Which of the following macromolecules deyb;o 2r +lept6scribe a typical enzyme?

  What type of reactiocmk jn(f4o.s.n is photosynthesis?

  What is the substrate for the enzyme lq*tdyx7,fe 0oactase?

  Which of the following stages of cellular respiration takes place in the cytoplap , lcxcq*)etup/u)r 6)*pulepc/6rt) xq,c usm?

  Which of the following wfya3.)s1 s)ym cj;trj l ss+re 4gb60gould not be useful in determining the rate of an enzyme-catalyze+j1abcg)flems4ry . s rtysg36sj;0)d reaction?

  Which of the following processes may be desce:jxl0 ed-mtw0r *x,iribed as catabolism?

  Which of the following statements is bes7kkwki94yfpl* s 8b;ut depicted by the figure below?

  Which statement aboutmvgja*cuy2+)wuo-n; qf hm 03 enzymes is not true?

  Which of the following graphs best illustrates the relationship between tempex4u zd(bb,gwx (-;ns;gs m+fgratu(fnbxdz;gw4g xbs+ g m-,u;(sre and the activity of enzymes such as lipase?

1.Sketch a graph to shl ji(fig-u ;0tpv-9 taow how increasing concentrations of substrate affect enzyme tv0-( ;u9itjifaplg- activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catfs h-.v2elw ug 6,jfa4alysed reactions. A diagram outlining the Calvin f,leu. wj2ga-6fsvh 4cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is sho,b rwc1rn t16uu3 vu/awn in black and is bound to the nrtua1 /6uc wr3vu 1b,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 ef 7wj0ncg 6tn,t1 njz,:z s8rcnzyme catalysed metabolic pathways shown below? Letters represent various jtcctfszw, ng8,r0 7 j:61nzn products of individual reactions.

  Which of the following desm+aegs ti(0e)f pc1v sa00 +fvcribes the role of inhibitors in enzyme-catalysed reactiov1(0 t i0 pv) +feecag0mfs+asns?

  Which of the following correctly describes h4 66blm0 unujb)h9dkphotosynthesis or respiration?

Many enzymatic reactions hcn (:0)ywox4 e12jgkbmco*jhappen as pathways involving multiple steps and multiple enzn j j*ho) cocm4(eky :b0wg2x1ymes.

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

  Which of the following best describes the inhibitor in the image b0v *,ye urqbwa6ua bn405ahzem54 y.v elow?

  Which of the following statements are true regar m x;q7pc/7ttadkw*p*34/m cy,d,s*rlt z c ending regulation by end-product inhibitc*c7/d /zn*w xycm,lt3qk atp*s4pdm,t 7e r;ion?
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 enzr id79(w.hqrs yme. The darkened structure in black (r9.7qs irhwd 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 b z- 4s,j5(lzm mkdcho/e used to study the effect of temperature on the activity of ,dlz (jshk cmz4-m5 /othe 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 inte) -bat8qm md1bbhrd8zd t6) j5ract with substrates to cdq8r mm1dt-5bb8 dhab zt6 j))atalyze 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 measu.f ))cpjec8ll r( pz6ered.

  How does denaturation change the jf37 m4f l7fjp5a.jklw 2ixm9 properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statemendtgo9goz)8gh g38ne ;9 jt6ze:9 yqsjts are td 3)y8ggqegoontzt6h8 9 9sjze9g;j: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 characteris36ji7(r8grs1g( 6 zppi ryktetic that separates mammals or endotherms from ectotherms that have fluctuating b6p jpr3(18grygz (erks iti76ody temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine-kijrr)l6am( +g x yx4vjhn34 consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucm ly 46)gvn(kxax-+ ij3j4rhr ine 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 rxrhsf8g ;/k- zia;*-ey.e nhfol)t; eate of an enzymatic reaction. What is occurring ; gl)*-x;e y/ef tefzho hkirna;8. -sduring the phase labelled section X in the graph?

  An experiment tests the effect of changing substqu66k omog*6w,lf m4nrate concentration on an enzymatic reaction. What could be thnlo,m ow4q u*6gkm6f6e independent and dependent variables in this experiment?

  The diagram shows the pathway that conver h11h3iuu zkjkbdd,d f .s,8tzlt +b3:ts 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 w8g:x paz2g o m5zcac+ja2t0i.as compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-a20.aa2t ajx iz gcm5cpo+gz8: xis).



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 wt pr5 0*/ vz4cytf0ze hh73h5maridi 5ay to ke p57mz0thfi4 yc*dr/v5 3ih zh rte5a0ep enzymes active for a longer period of time?

  Which of the following describes some types of extrak-tsatvhiml / 2w 3c9.-se )zzcellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptide hjih7q5j8zb6g;hp/jz3i+gs s in the stomach. A study was carried out to determine the effect of increasing substrate concentrati+ ii jph/ 3j ;zghhq5j6gzb7s8on 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 off)6nnidm. mm + 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 curve marked A coincides wif6nmd. mn) +mith 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 a8 6ps :aqvih4ntlyq.c+w 78x*m alh57 llt w/kctivity, a student cut a turnip root into small cubes. They measured approximately 5 g in a w: xhmlc7tv 4q+twkhl*sl/q87 wn5pa.la8iy6eighing 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. Im(/o 4 lbofy(lnhibitors to the enzyme HMG- CoA reductase cy/m4(bflo l o(an lower the 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 followi5q+9dl5 t7h )javo6ni 1podtnng 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 meta/ pu lq2;od-bne6k97/xy2fxzfmr4vng 60 kexbolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabq f - xe46gn n z26;rxyod9fx/blmk/pveku270olic 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 e8 o/tddic t2nl/jb /m8 :to8dpfficiency of lactase activi2 8o/t8ntt/oc/mdd l8i b :dpjty is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a spes2buc i nkd9*,(qdm sb6 siu4: 9yt0wlcific lactase (Bg10), analysing the e0dq2yc( ksnu 9 s,*l649sdi :tmbiwbuffect of pH, 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 drugs for treating pa.wspl rjm ,,a0tients with malaria. Deswmp, s aj0lr.,cribe 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 enzym:y*/fn0ww f03j xvrdue affects the rate of reactionrfd:y/n*w3w jf0x u v0.
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 synkpzdmo1(1p l:1 78sfs kvxlm7thesized through metabolic reactions. Which type(s) of metabmzvl fsm1 7o81d7ppk:k(sx l 1olic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differ rxm06d a6snp:ent ways the rate of enzyme catalyzed reactions can be measur:max rpdn606s ed.
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 chemic1u36ea b4k vfas t6m;qal reactions, given one exampleafqeuma43 t6 k; 6s1vb 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.