Which of the followinlc62uyk od-xcsu2 ty4i* e(x1g macromolecules describe a typical enzyme?

  What type of reaction is ;4hg6(zi)v/d2p+u m zm.dk-alebo jr j9de.kphotosynthesis?

  What is the substrate for the enzyme lactase?+ te:wr pb*:m ;oay5ln

  Which of the following stages of cellulaq blb.-p;*fh54itdx j r respiration takes place in the cytoplajp5*tq 4ihl b;.- xdbfsm?

  Which of the following would not be useful in determikf;k)(y- 7jvfk /s fpbning the rate of an enzyme-sf kv7;y kjfp/)bkf( -catalyzed reaction?

  Which of the following processes may be described as c(m :l(ga4)a5z zy+, 5o4xtay+hw uspvq qc7rsatabolism?

  Which of the following statements h bcy; p1c (vc+2ia4jknencv9,33h eyis best depicted by the figure below?

  Which statement about enz 1w8h;for n9uj(dv6hyymes is not true?

  Which of the following graphs best illustrates the relat nhx+9o,fq/w.c zt9 vhionship between temperature and the activity of enzymes such as lipasezfw.o x9/qv 9tc+h h,n?

1.Sketch a graph to show how 4c-uksfnya 4wr 3pj-p)xzc yz-z:);cincreasing concentrations of substrate affect enzyme aa;c):s -zyzjf nzc y-p344-w pxurc k)ctivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed react7 keuj/ /jvs0zow1d;x *pacq 2ions. A diagram outlining the Calvin cyc*0e z wj2/xud/ a k;jpv7qo1csle is shown below.

The image below shows the catalytic site of an s-e )vldxjzw8 rz/ t.8enzyme. The substrate is shown in black and is bound to the active w8. /8rz eszvl)-tdjx 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 pathwaa m+vx71y6e hsys shown below? Letters represent various produy+avs67 h mx1ects of individual reactions.

  Which of the following describes the role of inhibitorsw;zwcjldjj :;w yb c-w/:of52 in enzyme-catalysed reac-wwc2/: ljcd5:zj;wbo wj yf; tions?

  Which of the following correctly describ (pwj77z:p ou e t,+dlo-a+mcyes photosynthesis or respiration?

Many enzymatic reactions happen as pathways invo9csvry sbf:+l*1z v,4i . xrohr1x *cjlving multiple steps and multiple enzym r*xib rv9sfzy1x:h.sc1lc j *o4r,+ves.

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

  Which of the following best descri0 f88a+thjco)ujdn 1gff nv.+bes the inhibitor in the image below?

  Which of the following statements are true rega/sw-6r df.jl rd6jgvj4 :b d7brding regulation by end-product inhibbjr6: dlf7r .g4d6wsj /j-vd 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 structure of the lysozyme enzyme. The darkene iib90fn-pnonb gt*5pzmv27erabc16t h/t2 2d structure in black is the substrate and is bound at the active si2v p7tf/bo-nm205pt ra2 1nz6b* gi9tinbceh te.

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

The equipment below can be used to study the effect of temperature on tlgk5+n6 ugw/urt lq64, donwa2y;5adhe activity of the enzyme amyy,ku/aqdl4a6 lw+w 5tg n;g 2nr 5do6ulase.



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 hi9htn cs f6d2hi* 9bqe 39zg2now enzymes interact with substrates to catalyze reactionsh*f b nin zch326 tdeg92i9s9q?
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 reaceyvu-c , ur72zbktwu +b71:xp tions can be measured.

  How does denaturation ck co7 -)w4 9dulnnox4*q 3vt7okx 4szghange the properties of an enzyme?

  Enzymes play a role mwsp2 v/0e, v r82zovoin catalysing reactions. Which of the following statements are tw pr08voz sm/2, ve2ovrue?
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 sepanb0m4 5ocg0f3 k:j wifrates mammals or endotherms from ectotherms that have fluctuating body temperaturei4:mbo gw00 fjn5fc3 ks?

  A metabolic pathway that converts threonine to the end-product isoleucine c)-phg lxm+r+ xp v*z51gwfq+fonsists of five reactions. Threonine is converted to+* pv q+ r+mf5)gzgl 1hxfwpx- 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 increasin2w5i(uk/, c)urc ug+ xdy e.l+r:g wzpg pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section Xy /+u2rgc cwur:pwi .d(,+5 zgexl k)u in the graph?

  An experiment tests the effect of changing subsdb . (be-o89m2a cdftftrate concentration on an enzymatic reaction. What could be the independent and c8bdm2f(a. f-e b do9tdependent variables in this experiment?

  The diagram shows the pathwry s-/8zw zhjvt *)t*eay 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 activityhc* qoo. t.re+ was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH.rcot *.hoe+q (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 folloalkty9 tbs(nj:,mfbo3* e j ml5s252uwing is the best way to keep enzymesfojb , tl5mk2*ajn2t:leu m(3b 5 9yss active for a longer period of time?

  Which of the following descr.n o:v4hm3c8 l0d gciuibes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses l:( fnh/hvlp* proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concen:(llv fph*h/ntration 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.rkzg( wr tbfknvu+g3i()75 c rate of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monitored for each of )wkbg 3(ziuv +frk .c(t7 rng5the 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 small cu3sfxh 4.nw un146 6 mm(uqz6syqfue b(oj-5pabes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The hompy65 bm mo-nnzjsuq( 4whfq xs3.f(a664u1eu ogenate 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 sdg a8gb /kz.ukhoc/df+/*uf 8hown below. Inhibitors to the enzyme HMG- CoA reductase can lower the +g8*guuho/dc /.bka8kff/ zd 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 followi/k4132agaz kmldz9 qqng 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 rtzz y 5e.wuiq/ d-*v6jeactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reaction. vw y*jzud6/qit.e- 5z
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 xy2x o;a xux ,:t akc/0-xj-lkincreasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable fork;xxkjx :0 /o,-aytxacu2l -x this experiment?

  A study has been conducted on the atfq kso2 f6bkb( k..8dctivity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produ. q6fkdbfsk 8t b.2o(kce 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 patients with ma/ee sim06v o1ilaria. Descr0v 6ie/s 1moeiibe 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 concentration of an enzyme affects the rate of reai 1.lypw1 y7sdctio11yis7 wdy.l pn.
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 metabolic m sdm 66(xa+(qn1oj1 q sf)raxhg9u/ereactions. Which type(s) of metabolic reactions(sx6+ )qr/ 6 9os1ahengmu1mfqjxd a( are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the ria)jom;f2g6k ate of enzyme catalyzed reactions can be measureda2;6fji gm) ko.
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 intracellulf qf.t f/asbdc:u 2+*ear and extracellular chemical reactions, given one example of each type of reactionc+f2.fdtu:f eb*/sa q .
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.