Which of the following macromolecules describe a typical enzzn ufji-gcj) kz 8ium,8b -7g:yme?

  What type of reaction is photosynthesis(qhrg;un9 b2 c(2yd3 wxr ke5y?

  What is the substrate for the qoy5brm;q ogu(/28trk4 8x6jqw dq/ denzyme lactase?

  Which of the following stages of cellular respiration takes place - 0pncindol(/ w3u9plin the cytoplasm?lnc np ido9l-/p30wu (

  Which of the following woul5xde+r , t;nvzd not be useful in determining the rate of an enzyme-catalyzr; zdx,et+vn5 ed reaction?

  Which of the following processes may be describ luam/ i0)r- .mqc*hmued as catabolism?

  Which of the following statements is best depicted by tzc5 ee ofc4q0j,e1i e,he figure below?

  Which statement about enzymes i6zvdkrq(q2/ xg1 jdp:mq(0sxs not true?

  Which of the following graphs best illustrates the relationship qtd;e3o0u.mkq u 9yb. ao1a x+between temperature and the activity of enzymes such as lim 3.;aautkq91.ubq oxed0y+opase?

1.Sketch a graph to showz vb t1dwg3br+g( :, tce4: o/oppsaclssb4, / how increasing concentrations of substrate affect enzyme a+ lo(4// ,rpbggpcs bb :d,13savc so :wtz4etctivity.
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 diapgdb*fl-5 td tjzk229gram outlining the Calvin cycle is shown belo-2tzbd *t5lpf9gd k2 jw.

The image below showso3wy7wgjft; ( the catalytic site of an enzyme. The substrate is shown in black and is bouf3w;ojy w7g(t nd 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 f-f ybr ;nd1u jq (z8nwf 3-c:dg7d6j +.jcmjithe enzyme catalysed metabolic pathways shown below? Letters represent various proym+8ifzj;qj-7 n-1 ffnjdjc:d36c.bw ( rgdu ducts of individual reactions.

  Which of the following describes the role of inn b9+tlmse/b)5g b2ttc5 w. muhibitors in enzyme-catalysed reactionbgt5 lb+sb). m tt5c 92n/uwmes?

  Which of the following correctly describes photosynthesis or respirationnz3 nsk, r/yjs, 7ag4x?

Many enzymatic reactions happen as pathways involving multiple steps and mul 96+ sgmfptv5ymdn x9(lv3hru2 2 p)wgtiple v 26m u3+ ghyv299wt(slm5fp pxrgdn)enzymes.

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

  Which of the following bgyf:;y 8 dlsr3est describes the inhibitor in the image below?

  Which of the following statements are true regarding regulatiod-/+f evh byr)n by end-product inhibiterv b )/yhf-+dion?
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 shl:thpg bpl;w3f 8 (z3uows the structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bounfu: 38plw; 3lh(gtbz pd 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 s qj)gc77; 38 3ba qiloseg u4o9lfp6hz01j brthe activity of the enzy o1juqj74qs 3 8ze 9pgb ia;bs0l63c)f7rglohme 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 interactm vzja-:. aywg)y3w 9h with substrates to catalyze reactionw9g-:.yhmwz)av ya j3s?
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 catal4p 6gxnf0g+ tid skbz:zo (7c1ysed reactions can be measured.

  How does denaturation cha8zb9y .zho)8/hi.e(lh-if.otn fu tinge the properties of an enzyme?

  Enzymes play a role in catafa wl51:v7dh zi sd1,plysing reactions. Which of the following statements are tr57lfsdzihadw p ,1:1vue?
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 mam j k df+upx;,o(rd2ggz-q0e x2mals or endotherms from ectotherms that have fluctuating body temperagq(g2rf edu+,0 o d jp-x;2zkxtures?

  A metabolic pathway that converts threonine 2 z67id *p:ig r2mmhmsto the end-product isoleucine consists of five reactions. Threonine is converted to various intermmipsr *mmz262 7 ihg:dediate 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 increa b ;)bmfsaxss3kt9a,gy ;1c: :jx/woqh l: ow3sing pH on the rate of an enzymatic reaction. What is occurring during the phase labellwtkyqs1gha9a:s ;)lb xo 3mfb,3scoj;:/:xw ed section X in the graph?

  An experiment tests the effect of changing substrate concentratikc)kz u9)2f xdo:t hb,tm0v*q on on an enzymatic reaction. What could be the independent and dependent variab2b) ,ztc:m*xtk )d hkvfo uq90les in this experiment?

  The diagram shows the w9iab/cr. p,jld,drw9kn39- r fl* fanb8wi5 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) waskc)kg/xpp2d3ncip.h lp 2:2a immobilized on 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 (x-axis)k/ :pphncp 22l.d32k)icgapx .



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 e,uza9k3 tyj3ba/+u fthe following is the best way to keep enzymes f9abk3 3 tauez+u,j/yactive for a longer period of time?

  Which of the following describes some types of extracellular*d+dt oax p cu39)6xpu.wnoh / enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach.csbu8jd(8nxp z 4z1- v A study was carried out to determine the eff 1zbx8d c8j zvpu4-s(nect 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 rat9agwn7oij 93+(ml khw e 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 curve m n99 waok(mh3j7liwg+arked 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 turniyszrh(:q8hwybf6 ;i 0lx8jo )p root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The homogenate was filtered bji yh0 8:h)sr;oqz x(wy f68land 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 i d*.+ktrmx/8 ws siu0fs shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the productm f xi+*ud./sws0 kr8tion 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 are involved in denaturatd d 5(l2 rpeey+wu2/9u5cbx)-af k rajion?
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.4 lzzv t9pp cl vv0b5s9cdb*, the classroom and were given an experiment which demonstrated the effect of tempep zpbt. v9dz5vl,clcs4b*0v9 rature 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 temp ,7mdjm/t2f.vjy2gex erature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for th 2d7mvgx.jej ,y/m t2fis experiment?

  A study has been conducted on the activity ofu,6k ykf8* dbffg*(.f;rcxi9x d dcbz 6eh c77 a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially bcrfgdcx*kc;z6h uy7xe f* 8d( b f69kidfb. ,7e 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 findg+cu0xr y1g42cbo ogwja2*96 1 arpjy new drugs for treating patients with malaria. Describe how anti-malarial drugs are bei j6yjg *2o2wbcagpr4rg cy11a0 xu +o9ng 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 rajg m/, hwfs*s pksj3;eq+:o3jte of reactios, ;q g:mo/ks e3 jjw*jpf3+hsn.
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-t3kg*q f0gg+dh ve .w down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are cg q+3*v-.ghfkte 0wgdondensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be me*yq6 ;ttjm4 :soa pxpi(yyc-/asured. -yp 4;y /(iyxmcs* j taqpto6:
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 intraco p e z1tqciu76ek u5u3esw,(;ellular and extracellular chemical reactions, given one exampleqc;s 5o6u,eeu7 pi uwt k3ez(1 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.