Which of the following macromolecules describq9 h qbeaumo; /0, w+sf8tmc0ve a typical enzyme?

  What type of reaction is photosydcxik4 w7 p2l5w)v1 o9fylwc7/idra,nthesis?

  What is the substrate for thejb0n2fnm um).q rx1yl,y 2h.k enzyme lactase?

  Which of the following stages of b; d1g8j+mxeq cellular respiration takes place in the cytoplasm gqbj+;8ed mx1?

  Which of the following n+c 0wflz9ao- 3cf7jhwould not be useful in determining the rate of an enzyme- 0 +c 3nj-lhzfof97wcacatalyzed reaction?

  Which of the following processes may be describj,n y (yy27iyztu/ry1ed as catabolism?

  Which of the following statements is best depicted by the figuren-pmk83wiz+ 91 4 cgejn14qe 8acqhvz below?

  Which statement about enzymekflj5j 4tkfhqr/x 2s .7,xr9 qs is not true?

  Which of the following graphb sws jom0g 7uk),2f/07u1ecpubbb9bs best illustrates the relationship between temperature and the activity of enzymes sucusb u7jg b/e o0,w9cu702fbkpbs1bm) h as lipase?

1.Sketch a graph to show how increasing conc l87hfzc-1f8xd/*ac 2ceuqkjentrations of substrate affect enzyme activc ha7 qce zu8-j dc*x/l1ffk82ity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a se-tnky on*aaf( 0u,n/ rte;q+ +ebbp(d ries of enzyme catalysed reactions. A diagram outlining the Calvin cycle ny,tb+a na qeuk*e bt (+f; 0/-rpd(onis shown below.

The image below shows the catalytic site of an enzyme. The .s x0ef,o (vav1hxwns(vqg*set)8 k +n64zb osubstrate is shown in fxhex, o a z8ew*+(bvs .4kgnv(1sn)0tvqo6 s black and is bound 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 deybkx * :jta :zd;+ht9jp. ;jytscriptions of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reaay;9: bzd h:jj t+x;.jktyp t*ctions.

  Which of the following describes j(k42pw)yq,atp i m. :m-i 7fgqqi0w i8d-qpcthe role of inhibitors in enzyme-catalysed reactqq7 pw8pj: imd4aft (qi ikiyp--2c)q.wg0m,ions?

  Which of the following correctly describes photosyntnubj* t 0gel/-x7o p,mhesis or respiration?

Many enzymatic reactions happen as pathways involving wtm (vp218c pfmultiple steps and multiple e2ftw pm8cv1( pnzymes.

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

  Which of the following best describes the i q:m32pqxcz5/tk 0*axwbie 3vnhibitor in the image below?

  Which of the following statements are true regarding rnurg w9nw e703egulation by end-product inhibitioe g3wn9nu 0rw7n?
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 lyk. o* e.kch : w+ybw dq)fhmf*-/u1afdsozyme enzyme. The darkened structure in black is the substrate and is boun+ f:m* *k)d-ywho.wdh/efakcub q f1. d at the active site.

Which of the following characterizes the active site of an enzyme?

The equipment below can ,nx u 9yt8t rctiz-jhgi0b0 1h/ svw46be used to study the effect of temperature on the activity of i0t t10/u4xt9js wzg8h6b,hcvr-y ni 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 stame c kcm,d)nnf:a; k-(tements describes how enzymes interact with substrates to cfn k-m;emac ck(nd),: 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 /0 ki b8qxrs)xmeasured.

  How does denaturation change the properties of an enzymh see;uy8 h8 d 8bgnze4d/ky6:e?

  Enzymes play a role in catalysing rea) ;9em va1jc)ckhb 8zcctions. Which of the following statements aze8 c)machc ;)kvjb91re true?
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 endo7wr j8 ,s.5f* boq+pikmm*wpd(vp no3j5 x5 jmtherms from ectotherms that have fluctuating body temperatures?w5,r873mm*qj5x fw jv+ jm(b*p iodsknopp.5

  A metabolic pathway that converts threonine to the end-product isonvu/f)i6 lajxb5 p) ax -gl+2vleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isollf -)6ga/j 2axv +ibx5pl)n uveucine 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 of an enzymam)g5vd 9zobgpv9bu 6ff- :xh8tic reaction. What is occurring during the phase labell8) uhf:9f 9m g6p-5xz vdobbvged section X in the graph?

  An experiment tests the effect of changing substrate concewfb7 *r t:r8csntration on an enzymatic reaction. What could be the independent and dependent variables in this experimewts*7 brc8 rf:nt?

  The diagram shows the pathway that converts threonine to isolexpxej 9thewd)) ,e8m 1j1 0iatucine.



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 acti4r+ac(k;ts fkvity was compared with that of4t(a c;rsfkk+ a free 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 easi2v+q gyk /d :8:d*s5p+ipv jzl gr*kimly denatured. Which of the following is the best way to keep enzy5ikd:gv d2jkigp*z+8 p+:/vs mrqy l* mes active for a longer period of time?

  Which of the following describes some 8 ggukh .l3w6x(fq+bh types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A y vmj3pkako7o4* t,h7study was carried out to determine the effect of increasing substrate concentration on enzymea4ojo7kyv* k p,3mht7 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 enzyme with increasing sub k6 (u5m xqjk qukj;ez7zx1+b7strate concentration. Similar concentrations of chemicals A, B, C and D wqqub ejz+71kzxxk m(7;6 u j5kere 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 cut 8d1(jv c1 zak t:i;xn25mroina 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 en o;d1ciz1vk xr najm258it (:xtract 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. : s v.m6ztx ys: nx3nxc*3ip(pInhibitors to the enzyme HMG- CoA reductase can lower the productio3:cv:mx.p3 ynnxsixt( sz6 p* n 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 a*ayikaey159 8,m u t3 wz:snrmre 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 metabolic reactions in the classroom and a.+)ou kn1skt were given an experiment which demonstrated the effect of temperature on a catabolic reaction.)+o t.n1as kku
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 on6fv lon+8;asw * yt2wf increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable f w8o2 va;n*wflt6ns+yor this experiment?

  A study has been conducted on the activity of a specific lactase (Bguzi1ncn*kee/o3 25h:w;w k aq10), analysing the effect of pH, temperature and glucose concentration, as it may potent3nchw e/ zawu5q;i* n oe12k:kially 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 patioe- 0l-7bw+ e; ge3 nlcmy+oqxents with malaria. Describe how anti-malarial drugs are being discovered with new technologiem ob0xoqy e+l+g -el7wcne3;-s.
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(1tl ky0ll /bzs:z,wv of reactionszl/btw,0zvyl kl1: (.
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 reauu+0de pq)amkcy 4rs 6:q;w 4vctions. Which type(s) of metabolic reactions are condensation ra)k:ymqvrwc p qde+60 4u4su;eactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed rex8 )fl8wmi-2ifs/:hoiurl9jfe 6 uz7actions can be measure7/jf:i8 8u9f2 zhsw fimxl-ur)l6 o ied.
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 extr6zxg0mi9tw( lcn0q00sjd ) 5 qt6uxcyacellular chemical reactions, given one example of eacysl5xtj w dxqz 00n0cqiu6)69m0tg c (h 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.