Which of the following macromolecules describe alk6/iwm +bdm ; typical enzyme?

  What type of reaction is photosynthesis5 o2 zk) li3q58ywxtb/d/fwhj?

  What is the substrate for thev17 ekpt0q1ogjov al5i 9n ,4b enzyme lactase?

  Which of the following stages of cellu 8d)bwa( vg7whlar respiration takes place in the cytoplasm? gwdvw bah78) (

  Which of the following bkpl)s z ;5-wzwould not be useful in determining the rate of an enzyme-catalyzed reacwp l5k;s)b-z ztion?

  Which of the following proce0 *g qkvk jl/i1mm8cy/sses may be described as catabolism?

  Which of the following statements is best ryz*3s9jr4r tdepicted by the figure below?

  Which statement about en roak c1wo9yn) + x1p1dd+5wjzzymes is not true?

  Which of the following graphs best illustrates the relationship between tn ag.6k koeykbnq+uy3*t-h 87 emperature and the activity of enzymes such *8anhu.b6kk eny+7y-q 3tok gas lipase?

1.Sketch a graph to show how increasing concentrations of substrath defq+a; p(-c:px o8we affect enzyme acticwh eoqa:dx 8p -p(+;fvity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series oqvlc y6*qc 1: jqpxuiohjr n*1;d 912pf enzyme catalysed reactions. A diagram outlining the Calvin cycle is showjqn*q ccpo9* ;12uyd6:v 1jlx 1q hiprn below.

The image below shows the catalytic site of an enzyme. The substrate is 6g dt9p; wb erdbo.+,kshown in black and is bound to the ad,kwb t;+eo6. pbg9r dctive 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 metaboli uxi)+m v ncqa nv3myjluuv(f.)245-dc pathways shown below? Letters represent various products of individual rufu 53nviv njmum4)v(cxy+d) aq.l-2eactions.

  Which of the followinyn2s0loerbj qd,: oi/30z wx2g describes the role of inhibitors in enzyme-catalysed reactioob0dq/i ,szwlo022 y rj :n3exns?

  Which of the following correctly describes phbcw 17cqjle i ay3l5k 75*h2au;zrrs; otosynthesis or respiration?

Many enzymatic react6 sfn w(bg:l9 r(vg7huions happen as pathways involving multiple steps and multiple enzymeslgb9( 6: ng f(s7ruhvw.

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

  Which of the following best describes the inhibid hlj z(za:azy6hi+-ly .s,d2 tor in the image below?

  Which of the followi ypak g90uc9r(4jo 0cvng statements are true regarding regulation by end-product inhipkj4y0 c0 9(c9varg oubition?
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 enzymem3 yp;+hb ;jatp --2h+ul(oj hl vs)dx. The darkened structure in black is the substrate and is boundyt(auosp ;hjx-l2)dj+b+v hpl ; h3m- at the active site.

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

The equipment below can be used to stud c/w2md /er4ury the effect of temperature on the activity of the enzyrc r m/du24ew/me 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 enzoy+ og,qzf +s4ymes interact with substrates to catalyze reacf og4y+zoqs+ ,tions?
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 reactions can be mg:/e - zypbmxv0w)7e4ujs zc3: (ic:yq0qv vgeasured.

  How does denaturation ch ;k;dubbr7p v)ange the properties of an enzyme?

  Enzymes play a role in catalysin-ro;5uky k dgf ve44cknk0;2jg reactions. Which of the following statements ak4unjok5k-g0vrf ;k4c ;e2dy re 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 f1 ou9bzn:iwwo n5k4 fci3 lx6(rom ectotherms that have fluctuating zni4bx16fnkw:3o(lio u 5w9c body temperatures?

  A metabolic pathway that converts threonine b a6vfnn-g1 jk,:3ca qbbp .d*to the end-product isoleucine consists of five reactions. Threonine is converted to various interp.1 v,*d3bb-an :kf 6nbqcjgamediate 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 increasing pH on thd+8 smh9f3 yo w 3loh:/ 3(svgbcze5kxe rate of an enzymatic reaction. What is occurring during the phase labmb(z es93w h53:os3 ygvxdo l/+h8kcf elled section X in the graph?

  An experiment tests the effec8kout;d-8 n9 xgw)zrsgecj22 t of changing substrate concentration on an enzymatic rs ek-ug t 288nz9c2;w djogx)reaction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isodxt ydv9r lms: dc,ti 9+r09g6leucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobi272tny4:ti9mkby je xlized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying tj:xb2mey47 t2 n yik9pH (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 w(4 et6j:ez b;xtb no/cgkcx mx ,,cr5*ay to keep enzymes active for a longe4cj5;e:b,*6 (kbx g,x tn ce/m ozxrtcr period of time?

  Which of the following describes some types of extracelluleqkwoq1aw-8;m. m/ p ,d xb6ffr-okl7ar enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomac(ds oc o (dg-;x.cxa)tgikc3vxf)c 1+h. A study was carried out to determine the effect of increasing substratv isgc3o.c)+x-;kcx()dc gxa( tdo1f e 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 with increasing su; la;.s9m ectpbstrate concentration. 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 acti;.lcae tsm9;p vity of the enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyor)nts40 *f vmy5k1p nme activity, a student cut a turnip root into small cubes. They measured approximatenr5)f01o ptm*n4v syk ly 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 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. Inhibitors to ty0x7uh+ov6q zd j y8n ;h9ilx.:7 g xxv)iojc0he enzyme HMG- CoA reductase) uoq hj0zxxy:xi.jivo; g +v 798ynh076dx lc can 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 involvedtpvwq 0jdjlo4 4d/ h7/ 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 investigan);i e tp0f6sb1 tb+eqting metabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a ca)ntb ipsb 1e+06; etqftabolic 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 i4zr guo /km6dzw,l.1/yswr( sncreasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent varizl ,(1msds4 wo6r/ zukgr/wy.able for this experiment?

  A study has been conducted on the activity og9ei5 uez u q9,+6cquqf a specific lactase (Bg10), analysing the effeccu z96u+ie,qe5 guqq9t of pH, temperature 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 continuov7jnzo0zw1 k nu p:(;yus need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discou k:(z70n;yvo nz1wpjvered 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 wi3 * fw ;y;s0vzfbh(fconcentration of an enzyme affects the rate of reaction.0ffwif3hw*( bzy ; ;sv
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 h5i dpt:j)w)t metabolic reactions. Which type(s) of metabolic reactions are condensationht) :t diw5p)j reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different w)ckj hi)ppx 7:kbn9q+ tl+7 wlb)z6yaays the rate of enzyme catalyzed reactions can be measu7l7y)b q9x6 tcp:kw ilh+ak)+j) zb pnred.
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 extracellular chfu7qegc4;rb, ppsp1+ emical reactions, given one example of each type of pe pscg,u 7 1b4+r;qpfreaction.
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.