Which of the following macromoleculeybkrp2ee8a6qq( b*-5 krk 1ods describe a typical enzyme?

  What type of reaction is photosy3gt 6/bpsc p:qnthesis?

  What is the substrate for thec,x)o(;as j:me spv/z enzyme lactase?

  Which of the following staeb,qpo- r 0-xwges of cellular respiration takes place in the cytoplasm? -ob ,xw-epq0r

  Which of the following would not be usebr147 .ofdyu t0/idw oful in determining the rate of an enzyme-cwd01f . o4drby7oiu/t atalyzed reaction?

  Which of the followingxyj c)ocm/ys,dix-y+c,78in processes may be described as catabolism?

  Which of the following statements is best yhqk)-wol/acv . )i(udepicted by the figure below?

  Which statement about enzymes is not tg1 md))2 h;qgukz nec:c )m,vsrue?

  Which of the following graphs best illustrates the relationship between temperac*igb z(6hk a ,p)yaq9x fdu5o9 b6nv,ture and the activity of pc,6f hkz x, ba vo6ng*qbdi)au95(y9enzymes such as lipase?

1.Sketch a graph to show ho (to:xwac2o n0w increasing concentrations of substrate affect enzyme activity. :2n0octwxa( o
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme cfvx/); o) xb ha -e5ccu+s3xsgatalysed reactions. A diagram outlining the Calvin cycle is shown below. /a) -5ocxe 3 ;+ us)xfsxgcvhb

The image below shows the catalytic site of an enzyme. The substrate is- es38u7jta 8tv/nsds shown in black and is bound to the active sitjtu-ndss7t3 v8 ae/s8e.





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 fka:dc) w5r 4 n8/ghcccatalysed metabolic pathways shown below? Letters represent various products of indivfh rn)w:ag8 c4dc5ck /idual reactions.

  Which of the following describes the role of inhibitors in enzymew4gdtm aff42s5 2gda,ou: i :i-catalysed reactiodu4a2:a2mgdiwsg, f :4 o5i tfns?

  Which of the following corr-1iz,8;cpx3-ms* clu pn :wmxg av5f kectly describes photosynthesis or respiration?

Many enzymatic reactions happen asyf p72oy ;hic9kg8 q+4,lcbl)ktoy d) pathways involving multiple steps and multiple eno)htb gldp ki74+qc,lkycoy8 ; )92yf zymes.

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

  Which of the following best descri0*2in1wq/zih igljl8bes the inhibitor in the image below?

  Which of the following statements are true regarding regulah5g 2vsa)o)rction by end-product inhibita5g)hc rso2v) ion?
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 sowb djxc.x 3yz:j4o6;*mhi+w hows the structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the ac:b i 6.z+x43cjojy wwxmdo h*;tive site.

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

The equipment below 8e 2vsx6uwurpu.1s*x6) em7g1gvqp fcan be used to study the effect of temperature on the activix p 82mgxse*) 1e7uvgurpf16 swuv6q.ty 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 substratesr- gw ezhr7x.f(cl p/u+n4r m2 to catalyze ru7hwpn(f4+zrrr ce.mx g/ l2-eactions?
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 catalysxo**ro 9hbp7r34h rcled reactions can be measured.

  How does denaturation change.zr)4o e7 8i h-mytqox the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which odbd3h/hc;jnvmi 5fnr8 s :+ +lf the following statements are trsfl+/jdcv5m; 8hn3 :hni+ br due?
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 characteriscz;bl i,m s/0agv.(xstic that separates mammals or endotherms from ectotherms that have fluctuating bod0cli./gbs;(v,sxma z y temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine consioq*r/si2eo8* su z5qz sts of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes befois5r qs*8uz 2/e *qzoore 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 an enzymatic regz w3*u,pg.cnmkj rzy/p7p6*action. What is occ* z6ppkg zcu.grp */3y7mwjn, urring during the phase labelled section X in the graph?

  An experiment tests the effect of chau+ pt-)v9nl :jw8gx cenging substrate concentration on an enzymatic reaction. What cwxu:+p vj)nlg9e8 t-could be the independent and dependent variables in this experiment?

  The diagram shows the pa0vjjw)1) fxbbd7 db8ethway 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 its activity was com8glee)jt/9; evii l x9pared with that of a free enzyme in solution. The graph shows the relative enzyme g9)ee8i il9v; jt/e xlactivity (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 besteur 80t0/htncmtnh+, way to keep enzymes active for ,tnrme0tch + /t8nu h0a longer period of time?

  Which of the following describes some types of elam0k j* 5 2zn2pnj;c,cu wp1r 7m5iblxtracellular enzymes?

  The enzyme pepsin hydrolyse4d m+* + c/r/ vxfu+fbjmd(ngbb;ngl.s proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration olux +nf*/ cv+mjm4nrb d;b +gg/(b .dfn 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 enzym rvmrw;/s:nfvr6ad)6g h -3/ bkrqk s8e with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the acti/36s qdb)s6f:k8hv -mw/rnrrvkrga;vity 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 cl::j6bdqp )mf*bi7y dut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogeni6fi pmd )j:b:b7dql*yze 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 pathwwx.f54 e+0 3:mubqkl2( theu owdd/hday is shown below. Inhibitors to the enzyme HMG- CoA reductase can de0l5dow+bh/ 3u2dkt( f4:em xw qh u.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 ilqn hv)457t thnvolved 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 a bay34j5 uz,oreactions in the classroom and were given an experiment which demj 3bzoua4y,a5onstrated 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 of increasing temperature on then ; d6)+- nle:x* sqccjvbnm6v efficiency of lactase activity is tested. Which is an appropriate dependent variable for this ;nsqv*dnlex 6-:c6v) j cb +nmexperiment?

  A study has been conducted on the activity of n2 +n1g14 q8pg utn6xsy1;cuw ypbxr, a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentr,nn;n1 41x t yug2 q+1yb6xppgw 8usrcation, 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 treating patilir.jvr*+yb 1ents with malaria. Describe how anti-malarial drugs arer*jlvyr.i +b 1 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 t1zk 2px u x, g*j)ytmj54dzvo)vcag :+he concentration of an enzyme affects the rate of react:*zgy5j )ojp,vucvdmz+k g1at4x )2 xion.
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 s6f+29hrmxo ayba 1 yj. k0jxa(d22vna ynthesized through metabolic reactions. Which t26hdaam(09ab k21y ory.j njaf2+v xx ype(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed otviq-,f z0kmsg :2( treactions can be measured-gv i:0(t2,mfot z qks.
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+me,+d y9c hsqlular chemical reactions, given one example of em,+d9yqhc s +each 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.