Which of the following macromolecules describe a typical enzy gxhojl *3,l tt,-(;ixgono/+ )wncx wme?

  What type of reaction is 2jvc0ft w6-md;a(n9y rmun,u photosynthesis?

  What is the substrate for the enzyme lactase? i*(pra/tkhdb 8-bmo 4

  Which of the following staght-d)ul: z mvyw9,tq 7es of cellular respiration takes place in the cytoplatq mh9 z:ywu7,-vt)ldsm?

  Which of the following would not be useful in determini im97 8rx(* + c.fzk/juxbhtadng the rate of an enzyme-catalyzed reabi.xf a97(jzkdurt/+cm8 * xhction?

  Which of the following processes may be dba 8g1+us8vwj *axw8sq9n7tn zm w 47fescribed as catabolism?

  Which of the following statements is best depicte2 n:v mkua;;b3kadn7u4nkhug(9 0p ysd by the figure below?

  Which statement about enzyme,3u x,a0 wnzf d0-d sdme5zq+ws is not true?

  Which of the following graphs best illustrates the relationship between tem:x)snfbj fl 61z2pd9s f1 b,luperature and the activity of enzymes such fss2zjf ,dul :6b91l1 xbpn f)as lipase?

1.Sketch a graph to show how increasing concentratiow;utwyalj: n1 1rl-kbdcl* 9.ns of substrate affect enzyme9d:;-.1 r u*ljb1klwnywca t l 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 react3uqd 3dfac4j0 ions. A diagram outlining the Calvinu3 ddcq34j0 fa cycle is shown below.

The image below shows the catalytic site of an enzyme.oknltu9he u/ z vt*3/8hd(g:g The substrate is shown in blackto93 (/n h/zuv* dthl8gu:k ge and 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 (c *fovh p-9(o1 ysexxcatalysed metabolic pathways shown below? Letters represent variou1oo-ch x *( v(yxs9efps products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed re1s9 hoym*t l1 (gjh psm:z93fgactios19*mfh g9(3y1o mgshlzj :ptns?

  Which of the following correctly describeso3w3dybkq 3id+z( yp( photosynthesis or respiration?

Many enzymatic reactioj7z gi17v/ftlt6i8(lr6igid u+ t 3epns happen as pathways involving multiple steps and multiple e1lie6j6/ tzrt+pu83dv igli7f7git (nzymes.

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

  Which of the following best describe;u( +56trqc(j kyylw 93dtk vqs the inhibitor in the image below?

  Which of the following statementsaadc jp2 134o oqnws13 are true regarding regulation by end-product inhibitic3d4an awoo3 psjq21 1on?
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 en zwt+fq u iuzyc+:g +*/3s3tqzzyme. The darkened structure in blackg usz+/zfqz3 ttu+: yiqcw+3* 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 effect8k7 d lygg-v.x7m o;vp of temperature on the activido l vk;7gy.m8v 7g-pxty 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 sta j7uaw4d i r-x6d.tu-ftements describes how enzymes interact with substrates to catalj764.ixdwtd-u -u frayze 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 enzy.bgk+ibnb z;l1zpgx .6sa)b9 me catalysed reactions can be measured.

  How does denaturatiok z-)l,cd/zu nn change the properties of an enzyme?

  Enzymes play a role in cata2oi2,3yhj mhhyc,fvbz(5 q5 alysing reactions. Which of the following statements are trcm3 vf2,, j2 yqboy5 ziha(h5hue?
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 endothermshrov 8ed34//p8 qcshic.po2 v wom(i2 from ectotherms that/vr/vqp8deh c2 2ci3i4 h8op oms( .wo have fluctuating body temperatures?

  A metabolic pathway that convbxoeyv j:3(mu w 44qsdi0(a5werts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to v byeq( a:(wdmv3x4 ous45i 0jwarious 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 increa2a .rzuyqe5b3 )pz yk5sing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the gzea urz5q ) y.32ypkb5raph?

  An experiment tests the effect of changing substrate concentratibs /8el lj ky(m2fz;z5on on an enzymatic reaction. What could be the independent and / zjkz;m5l8l(ef2bys dependent variables in this experiment?

  The diagram shows the pathway tpd bmdad vurw xxo6k-/*)ots 3v62 7/ jwnh/b4hat 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 activity wasuld: ccw*(k7awj o6 ktfj5:c5 compared with that of a free enzyme in solution. The graph shows the relative enzyme alao:( 75cd5wcf*uk:j wjc 6tkctivity (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 w8u,0ln,.iu dv7 qnaik ay to keep enzymes active forluqu70nvai,, .idnk 8 a longer period of time?

  Which of the following descriyb,0 lr89w ys )rela55b x1bxabes some types of extracellular enzymes?

  The enzyme pepsin hydq dt(* li3uv7()q) hjduiw) ltrolyses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing l(it it*3q l))djw) duhuq7 (vsubstrate 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 wivtmgbp70rex0kt . )yigk(88i th increasing substrate conc8y b 0(t. )x 7kgvitmp8r0iegkentration. 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 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 int.b8kyy 8yw 0reet .-s/py 7dyoo 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 dy.-/ty0opke.be rys8 7ywy 8 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 sw*mi 9)- 0xhn shaaz5 en mz5 og2rdy7ru,9n1vhown below. Inhibitors to the enzyme HMG- CoA reductase can lower the productiong*hov1)9mim 75naew -r5d a ns rnxyz 0h9,uz2 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 de xrdn54y5 p0*jakzj .4 wna4ugnaturation?
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 wer 8* x91rxzpk7l rq)s1za(vf jxe given an experiment which demonstrated the effect of par1 8)1qxx*s7 zjrv k9f(xlztemperature 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 of incre(pr(vzory.c)(eef yhb0 )t)b uw dr46asing temperature on the efficiency of lactase activity is tested. Which ert)dcrfe0ryhw) z. u)(4((pov6bb yis an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specifiz8 qi+ jg6x1qqc lactase (Bg10), analysing the effect of pH, tempe8ijg6q 1z+ qqxrature and glucose concentration, as it may 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 treating0zpc9 riz) n4i3(y sry patients with malaria. Describe how anti-malarial drugs are being discovered with new technologiirc0(3ns4)p 9 zi yzryes.
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 eng2v7j ur 3fxbyc ;q)6-mk6xq 1)enut izyme affects the rate of reactiqxg)xqt 3)f2n6r -ey bcuuj;k vm617ion.
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 brok 0 7zwh.sjq.b1cs rzv5en down or synthesized through metabolic reactions. Which type(s)7 c.z0 1bhqjrzw.v5 ss of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differexn159p9evkv. 7iovs ant ways the rate of enzyme catalyzed reactions can be measuresa n5e kvx9vo19.i 7vpd.
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 extracel ) plhrqg+dksy g5z1*.lular chemical reactions, given one example of ea gkr y*g5)1d phql.s+zch 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.