Which of the following macromolecules describe a typi mj24uqj:kkll,1z,g/m xemau(n5m,b cal enzyme?

  What type of reaction is photosyntheseaay:;rk8(co t+*2ib;rf t qsis?

  What is the substrate for the enzyme lacijn7tl;b5 ap 0tase?

  Which of the followikx)e zv4k)g1q+ e z*ywng stages of cellular respiration takes place in the cytoplasmv*4kzkx+q)ye) wz g e1?

  Which of the following would not be useful ina3 /fn6(lqo4mflr1 do determining the rate of an enzyme-catalyzed react4r3 /1(aomd 6 qffnollion?

  Which of the following prd2d4- 0xvmnw9 +xa jzp4n i:7 f(zqunpocesses may be described as catabolism?

  Which of the following statements is best depicted by the figure be2 boef31hwwl*w-j3f nlow?

  Which statement about enzymes is not tmqr.r fzo;6c2: kulc8yd.ot 9rue?

  Which of the following graphs best illustrates the relationship ber elhg9 cx.4tl8 9pgzxi3l*u.tween temperature and the activigxg 99epc4 ll .rth.3* lz8uxity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affpj 5bi:v 6s4fuect enzyme actpbsi: 5vuf6 j4ivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme nd7z7zq6w / pok,2jwm catalysed reactions. A diagram outlining w72kjpd z q now76,z/mthe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is sho,ktty mj(dniger t9+337y ya3wn in 37dy3n(amjgtt +iy,r39ekyt black 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 descritsof5.e,h nw9ptions of the enzyme catalysed metabolic pathways shown e,9wh t5.nofs below? Letters represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed re5z+a( k (nxesfacti f5(ae(xzks+nons?

  Which of the following correctly describes photosynthesis o.jnzut pxr (/u0m8fb )r respiration?

Many enzymatic reactions happen as pathways involvi zpgck(2nvh)wg- fyfh b4g255 ng multiple steps and multiple enzymes. whf-2n4gz) bp kfvg52yh g(c5

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

  Which of the following best describu2w/fcgsda+q7 v )6sy,s 2-qsftqk+ ges the inhibitor in the image below?

  Which of the following statements od7,e7lgwgn 6 are true regarding regulation by end-product inhibitioedgn 7,wg7l 6on?
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 stxbrc1qee6f6z - 3rmrd+ h3lqj ,.g:+x ok pr.zructure of the lysozyme enzyme. The darkened structure izx6 mdj,gr.6elref x-:bz k +cr 3r+ h.q3q1pon black 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 kjl9j--l 8bd:(kyna)9ngrkp/ k/rbm used to study the effect of temperature on the activiarpmdb-k8jnkk 9)bg(j9l k//lnr: -y 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 substr wd:b xibe(8/gjj a,-dma7 n x*3qhua;ates to cadnbxhx*be8 ;miqgu3d,a:a 7( w-ja j/talyze 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 enzyme catalysed reactions can i7 q77qf(tk+rq yy ,lkbe measured.

  How does denaturation change the propert t*lv ,m)8p8-ge/f ja kcv)l:e9yo) (gbkblx kies of an enzyme?

  Enzymes play a role in catal 12 30gcveaqgaysing reactions. Which of the following statements are t0ega 1cg 2vaq3rue?
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 6upxfcp c97 .a)ee+yo 9a-iu oendotherms from ectotherms that have fluctuating body temperatures?.)x i puuep e 9-9yc+ca7oaof6

  A metabolic pathway that consw2pjl,+,w s tverts threonine 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 pathway.wspw s+,l ,t2j
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 effecm /ovr xj66s*ht of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labh *mvjr os/6x6elled section X in the graph?

  An experiment tests the effect of changing sy(7 (gc6 2ywtk5kfc/prm q;a pg7a.o substrate concentration on an enzymatic reaction. What could be the independent and dependent q . ayg2(pck6yrmstgpk;5/ 7(o caw7fvariables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucine.cvl itlsv5s:)2d2nv 3



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

  Enzyme A (Enz A) was immobtba5fs5 64h beilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph s h4bs b6fte55ahows 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 denatu xwdbd .uk4)o2red. Which of the following is the best way to keep enzymes active for a longerx)ub2 ddwk4. o period of time?

  Which of the following describes some types d.l :.*po0blvxuvt a(of extracellular enzymes?

  The enzyme pepsin hydrolyjv tuida*3 d0i+m:w-d ses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme actividm3ta0v+-:idu jw *dity 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 r e,iv;/8q rmyjx7h)bl eaction 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 the reactions. The curvv;8j/ yl em)i,r 7bhxqe 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;(msrcxeh m0n7 uhd8 e l.t1k1c1gw /l cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The hom; 0llctc1xd17.1( hermk8sne/ ghmu wogenate 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. Inh y8ch3leg7dsv5 a86 xtibitors to the enzyme HMG- CoA reductase y8ev7 sc 56lt hd8gx3acan 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 ar*2w mbo :m6dcxe 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 investigatd/ mp .b+v(mc.c0xutdos )7l qing metabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reacti0).s cpbdtcv xu(m7+d/.mlo q on.
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(p rhb ,4,a0ev(ogg pf of increasing temperature on the efficiency of lactase activity i o(pgg(,rp,bfha 4e0 vs tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analysiq wi;2-1g dkujng the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to quig;j 12dwk-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 .+75 n5.s:zi*usgceq vnpodkfind new drugs for treating patients with malaria:.zodvsekc. 5 *+np7s gnqi5 u. Describe 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 conet ja9;kib *5p2vib0,nva vgi7,z qs -centration of an enzyme affects the rate of reac7 -is5ve q9ki,;j av a2,*igzbb0ptvntion.
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 do: lx( wruiz/7ewn or synthesized through metabolic reactions. Whichxlrz 7wi/u :e( type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed react9lbm.s pwl3ut bm 6dsm1 r 7/8 ce.hq5nnb)1qcions can be measurd8nnblc.rlqu7t59mq b.psb 6m 3w/ s he)cm11 ed.
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 extk:z8mila+ d x7racellular chemical reactions, given one examplel kai7 8+dzx:m of 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.