Which of the following macromolecules describe a typical en2lmt28u:l(efe vsjxx v6d1. m zyme?

  What type of reaction i5b w 1gp(c+voe;go5rss photosynthesis?

  What is the substrate for the enz/5,vqymag alx t9n /*vyme lactase?

  Which of the following stages of cellular respiration taky ztl :kk)2xz2es place in the cytoplasm? )zkx2:y zltk2

  Which of the following wou 8po.im0n(tnfld not be useful in determining the rate of an enzyme-catal.ptm0 8i(o nfnyzed reaction?

  Which of the following processes mt d*guw, -*) k:cm6 r+apmb6mm-umucnay be described as catabolism?

  Which of the following statements is best de:22my* z )uhebe+vphjx hpm( 6picted by the figure below?

  Which statement about eaezda n6 ug- +z3o;ca)nzymes is not true?

  Which of the following graphs best illustrates the relationship betweeuyfva(j/ ; q(.cca)g bn temperature and the acb(f; uv .c(gayj)q/a ctivity of enzymes such as lipase?

1.Sketch a graph to show how increasi*ut 6hoh,/ysh5 q()xuwwecz;ng concentrations of substrate affect enzymecwweh* ,6t(u z s;xhuho5)q/ y activity.
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 dnmzug h,-tw q d:.8jz/*xf4rmu 8a*m wiagram outlining the Calvin cycle is shown below.r- uxu: 4/nmfw8ma8 gzmd. q**twhj, z

The image below shows tc049b(nh2jf6j 9k, tb fp dwonhe catalytic site of an enzyme. The substrate is shown in black and is bound to hcnpn j0bt6oj(4d9b wf, 2kf9 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 the enzyme catalysed metl- tqd x4ups//abolic pathways shown below? Letters represent various products of in/l-xtuq 4/ spddividual reactions.

  Which of the following describes the role o+p+39don)s rej;hb lff inhibitors in enzyme-catalysed reaction+bn); lrefd3ohp s9+j s?

  Which of the following correctly describes photosynthesis or rey.c:n11a stzwk*; hymnwq38 hspiration?

Many enzymatic reactions happen as pathways involving m*lp78ghwepw 0ultiple steps and multipl gp8p07e* lwhwe enzymes.

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

  Which of the following best describes the inhibitoycse+ qi c-l7) 8d0pzgr in the image below?

  Which of the following stm, l:uop9ui0aszx+ ( natements are true regarding regulation by end-product inhibition? x soa 9uumli+0pz:n(,
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 darkened str ) z.xlw;t76+yuqjwqzucture in black is the substrayqz.x wz ;t) jwl7+q6ute 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 ;tq34 u0 et1)xg xxtgltemperature on the activity of tht;gg0 t4xxt l)1x3eu qe 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 interact with subsi c2 iem25qbx q s+5)pfj/1kzm cp5ss5trates to catalyze rejs)pmc5 5/scmpqifb5z5 2i1 xqske+2 actions?
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 reo6ie cd(lg)-; p3c nc uwpml(11fdi2qactions can be measured.

  How does denaturation change the propertie r;nr,h m5m:qz*qky s p1z3 g8xz.r2tus of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stateztl yfkp3w+;/1s xk9bments are true? z1 kp bx/y+9;swt3k lf
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 endotherm*j ub r3x;d /pa:nb(wes from ectotherms that have fluctuating body temperature3wd;a/ jne rupb(*b:x s?

  A metabolic pathway that converts threonine to the end-product iso w/l gulxv*h-hpc-3g+y .ku j2leucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by tgp+- uyxjgh*/hl c l3v2w.ku-he 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 2,q+oiwsq ;tgwdxd.) nj(:l wb;.xxhon the rate of an enzymatic reaction. What is oxinh,bxwxoq: d lj;.gs+ t)q2d.w;w(ccurring during the phase labelled section X in the graph?

  An experiment tests the effect of chaw0bt5h bm9 x(cnging substrate concentration on an enzymatic reaction. What could be the it0mwchb 5(9x bndependent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleu gcd3g mjmqf+tfq2tbi/o+(9yhn/k ) 3cine.



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 actgvt c+g q1s.) n ks2suntpi1(,ivity was compared with that of a fr u1+sntscgtkpq2i1sgv.,n )(ee enzyme in solution. The graph shows the 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 easil*lrxvu-pr8)k 6 mza 9my denatured. Which of the following is the best way to ke)l6rmpxu* - va8z9krmep enzymes active for a longer period of time?

  Which of the following describes some types of extracellypp+ 7-*irgdwr t7 ph3ular enzymes?

  The enzyme pepsin hydrolyses proteins to release pepez u1e zt. i,z704q8 v0k -*ortknnlyptides in the stomach. A study was carried out to determine thq .k zv*o0p40tkrz,y1i8 nul-entez7e 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 rboy;qy,6tqiwcglt : xl4-u;8ate 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 marked A coincides with the activity of the enzyme with no inhibitor :q;ltiyyu4 86tbc;l w-qg,o xadded.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity1f-g dw3di:p(j-et ot, a student cut 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 tdf1oigtj--e3 p(: wd 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 enjc-y6.eexl7iq4z 8g b zyme HMG- CoA reductase can loweq lg7e4 -yxb6cz i8e.jr 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 following k- 3i6u7srctz 3aet,p 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 metabol);c/xiun o/z(1qp o jfic reactions in the classroom and were given an experimenn zf ;/)xciuoo/p1q(j t which demonstrated 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 increash( 7zhkj s:8h) inw0r(awe p.ring temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this experim rh)r(n.w0w:(pahhez jk7s8ient?

  A study has been conducted on the activity of a specific lactas)vsfo 4lyj2*ue (Bg10), analysing the effect of pH, temperature and glucose concentration, as iu*vjof2 )s4yl t 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 continuomvp 2f3fc()u,,zctivzbl m *7us need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs a*m ,72)blczt3 pifm,( c fzvvure 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 increaxizg8k(yje.oj7v 02 z i07wvpsing the concentration of an enzyme affects the rate of reacti(0 w j2xe0j zkvv8ii.y 7gozp7on.
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 synthesw4ze37u+wki.+x7 shqy5n, /ig y pthn ized through metabolic reactions. Which type(s) o7ei hg,h3i74kw+p/zyywx 5 +n t usn.qf metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different1fk-t 1kp:96wfigz/uq ppbm )ui2sf 2 ways the rate of enzyme catalyzed reactions can be measured. 1gs:ki/tu ppum )fff-qpki22w6 1zb9
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 en f,k(av+5l xvp4x2zj xtracellular chemical reactions, given one example of each type of reacx( vpaj425nl ,zvx+kftion.
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.