Which of the following macromolecules describe a typica,wyl k9japt6bo,5no +i/i n,cl enzyme?

  What type of reaction is photosyn89i yx8dbqp/39adoq+bt3gbqthesis?

  What is the substrate for thet*s47c.5+vb m1klct nn 6 ft)a ar3gqq a+w5pd enzyme lactase?

  Which of the following stages of cellula vh hj-j) brhsqge 6,ejxnm5.)o6t19ar respiration takes place in the cytoplasmhe9rx -sje6b.q vj ga h,5)jo6 1tm)hn?

  Which of the following would not be useful in dete02s.fy:gabqn 91c7o, tnl8cbbig:tc - q um6ormining the rate of an enzyme-catalyzed -s,t60lq m9acy8o g7q2u f bn::b1b.ocni tgcreaction?

  Which of the following processes may be describlp- h,qhgw2 +qed as catabolism?

  Which of the following statements is best depicted by the figure brq *fbsro 8,/q.sgn 7-b5waokelow?

  Which statement about enzd6;xqcyx: s*x ymes is not true?

  Which of the following graphs best illustrates the relationship gu l rozu4kohy7kiy 9 +1cfz2* 4a3;ehbetween temperature and the activity of e4 ey*4if7h ulgo1cy;k + a2kz9zohur3 nzymes such as lipase?

1.Sketch a graph to show how increasing conceno37r7 rjinnp6 c) svc1trations of substrate affect enzyme actcn3)n c 1j67v7pi rorsivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of en 5,yv9r+kc iwqzyme catalysed reactions. A diagram outlining the Calvin cycle is svk r,+9y cw5qihown below.

The image below shows the catalytic site of an enzyme. The substrate e3q8 z sj9m0 )jcbq:in91gqcwis shown in black and is bound to the aczes 0j 9jqcb):8qw i9m3cqng1tive 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 enzybk77gi2b2(yjm netp 1 me catalysed metabolic pathways shown below? Letters represent variou1(ymnbigtpj27 be7k 2 s products of individual reactions.

  Which of the following t f3qm.u oh062s dks-bdescribes the role of inhibitors in enzyme-catalysed reactioh.uofm td23-s6 kb q0sns?

  Which of the following correctly describes photosynthn6y1f sw1- ;sh;v bcyhesis or respiration?

Many enzymatic reactions happeaa+og.h1i5jyf r( ot ruqd) z:+xq 0;wn as pathways involving multiple steps and multiple enzyj5)aq r (a;x+uo.0yhftzg ioqd:1rw+ mes.

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 below 8l;bo g ,/agyowt4:p2d/vfhn?

  Which of the following statements are true a7v.l1;sz 6ah)ufuey a dop+6regarding regulation by end-product inhibition? aa1ldv )6heo.f ps6yz; a+uu7
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 mpk769*1m vwi al z-nvv(p0gvstructure of the lysozyme enzyme. The darkened structure in black is the substrate kl0 *6vw vmi7pa9(1 pvvng z-mand 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 t pmge;i quc/ l,d53e(qemperature on the activity of the enz5qe/ 3qlgmpd ; uec(,iyme 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 desc c5gn*cvk)ht /ribes how enzymes interact with substrates to catackghv/ )n t*c5lyze 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 measuredj 98lipwc,i7x z5u)eh.

  How does denaturation change the properties of an enzyiw 0y 0jum+; tv.in;ckme?

  Enzymes play a role in catalysing reactions. Which of the following statements yo:3(7fx: nbhnu3: zz3/ vmrcdwa7i fare true? 7mh: do:uwznbf 37(:nyz3r/x fic av 3
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 sepa*k.xip8u 1qxj1)k)zmvb :zr grates mammals or endotherms from ectotherms that have fluctuatin .rgm)):v kjx bq*11k xizpz8ug body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine consxmqko)qo 2a clh:qo pvqu 2c+.a2r+9 (ists of five reactions. Threonine is converted to various intermediate productsoq2hor:lau9q m +xop +c k22q qv(c)a. 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 rat+d 4uy 4dqe 5ah*ej:fqe of an enzymatic reaction. What is occurring during the phase la4e*54aqye+ujdq :hd fbelled section X in the graph?

  An experiment tests the effect of changing substrate concentragtl/h icssq+0m : ;o1ztion on an enzymatic reaction. What could be the clzim qog+;h ts1:0/s independent and dependent variables in this experiment?

  The diagram shows the pathway that converts r,u c +l/-oedsthreonine 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 mt .3exb:n +e z/)56beia:bz(gz ihwqnatrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with )nh:ie3.ezb56/+(neb:ta bz x qgwzivarying 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 easily denatured. Which of the following is the unogf d5kq.(wg**4c e9:t nvzbest way to keep enzymes active for a longer *59tnwv(e*uq:ofd4.z c ggnkperiod of time?

  Which of the following describes some types of extracwcl5;zlf5 h7p bwy6p *r2zdm5ellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in +0g dxxblh/w4 the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a consta+xg/0dbh l4wxnt 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 ow m1x p jt r(tcu:,wnk s+en5u4-hxk.)f an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, a+x)4mnj1u,wswn (c- pttrh kxk.5e u:nd 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 s9 dv)celk 2nwnn33s f(ncjz*bp4 .uj4tudent cut a turnip root into small cubes. They measured4pcfn)nkjw3n z en*4.cvjs( 9 ud b2l3 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 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 bel4o fx5y6 :4lgpuaytk, ow. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholesterogfa k,ly46txo u5:y4 pl.


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 i+ f5 6xf5rz g6zbzqq;bn 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 metabolic reactions in the classroom ana dk cjr 27k44mlfr kuoy*n0o9. bta.(d were given an experiment which demonstrated the effect of temperatu k7* obkla2onk 4y mt.fr(jad9u0.rc4 re 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 the nb6r.+6c wwfb1x am t9a*ak/qefficiency of lactase activity is tested. Which is an appropriate depenrcqw6a9mt bf/6w kx n*+a ab.1dent variable for this experiment?

  A study has been condq /gq1l 7hzty9ucted on the activity of a specific lactase (Bg10), analysi1l9gy/ tqz qh7ng the effect 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 needg0j kh r;qa4-r to find new drugs for treating patients with malaria. Describe how anti-malariaah0r-;4kqj r gl 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 a(sd mqv)kmh 7r t 2pd:/is37;/zjrpunn enzyme affects the rate of reactionq mz:p7k rids/rmvp 3ds tu)(7jh2;/n.
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 reactioq*k n( sqm-00snew.0 kn7p emsns. Which type(s) of mq0e pqwsens.m( 7-k0 *nnk 0smetabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be (rqj)ndi++9jxgwv v; measu qn;g+) vd rjjxw(+iv9red.
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 chemical reactions, givep7 1m(cx7n+m1la(+wh *-g qq x yghkqsn one example of each ty-phcx(71+mhg mqnal sqqy w+( g7 1*xkpe 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.