Which of the following macromolecules describe a typical enzymzfkt1 d44sss6e?

  What type of reactio ym copzo4/;js,jjd)y1z2*g i8gi pj*n is photosynthesis?

  What is the substrate for th/)jvu *egq n,cle9 u(ze enzyme lactase?

  Which of the following stcz6vxauup2k2 .2,dsjages of cellular respiration takes place in the cytoplasm?us x2v.p2j6zudc2k a,

  Which of the following would not be useful in determaq0 ;4hleet0xining the rate of an enzyme-catalyzed rea0tqx;laee 40h ction?

  Which of the following processes may be hwqwss sg: (,p*nxmsf+ 7p/x( described as catabolism?

  Which of the following statements is best depicted by the figure be7cz;v i:jc3/i+ftpvhukmt9ip +1)z 0nqm3n y low?

  Which statement about en1q(i r,o, jto/g;rbpdzymes is not true?

  Which of the following graphs best illustrates the relationship between temg9l qlpma/;u yzk- )c*1n/ql hperature and the activity of enzymes such asg ) c*hqny1lql-/a mk/9;p zul lipase?

1.Sketch a graph to show how increasing concentratiosl812vynvsg kc de :1,ns of substrate affect enzymec l gynvvs:,s8 k21d1e 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 h hy4(hy -i)t2zp,inereactions. A diagram outlining the Calvin cycle is shown he i,-i ht(py4)zyhn2 below.

The image below shows the catalylms tzxt-nsq)t60hd+0qj iz.. 1gv u.tic site of an enzyme. The substrate is shown in black and is bound to the act 6h.1zxd.)0tlzq s.g+-niv0t tm qjs uive 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 cataly1u: cr/.ohi ,b cc0ufcsed metabolic pathways shown below? Letters represent various products of individual reactihrubc 1 /0,.ocuf:cc ions.

  Which of the following describes the r)*t+8 kxbszek ole of inhibitors in enzyme-catalysed reaction* ksxz8ebkt+) s?

  Which of the following correctl;ndp y5.hb/ej y describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving mu b5f 9xh4d(01tot x.+,mt gketzcf*acltiple steps and multiplca d0 tkxo*x m.et5fh,ct4gbf1 +z(t9 e enzymes.

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

  Which of the following best describes the inh1 mq0r,rpb /5tb yomi)ibitor in the image below?

  Which of the following statements are true regarding regulation by end-produchaq-:jn6 l+zqz9tk7z t inhibit z th-lzq6k:nzj7q9+aion?
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 dar amhze84i(,dikened structure in black is the substrate and is bound at the active siteami z8( d4,ihe.

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

The equipment below can be used to stnqz*);tjg rt6b4+mu) v dpp 4tudy the effect of temperature on the activity4* gp;4mdrtnq+vzjbp )6tu) t 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 describes how enzymes interact with substratesxvilnq 8 kj l5e23n/*zb ict*6 toq85t6 zvc jnl/*ikbx 3*elin2 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 enzr : bywvy3l u+1w.s:dh1+mcgfbfq7(w yme catalysed reactions can be measured.

  How does denaturation change the propertjmdz9n;6 b; g6fgzn3;b3:pl5 hpcn(uvj,vn u ies of an enzyme?

  Enzymes play a role in catalysing reaff*blx6asil 8w*5d f:ctions. Which of the following statements are true?lai5 lsf8*:*6bf d xfw
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 ma6t: jbuv)qtdr*y: +trpx/-k)a; q fdq mmals or endotherms from ectotherms that have fluctuating body temperatures yk:bt ):dfqjr6+p t *xr avq-)/d;qtu?

  A metabolic pathway that con2ty (iqt :m oxll6m6r (i;el3gverts threonine to the end-product isoleucine consists of five reactions. Thl ml;( q:6xt ig6m2olte3yr(i reonine 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 of ah wj5k pbc:11vy,l vd7n enzymatic reaction. Whwj ,5: 7h11 lvpvcydkbat is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enz57o)bfs, cqo7)y jryrz,.co i6ackl9 ymatic reaction. What could be the independent and dependent variables in this e6. sz c75jl,brooc)oai97),yf yrckq xperiment?

  The diagram shows the pa n :7dtnez5ng:e4g9t nthway that converts threonine 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 and n.;4(*ftce-6*chytiss f zaw0 d) fgaits activity was compared with that of a free enzyme in solution. The graph f.s t6h-*)4iaed fz* g cnts0aw(fcy;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 easily denatured. Whi :hqx)6f f-sgvch of the following is the best way to keep enzymes active vgxf-6hfq)s :for a longer period of time?

  Which of the following describes some types of extracell(c n3w dx.*i0k sqsv5pular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in thechbs4j,di- a 9ew5r4f stomach. A study was carried out to determine the effect bhf edsw-r4ja9,54 ci 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 enzyme with incv x tx;hu4u tzp)2;slm.gd2*wreasing 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 reactigl;zxs p*h4; )dt uwuvt x2.2mons. 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 a r) s,x3yqt;s y+ p,qjopj 0s2x91sw zoturnip 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 hom s1ot 3x qwyjs+pzsr);pjx,o90, qs2yogenate 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. Inhiasr9 hk8 x:ildmk w( x*c+mx25bitors to the enzyme HMG- CoA reductase can lower the production ofxc+x l*ris: m2d kw8am(9kx5 h 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 involved in degs 2bre1kda *+naturation?
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 investigatingojy 1ox:b (mr, metabolic reactions in the classroom and were given an experiment which demonstrated ,mr :bj(x1oyo 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 br l ht27xna 8m,oommo q(,)/iof increasing temperature on the efficiency of lactase activity it,o/7qx(m2bi monlh)8rm oa, s tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific sda+zn 45*kbnn8 f:nb lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactosz skb4:an5 fnnnb8d+* e-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 tiyj67::rl8s0j yn p5 afacbk 9z1w2rqo find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with new technologie1 r5bjsqk67 nf9c:laa:0ir j8yy wzp2s.
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 enc+w2 eqw-m/o jdliv :im5+fp/zyme affects the rate of reactio +-p 2oj emqc/mv/ilfd5+wi:wn.
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 metabol;i.7 we kqwe c58q :bczyv)6joic reactions. Which type(s) of metabol.bc6z:y8vw;eck w 5o eqi jq)7ic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differen3+rp s+iikfo7 t ways the rate of enzyme catalyzed reactions can be measur7oifikr3++s p ed.
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 ezzag ojm2yn;* 1*+ nxmm op+d2xtracellular chemical reactions, given one example of az2p*+mn 1j2 ony *;+o zxgdmmeach 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.