Which of the following macromolecuymo5h c.7wk:eo/ 6nd/ 7tni- xcnq9pules describe a typical enzyme?

  What type of reaction is photosyntzi g:xd mfv v6a*735sbhesis?

  What is the substrate for the enzyme; )hg:zze 73p v+l/wpfok-b nb lactase?

  Which of the following stages of cellularj po ij5/usbxp58o 2toq701 glhzg(n. respiration takes place in the cytoplasm? g( /ljognp pqjo5u.is0 b127x5oht8 z

  Which of the following would not be useful i6pwt p28ehf *dn determining the rate of an enzyme-catadwpt2h f6pe8*lyzed reaction?

  Which of the following processes may be described as catabolismzumf-*kc 5( *gyxk*k z?

  Which of the following statements is best depicted byf+nb)hsw4lnk9, uckd2 69 cgd the figure below?

  Which statement about enzymes is not trucs/yf ph36 xkj9 h-3hd+(ucpce?

  Which of the following graphs best illustrates the relationship betw 6dqc tjq2xcqr +a(2z5een temperature and the activity of enzymes su2j+aq62c 5qdrcz (qtx ch as lipase?

1.Sketch a graph to show how ind8eccpt( a; ,bw.w-k oos; z-jcreasing concentrations of substrate affect enzyme activacop(scbz,t 8;jdk-o ;ww e .-ity.
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 l,npk*rg+qw,s y+lo ) 6ykw3ygram outlining oy3gywp,+ lw+ y l6)rkqn,*skthe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is show /jfew5np3,i zfe:wu/x 24lws n in black and iszwiwuplw 43n5fejfxe,/s :/ 2 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+*vz w.ccoh 3.8znpj hbo8 kd7 of the enzyme catalysed metabolic pathways shown below? Letters rep b. v8*cohj3w dzz8+7cphon.kresent various products of individual reactions.

  Which of the following describes the role of ino(ylkosvnvd61 yb4 g+)8jn3 h0y.f cf7exbn -hibitors in enzyme-catalysed reactionsj+vfb)3hkybe 8dvnl 0n-14fcy y 6o(7 so.gxn?

  Which of the following correctly describes n7 j a0rv5dv i0ec214) nrsoxz4 rm+ulphotosynthesis or respiration?

Many enzymatic reactions happen as pathways involving mul89lpm o0 / /kejaeike+tiple steps and multiple eniemk/ poe/j8e k9a0+lzymes.

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

  Which of the following best describes the inhibitor in th0miq (r/lqgh7zon a6,ia.+ eqe image below?

  Which of the following statements are true regarding regulation by end-prod.n 0uh3n kh n4 -0(edaqyq0qrduct inkrqh. -hu d0q0ay n4de3(n0qn hibition?
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 enzy( zaehd5 lmpwkpo 1st 29-5r.zme. The darkened structure in b5lp zk.we9z atomdh-2 p5r(s1lack 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 study the effect of temperature on the activrc g 7zoxc1efm2,5im +6/ c8jf. qawpyity of the e xf1m epfq 5+gycawr6 ,c.mz27oc 8/jinzyme 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 o/9/odniswr5 q/ fm1s how enzymes interact with substrates to catalyze reactiof dno 51/qosswi r/9m/ns?
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 reactiokepv(6v pdd 47 68gioso p5ecm25rz4ans can be measured.

  How does denaturation change the proed ljfx.:7mht4y : j8lperties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the ); c 067,,ctibvm9vp mdteaydfollowing statements are true?vd6b)c, y 97tcp ,vdm 0eta;mi
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 separate 6s ij1sylm16es mammals or endotherms from ectotherms that have flulyi js61me6s1 ctuating body temperatures?

  A metabolic pathway that converts threozc/)wo.mejgurq.c *ll-m o 62nine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme in the pathway2jq.zloor-)me6.u cg*c m /wl.
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 effeck e6(bt,3o w/fzl i3egtdk 1r)t of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section o kz3ketr/g6w( f3dt, i1l eb)X in the graph?

  An experiment tests the effect of changing substrate co6osdk rg:nx (,* i+ 0y(dqwrosncentration on an enzymatic rea 0+s:rr6dsq,oy*g xn w(oikd(ction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that. y9p f)peiur.a7 ad0b 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 its d +f6uq3 9 ,n(+sakjwzympsooy00r.oactivity was compared with that of a free enzyme in solution. The g90o jfd 6skz0 yw.,+3myu( ron+sp oqaraph 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. Which of the following is the best way brksxy s 8;)ezdq1f21to kr e1 qxd )bzsf;s1y82keep enzymes active for a longer period of time?

  Which of the following describ29,8- ytqtld272lsegp+ tl( zdd twzqes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to rp7:ifizs (;nc kx3p /6cxoy 5xelease peptides in the stomach. A study was carried out to determine the effect of increasing subst:7/cxippn3;x 65csk zyiof( xrate 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 tx f2e,4lz tcas2ja7ha1; n.y of reaction of an enzyme with increasing substrate concentration. S .1yahjx2ft4cn, stza 7l;2eaimilar 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 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 j/n 4wk 9i3l;kt7usgrroot 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. Tt739 uwn4isj/kg;rk l he 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. Inhi5 ts2w7jc8 lnpbitors to the enzyme HMG- CoA reductase can lower the production 8sljtc w27n5p 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 involved in denatur0 djw.qeaq 1k).tl /gbation?
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 aask)-g+bf 7,e1nl fxm0qf4q8;vvek classroom and were given an experiment which demonstrated the effect of temperature onaqf1 b7,eg4vmk0kf8 xsn+);f v-aleq 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 of increasing temperature on the l8jvgv +0c 7njwj6 e0oefficiency of lactase activitwejcjv g76 8jnv0ol+0y is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), anayi6um m7ge5z,cz4zqwni54aeg0)b 5nds d(8x lysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a comm ddq(m7)snx5ei54gzyzi ae4b6gz c ,w0n5 8mu ercial 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 t*p (lw0 bnh(xy0bvf8ro find new drugs for treating patients with malaria. Describe how anti-mala(xp vlhy80f0nbr* b (wrial 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 co f6qd,sp qg40oncentration of an enzyme affects the rate of reactionfs4qo6p ,gqd 0.
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 synthesizeo8gz6kf fkm)6 d through metabolic reactions. Which type(s) of metabolic reacti)of mk6f gz8k6ons are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cat*s eg/)-7h /lrhxjjklalyzed reactions can be measure )-lh7sjx/hk* gje/ rld.
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 i,q5o;xcvt 6a6uj gxj7ntracellular and extracellular chemical reactions, given one example of each type oftcjxuq,6 j;gxvo 5a7 6 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.