Which of the following macromolecules describe a typical enf40 ycnhpb(+ j6:fprzzyme?

  What type of reaction is f- g4o lmy(/hj6 2c;upbja1ww photosynthesis?

  What is the substrate45 3wwuhj )lh2; aprxo for the enzyme lactase?

  Which of the following stages of cellular respiration takes place ezux1 w+dxj9) in the cytoplasm9xju1z)xw d+ e?

  Which of the following would not be useful in determinl ,queg5f-5: awi qd8hing the rate of an enzyme-catalyzed reaqiw,ad5 8lefgqu :5-h ction?

  Which of the following processes may be + k( ;hggotje/described as catabolism?

  Which of the following std(5(mjul dx0w+u:h on0cp v+ratements is best depicted by the figure below?

  Which statement about enzymeh/qkw6fbicb 20/a 3pa ers*xs1 (o1vcs is not true?

  Which of the following graphs best illustrates the dngmcxj(*d h**u) ,/wfgp2uyc 7p ww5relationship between temperature and the activ c5up7ywguw* hd*dj ( 2 fx)pmgn*cw/,ity of enzymes such as lipase?

1.Sketch a graph to show how increim dm;7t.4tu easing concentrations of substrate affect enzyme activitm 4itd ;mu7t.ey.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyglow0uqol f. 8ie;8s1me catalysed reactions. A diagram outlining the Calvin cycle is shownlwgqo8 s8u0e1f.oi l; below.

The image below shows the cat 4vr *;n 0wfquq(oeom:alytic site of an enzyme. The substrate is shown in black and ner(v qm;u 4oq*wo:0f 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 enzgk;4anbbpm: r(o- *onyme catalysed metabolic pathways shown below? Letters :4boap b-*n orn m(;kgrepresent various products of individual reactions.

  Which of the following describes the role q0n +y+n2tldr, bgz2aof inhibitors in enzyme-catalysed reactions?+tbal n+n,zyr d2q 2g0

  Which of the following correctly describes photosynthesis or rerr/ vdi f(nb95mse3 d7spiration?

Many enzymatic reactions happen as pathways involving multipofkmtd,:if n,x cis-:l(-o4ble steps and multiple k(l:td4c -ixbfs-mo,,oi: fn enzymes.

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

  Which of the following best describes the inha)yn8naan+1x qn9- x+n,xq xjibitor in the image below?

  Which of the following statements are true regarding 79b abtwwu68hlvll(-; kia 1c regulation by end-product inhibitioc kl9aulbi;a 8-hb7 w (v6wt1ln?
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:6c-zam,mr7f qqbk6q the structure of the lysozyme enzyme. The darkened structure in black is the substratcz 7 qaqmr,66-fbqk:m e 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 sab+)x 0lei)f78 dwsdt tudy the effect of temperature on the activity of the enzyme dlw ) xad8)f0i stb+7eamylase.



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 describesykiy 8f)jcrs( a.* yp: how enzymes interact with substrates to catalyze reactions? iy.*j s8yykcf(: apr )
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 enzymeb9fwb j5a*m2 b catalysed reactions can be measured.

  How does denaturatio3e 9e9gx qd6vbn change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the f ln(x(wz swz/u(a v9cb 2p-na7it0p8dollowing statements are in0az w(98p vub s/d7a-((pn2zwlcxt 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 endotherms from ect3 jw-otvu04qn otherms that have fluctuating body tempet n4o0w3-qv ujratures?

  A metabolic pathway that c:o5w:u-dnk xy onverts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermeu: yk5:nwox- ddiate 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 increakb5fcc3 .lo/67eg9lvs ws8ht sing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section kw 8fsg3 /ebtcvs67cl5ol h9.X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzyhfoe0ky+r9lm zcv ,+ 6matic reactiov9l6 m+ky,c+0 heozrf n. What could be the independent and dependent variables in this experiment?

  The diagram shows the pat 1joxw+p c8 e0ofcy+;+u)td uwhway 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 os zl 5 vo:mrue9k6r,k1n a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the re: evsz lomr9k5r 16uk,lative 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. Which of the following is the best wa uj .b2twsymi/p2 k tzq-d9;6qy to keep enzymes active for a longer periu/dtj 6- yq9tz smpw2 .2k;iqbod of time?

  Which of the following describes somg8c i5d ;1lx 5*h;axkws5 fz2ec4gwyhe types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release xzo ae5hi +mqn9hxcn eg5xbs2:/37i 0peptides in the stomach. A study was carried out to determine the effect of increasing s07 h gesqx9bn55 e c3xz/: anhxiiom2+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 re 7ra51lr2a9rbqoxcjp 9 y(yd) action of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C andla) (jo979arqc rydp12 r5xby D were 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 a turnip root into b5ug3o9k-d,yjz 7fujfo 7rhd0 y(u u/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 extract was stored in a test tube at rou-jzob75ujyddr39f(k ofyu 7/ 0uh,gom 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 ez davv(, q9:udnzyme HMG- CoA reductase can vd(avq d:z,u9 lower the 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 following are involvk9jpc kz, v0o:k4f h06hdrz)c0itul 6ed 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 were given sog-oau 5+x2up 7w k*z q,jr*bz.yl;van experiment which demonstrated the effect of temperature on a catabolic reac+vw7;-lx *zzgak,*5 u ps juy 2bqr.ootion.
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 m: 7at:rx dy fyg2*ddgl.yo3.on the efficiency of lactase activity is tested. Which is an appropriate dyagxfo ddr2 l.d.ty 7m:g:*y3 ependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase bn8 ;w(.6*tz6izpyw)f ufzx zx/ jhz+(Bg10), analysing the effect of pH, temperature and glucose concentration, as it may yuj(fzz8 nwi6;b.)hz xzt+* p6z/fxwpotentially 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 continuoui;q07 4czyprxoa 0zf;s need to find new drugs for treating patients with malaria. Describc4;i rxzafzy o;q070p e how anti-malarial 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 concentratizdu9 83 x bmyh(ema:6xbyqf15on of an enzyme affects the rate of reactam uxh3e5(yzxb:8b qym69f1dion.
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 metab e.rod/trp3g z,o83a iolic reactions. Which type(s) of metabolic rep .oo r/agdz r,t33i8eactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactionvr c0hkni12 hqi-s -n:s can be measured.k 0-2hsn:v1hq c ii-rn
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 contrastnvx.;j( pj l)f,w:yys intracellular and extracellular chemical reactions, given one example of each type of reaction p;wj)x (s:njyylf. ,v.
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.