Which of the following macron kmrqil-590ymolecules describe a typical enzyme?

  What type of reaction is photosynthesisf8l7h28nt ei k?

  What is the substrate for the enzyme la .zr 5ej an6i3,x3obluctase?

  Which of the following stages of cellular 4 nb2d 9ju4ysirespiration takes place in the cytoplasm? dy44jni 2su9b

  Which of the following would not be useful in determining the rate of an enzyxq/ks1p+ ox o9me-catalyzed reacop1sq/+xxo k9 tion?

  Which of the following processes may be described as c)o/sktz . b-8zmhexg,i-eu z 1atabolism?

  Which of the following statements is bes1caxb;eo9wa1 v.oqa bhrez7ol9 ) j/,t depicted by the figure below?

  Which statement about e670d nom. dimz, uc.venzymes is not true?

  Which of the following graphs best illustrates the relationshi zzcr;c.)1ke up between temperature and the activity of enzymes such;u)k.z1zcrce as lipase?

1.Sketch a graph to show how increasing concentri:6z1aadp oc ,ations of substrate affect enzyme activity1dc ai :6,aozp.
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 dia;/6f/ii7,kaba nb llzgram outlining the Calvin cycl/,i;nb7/ ilfka z6 blae is shown below.

The image below shows the catiym6ggo( 9g3b alytic site of an enzyme. The substrate is shown in black andgb( gg yi3om96 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 descriptions of the enzyme catalysed metabolic pathways shou:*e aw( k hna9hkrh)l p zqwsk)90a80wn below? Letters represent vari w n) 0el 9 kuhhazp(*9aks0wra)q8:hkous products of individual reactions.

  Which of the following describes t1ee.cj eh 89lche role of inhibitors in enzyme-catalysed reaction9jlec1h8ec . es?

  Which of the following correctoqp yle 2;ax)i9gn; w4ly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways inve9tfy5z w qy1* nw5gc3ljj,3oolving multiple steps and multipley*5g,1o lt w59jy jfqncw e33z enzymes.

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

  Which of the following best describes osj cojw6vp(0i+8yslw p7* y 5the inhibitor in the image below?

  Which of the following statements are true regarding regulatiov h4;iqb(cy9r a p8d4wn by end-product inhi8bh w4q49vpdra ic(;y bition?
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 stru 2v1nfkyp3tj7cture of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the active sp7 31knvj fty2ite.

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

The equipment below can be used to stos s.0ck; 6m; h xs.zq;rg9kwuudy the effect of temperature on the activity of thz; u gw;0.xksh;m so .qrck9s6e 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 substra7 jr.lyov*n2g tes ton*jl2oyg r.v 7 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 reactions ca7 ;,:y fmsum ts(r-nain be measured.

  How does denaturation d k)dbrgvppf q 6*c3;-change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which ofm2x*w q n9czv5 the following statements are true5 cz v92xqwn*m?
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 endotherms from ectothcrvg3l (bz io4.ou,7tk4l,l r erms that have fg.7( ro4tr zuv3co,llbil4, kluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-produxm1 6 (owahvfgg,wd2iy 6cy,/w)4 t luct isoleucine consists of five reactiwli4v dygy6h 1tw)ofw( 2,cmax ,6u/gons. Threonine 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 in mmv x rk8m++y5odwp479khys 1creasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the 1p mm9k8yxm ovs 7 4k++rwy5hdgraph?

  An experiment tests the effect of changing substrate concentration on an enzymathm-qumu xd2,. jawy5*0n um i-ic reaction. What could be the independent and dependent v, -u hm uimdw5n2qu-ja*mxy0.ariables in this experiment?

  The diagram shows the pathway that cyf.qj jg gh.ce .5w)d9onverts 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 its activity was compa9g-;sbn daee) red with that of a free enzyme in solutesad 9g-b )n;eion. 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 easily denatured. ajm,n7tw:ubvw gp+ ,wte,5+g Which of the following is the best way to keep enzymes active w t+ev,gp,m7g5nj+t b,aw: uw for a longer period of time?

  Which of the following describes some types of extracellulafh6q k kk 2sa:lzbgn70.p):yor enzymes?

  The enzyme pepsin hydrok7odmx0l+j59fa8ug a c/:li ylyses proteins to release peptides in the stomach. A study was carried out to determine the eff5dg + /8xa kf0lml:j i7uyco9aect 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 increa mx:d ;oj(/0x hz,bc(n zdubr7sing substrate concentration. Similar concentrations of chemicals A, B, C and D were ad,(x7hc0d/rn:bu;b zxjzdo (m ded 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 a turng *vn)afc4wia2t l/x1ip root into small cubes. They mec)wn*g1t lafi/a2v 4xasured 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 beloc- rc9z )to xapiyiyffvmd( 2d,2m,92w. Inhibitors to the enzyme HMG- CoA reductase can lower th2p(2idrcf)y vfm-9d,,o 2t amyci zx9e 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 followioe7cw1 kebml084s 0 5vn2d jmfng 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 metabolic reanc; :3r*: twglk9d09jb yerbx ctions in the classroom and were given an experiment which demonstrated the effect of temperature on a catajxc trln9wy:;bk9rbg0 d* e :3bolic 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, thez(q (w3r frq:r effect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable f:qqz((r r fr3wor this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), anadused(p +trh c* 9e:z8lysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactose-free +eh p9rszt(e:cd8 du*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 continuous5gcr*9-yq,qw *xssq5u e hoz( need to find new drugs for treating patients with malaria. Describe how anti--r 5suoy(hqx*zw,* g95 qcqesmalarial 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 conce;u 71d 7 jdwtozca t*y-qyyq9.ntration of an enzyme affects the rate of reactiottoj; qdwq1y - a *77.cyud9zyn.
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 ssp*e:r1c 7pcrynthesized through metabolic reactions. Which type(s) of metabolic reactions are cond7erpc*ps:1 rc ensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different b wm9 w;-xd e;gvm+1lkways the rate of enzyme catalyzed reactions can be measured. mb-1wedxg9l ;vw m+k;
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 intraceli/2h k :bsfkof1ms 31vlular and extracellular chemical reactions, given one example of eaci:1ms b3h1k2 fso vk/fh 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.