Which of the following macromolecukk+ l ;0q,cmtcles describe a typical enzyme?

  What type of reaction is phobypw/x 0 x,li1tosynthesis?

  What is the substrate for the enzyme lactase ezr9u qb8g m+)2rpil/?

  Which of the following stagu8xiwpbvfc/.ijh65+6 n c4*8yn y ti jes of cellular respiration takes place in the cytoplasm? i/8iyc8pf4n+vtwj. h xu5n6ci6 j*by

  Which of the following would not be useful in determining the rate of anw:v yfsy n)qso x36t/jk8x8y/ enzyme-catalyzed reac)kqx:6 y3syfsx/ yj/vo8nwt 8 tion?

  Which of the following processes may be des-l378bso 3e5vyulp sxcribed as catabolism?

  Which of the following statements is best depicted by the figurer hh:+k** glxi(qqy*0v-bsk e below?

  Which statement about enzymes is not true?h;g uxz2l udomg ,ja;f1. 2xx1

  Which of the following graphs best illustrates the relationship betwe.m(*l4wr/fwj r;lvq s en temperature and the activiqrfsl *m. j(v;4 r/wlwty of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of *a zd*grbb:rk7ms *z5 substrate affect enzym 7*z s:bamg5br*kz*rde 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 rexi98 qyn+4hu6 irw,sxactions. A diagram outlining the Calvinshyq46n+ rxiui w,89 x cycle is shown below.

The image below shows the catalytic site of an enzyme. The .lgf 6ftn.(n3jt-xk2 *suw eqsubstrate is shown in black and is bound to ln3s*tqku62wf j fx(-.gt n e.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 descrip wfn:5z /7u)bwhh0 xuckc(:sitions of the enzyme catalysed metabolic pathways shown below? Letters represent 7:ukzc) b 0c w/i xu(wh:hs5nfvarious products of individual reactions.

  Which of the following describes the role of inhibitorsw-zwa ey j5q+9lj h;f/ in enzyme-catalysed reaction y/lf-qhwz +9 jj;ae5ws?

  Which of the following correctly describes photosynthesis or respirati24 7lo/nvpxndon?

Many enzymatic reactions hapen/ttl18e* ng pen as pathways involving multiple steps and multiple 8n/neg*el1 t tenzymes.

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

  Which of the following best describe smlq 3f4d8(xgs the inhibitor in the image below?

  Which of the following statements are true regarding regulativ fe82 8kf gjz,v;gd:son by end-product inhib:; ,jf 2gv88 veskzgfdition?
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 strbwu:a /en9jo4h7uca9 ucture of the lysozyme enzyme. The darkened structu:c7e a9ahjuuow4n/9bre in black is 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 stz33r-e6n jitsudy the effect of temperature on the activityei3z 3jn- ts6r of 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 desqdw2 (k// ghze)+dn ,f qylx3ncribes how enzymes interact with substrates to/ gzf2) , q3/dleqnhx y+dwn(k catalyze 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 reac57y+ilux yc-hqharj;x 0uy:g6i1e a3tions can be measured.

  How does denaturation change t knhhg)j)s s.,a p+fu*he properties of an enzyme?

  Enzymes play a role in catalysifk,2,tci.p cvu 6 ,opbng reactions. Which of the following statements are tpk,,ucvpt6i, c.2b ofrue?
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 si od ojcoq4io 6)e55,separates mammals or endotherms from ectotherms that have f) 46ooo s5jieic,oqd 5luctuating body temperatures?

  A metabolic pathway t(6bh mis0w ;8x0j s zxxm3id1ehat converts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is conv0sw(s x31me8dm xjbhx0zi6i; erted 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 of an enzymatic reac;3nm- bwbgf6n9m o20 wk-bvr otion. What is occurring during t n9mw-2bbnof 3bvom; 0-rg6 wkhe phase labelled section X in the graph?

  An experiment tests wnw+k s(u.od+the effect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this exped.n o+u w+wk(sriment?

  The diagram shows the pathway that converts threonig8is6y0,ez g5 vr;pzyne 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 matrix anpww 4(y/nxe /jd 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).//e(n y4ww xpj



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 f*mqmi ( n+1q4rgi2ejpws/c 1way to keep enzymqsr (2 j/m*q+ iwpnegf14cm1ies active for a longer period of time?

  Which of the following describyo6u5xkq3vv6 es some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release pett7pxde1s i 6;sw:sh0ptides in the stomach. A study was carried out to determine the effect of increasing stt7px ssh06id e sw:1;ubstrate 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 enzyme with increasing subst7enxog 6u nn*,3zg0 xu; rh7gpho1e w.rate 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 tohze7 *wp o,0n xug; 3rgh.eux gnn671he 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 uw+(efnno22g 5ych /i 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 the turnip root. The ho2fn5wcine2yg/(u+ 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 enzyme HMG- nt x,-d ns)hna),zg:z CoA reductase can lower the productionn)znhsxg, )tn z, -da: 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 involvedt x 0lc8xlla8jp/ybh/h8s,l+ 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 reacn* /bdxx0es(x tions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reactio( d xn/b0xex*sn.
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 aji*jvdx25em1et t0 )flr,n:on the efficiency of lactase activity isf v1t ljjeed5nr a0,2m:*)ixt tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on el 7 gnh6kqrhdq3/ 9t2kt4k 36m(svtkthe activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may6ttv t kl39kh(kmnh3e 4gds/7qr6 k2q 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 need to find new drugs for 4)sx un*k,j)1tcc qcutreating patients with malaria. Describe how anti-malarial drugs are bein x)tu4sknu* c1)j qc,cg 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 concentratolf c*qy:(dotw 8s0w:fv 0p1 nion of an enzyme affects the rate of reactfv po:wfldwto1y(q8c00s: n * ion.
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 reactions. Wh2j9u es hy05zueq+mf. ich type(s) of metabolic reactions are comufy u qj.5e 20z+9eshndensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways tyc.w2bpu 7 sco34;hkwq25uouhe rate of enzyme catalyzed reactions can be measuredb22sok5. 7wu3h4u ;ywccu qo p.
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 chemica mc.)e5*bfhjbl reactions, given one example of each type of reactf5*j.mb)he cb ion.
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.