e jr06w5tms e,un ;lpyzcw1 .

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

  Which of the following best describes ti ts9o i u2t/nn1(dynej* api oi)0v/5he inhibitor in the image below?

  Which of the following st5 9xx(q q-o*gbso* ,hynjyu7 uf; nxc9atements are true regarding regulation by end-product inhibition?(*-*y7bcxnyj, ouqoh;sx5 ufxqgn99
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 darkejld: ;) uc7wusned structure in black;wclu )s 7:duj 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 act h*;dh+ywa2 nz2,3p(kxrkcijivity of the enzyme am i(2;y*n3wkdjc p ,xahhk 2+rzylase.



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 with substratee .mgk-bn0pd0- lbpju7-bq j:s t d7 bqg pb0lk pe0-:jnj-m.-ubo 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 reactions can be measuroxjdgg*3r2d 8 3qfr:xysru(.ed.

  How does denaturation changq5z.wn-vv 7hde the properties of an enzyme?

  Enzymes play a role in catalysingbaa)n. /alx6x hk f0tulsl;11 reactions. Which of the following statements are tua.1b t1fha)ka6lx n0; /llx srue?
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 ed9bolxd3 1 cb(ndotherms from ectotherms that have fluctuating bb d 3dlbc(x9o1ody temperatures?

  A metabolic pathway that converts threonine to 0l*78 jt4pjr6 ksachrthe end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme i0 7s46tjl*rch 8jpkarn 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 6ea3 p*uah x-ngrg(r.increasing pH on the rate of an enzymatic reaction6xgnega-* .r3 (auh rp. What is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration o t9m tsz jlit:*8( ch822asdnjn an enzymatic reaction. What could be the independent and dependent v(8nitssd22j:9jm8t h acl *ztariables in this experiment?

  The diagram shows the pathway that -;dh g9 cvuhl9converts 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 oj:nfntq0 ny ks3/+1a a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH s3otnnqj+0yfn /a1:k (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. Whig5 aqensyoy6/z) ,) lhch of the following is the best way to kee 6nlyye)s/z)go5hq,a p enzymes active for a longer period of time?

  Which of the followif+9jm pi e6wxox:e rqq4.(m o9ng describes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteinjcba0, u.w q bz7 dumo4(va6)ws to release peptides in the stomach. A study was carried out to determine the efqw bab vwa6)ud7o,zc( mj 4.u0fect 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 rcn: 4f l1hl/ordw88utate of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently ttd18 r uonl4cw8lh :f/o 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 turnip root into smal1qa vywo *4.l:w9lxzjl cubes. They measured approximat.9 ylwqol xz1j*a4 :wvely 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 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 re h.qro6z 8 (,bq8u dt*bqy:xzeductase can lower the production of chq8 ezqx.hb 8: utr,qdby*6( zoolesterol.


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 denaturatv8u/23fz xf-y/bijsi(aci 8k ion?
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 th- e :sdrmv)ku(cn4lzd6o 1xl-e classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reacti:clmv z1ln6 -dko(e)4rs -xdu on.
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 effe;rlj w ,pc q;v,me178kbxd v0uct of increasing temperature on the efficiency of lactase activity is tested. Which is qp,1u bdc;,mwk8v 0jrelx ;7van appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lad akiyz;,q 4kb3ymj8 )5jh,r rctase (Bg10), analysing the effect of pH, ij,ryh 5z8krbaqdy, m4k3 )j; 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 drug;:vbc 6 ne7x4xvihd7s s for treating patients with malaria. Describe how anti-malarial drugs av 4x6visx;en h7:7bdcre 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 t-v7s7 ewd5aaphe concentration of an enzyme affects the rate of reaction.swv daa7 5pe7-
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 synthesiza*l4.hyy8qsac c e q29ed through metabolic reactions. Which type(s) of metabolic .l c*28s aycyqe4h9qareactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differeslbt (- u3jw7mec +(msnt ways the rate of enzyme catalyzed reactions can be measu7bj(c - mselsu+ wmt3(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 a zj 9e3s46;wrwdbp :yeapuv;2k .5xbond extracellular chemical reactions, given one ed rbpe3 peu 4ba;sz5:k2ov 9x.jw ;wy6xample 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.