Which of the following macromolecules describe a typical ed mw/t ye: o;2bhar+ihc9z)k 8nzyme?

  What type of reaction bl2pd/7s9m obf,10dt*lzk pw is photosynthesis?

  What is the substrate for the enzy-d.zp 1r.ch29v1ysdc u tnf(tme lactase?

  Which of the following stages of cellular respiration takes place in the cytotd- ).t)zzw cxplac)dtx)t- .w zzsm?

  Which of the following would not be useful in determining the rate of anxj 8, hh8o )fd6sfvhr9 enzyme-,hjfh)xofh8v6rs9 d 8catalyzed reaction?

  Which of the following processes ma ylen 31bnr/t dq8(uj;kq5 y6ny be described as catabolism?

  Which of the following statements is best depicted by theu0 vv a3ik.s 3e,qm8km figure below?

  Which statement about enzymes is not true?* s /z k:hjsrn+uay:l3

  Which of the following graphs best illustrates the r th:vlj*7. hmqmevlex;j c9:6elationship between temperature and the activity of *e lv;cheh:mm9.jvq:jt 6 7 lxenzymes such as lipase?

1.Sketch a graph to show how 7zxs:-ttd:k6 vn)-xxo b ojq. increasing concentrations of substrate affect enzyme activitvq s-ztoxx7t)onjx.k6- bd:: y.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactionul: 80p,ridh k:s,jj:1nd m2+mf yguvs. A diagram outlining the Calvin cycle is s ,v:jmr:1yl +2:0jh,pmidgk 8fdsunuhown below.

The image below shows t )fu9 sy6qnix-he catalytic site of an enzyme. The substrate is shown in black and is bound to the nxs i96qf-y)u 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 enzyme catalpntd 5 98f,imp ,gnvn:ysed metabolic pathways shown below? Letters represenpmn:fn,i,gn9p t dv5 8t various products of individual reactions.

  Which of the following describes the role of inhibitorsj*b 1;t1sy) k9kq vwpz in enzyme-catalysed reactionsk11z;qtyk)*9w jbspv ?

  Which of the following correctly describes photosynthesis0m 8n5.b6ly -xubmqdeqrw7-q or respiration?

Many enzymatic reactions happenq9di,: he4ney;8j bbw as pathways involving multiple steps and multiple edie : 9;web48hj ,ynbqnzymes.

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

  Which of the following best describes the inhibitor in txyy mmu80fn ;2he image below?

  Which of the following statements are true regarding regulatq)pv1qc17 epmxa *gka j 3:g.nion by end-product ivq3qk gj1ae1p.p7*n a:cgxm) nhibition?
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 darken54du, 2hio9v2gi wp ined structure in black iigw,u 2ho24 i9 5ipnvds 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 activo*2ab8d .wkbg2j+zqp f gg,s(ity + *wkb (s2q zbda2j.ogp8,ggfof 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 hozf;)sk 4w.fy pw enzymes interact with substrates to catalyzpffz;4s) y.wke 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 cat; 01yp9oqg;jm51o3oloe pr.a(kaiyj alysed reactions can be measured.

  How does denaturation change the properj0b5 ayaf88 kec(,a pities of an enzyme?

  Enzymes play a role in catalp hy xqogc/49/ysing reactions. Which of the following statements are tru4h/ox g9y/qpce?
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 ulk9 6nkqkyb;2ro l97*p dva9 from ectotherms that ha olb*6lp97rn;9ydv au9qkk2k ve fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product isob3s eu4 gom1byjed.. 7leucine consists of f17 gjumy .4eedbo 3.sbive reactions. Threonine is converted to various intermediate 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 increasing pH on the rate 2blofb i* v6-lof an enzymatic reaction. What is occurri l6b -oli2b*fvng during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an fx evio-kp0 y++86jdoenzymatic reaction. What coulve+kdyx 8poo0f+i -6 jd be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucinlvc u852 hc.pbb *+(0g qsmibbe.



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 activit+yr8hjf ax0kp04 fer 5y was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-axj a pyr04f50efk+xr8h is).



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 wawvw9 4/0pm 0- bgecoimy to keep enzymes mc / -400piemo9g bwwvactive for a longer period of time?

  Which of the following describes some types of extra3wez z,rm/5bk 5iw +zmcellular enzymes?

  The enzyme pepsin hydrolyses proteinso1l piyvj 92qkg6zm 022 c1(oghk4xfd to release peptides in the stomach. A study was cf kyh2ldo1vg2 4g jx21p(kz 96qic0moarried out to determine the effect 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 rate of reaction of an enzy;tdi 8yk5u-urxrt2 . wme with increasing substrate concentration. Similar concentw5u -t8kd; y. u2tixrrrations 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 enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cutheg::7 :*vr)zpr md -1hjfiim a turnip 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 and the liquid extract was stored in a test tube at )1emgd i imrf v:j:p7-hz*:hrroom 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 o;; klwf 10mapth2-.1hnrnwkto the enzyme HMG- CoA reductase can lower the production of choleswkn pwl- .1k12;r a0mfnh ;tohterol.


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 invco j hz i 366raxkz;5 pwwse+6j4/dgd.olved 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 mety r3anvtkn 7942 (+z rdopsak6abolic reactions in the classroom and were given an experiment which demonstror7za( + yar69tk n34nd s2kvpated 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 theym,/slx.io 5q):3dal a d3q2g a u,qicu/j +at efficiency of lactase activity is tested. Which is an appg 3+qd,y/,la2ai)d3/5uj.qax a :l oct uism qropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10),zp, y4jdm ,c22ub bug* analysing the effect of pH, temperature and glucose concentration, as it may potentially be u 2dbju c,u yg2pmzb*4,sed 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 patien10.bt,/ z ogfgv+qzqkx:+ ifnts with malaria. Describe how anti-malarial drugs are being discovered withi+. q b0 gnxf,fkq1+:g/ozvt z 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 rate of v,;le wmin7a+rg)y f2reaction.2yle)m7r a;,+ ifn gvw
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 uut 6i4e:abf.iy2)dc reactions. Which type(s)4. afyubidet2i6cu:) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cn m3 k*adauhdh83zl2.atalyzed reactions can be measured.h.kha 8 3d au*dznml23
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 eld6/4u wp,-r c4yexnxqyu/b /xtracellular chemical reactions, given one example of each type of reactionp-4 yre cx/u/64,x b/qy uwdnl.
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.