Which of the following macromolecules:ia5,c mbn2ae describe a typical enzyme?

  What type of reactioqnl 1gzvb r/48n is photosynthesis?

  What is the substrate fo-g(mn hbcb-nv zfe)z;ycg /y 49i 8:oo1 (pajur the enzyme lactase?

  Which of the following stages of cellular respira.6d*/b 7unzq j xgkr/dtion takes place in the cytoplasm?6 ud*dzxkjgq/7rnb/.

  Which of the following would not be useful in determining the rate of an enzl,v:* fsl:g mgc.2tfvyme-catalyzed reac2vlg fl, fmvc: :t.s*gtion?

  Which of the following processes may bkb82 6zm;y(8j e+xiwvfv 4mice described as catabolism?

  Which of the following statements is best depicted by the figur i/g bgu*y6h2z t;hug4 h2(biye below?

  Which statement about eo,)f 4f0o6pustnmaac- / l-e(* yzq dvnzymes is not true?

  Which of the following graphs best illustrates the relatiha5 pux q(7sg2onship between temperature and the activity of enzym axg 572(uphqses such as lipase?

1.Sketch a graph to show how increasing cox1mmikzmal m*7p49g ,wa xx 68ncentrations of substrate affect enzyme actz6ma14 kgxxa,8 lm px*m 9mw7iivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series : ovfx9s*4sg3kln 4fmof enzyme catalysed reactions. A diagram outlining the Calvif4fv9om*x3k: ngl4 ss n cycle is shown below.

The image below shows the catalytic site of an enzymfpd : wb0lc26re. The substrate is shown in black and is bound to the active sibp :rwl 206dfcte.





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 desc2agb9 dc drhf4*p4 a+priptions of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individual re+*d2 gf hp4 9rpbdaa4cactions.

  Which of the following describa. 1fu 8b4knw8qr5t+; mvua obes the role of inhibitors in enzyme-catalysed reactik.8w51;q+ ubov8 taaun f4r mbons?

  Which of the following correctly des zhx;1u,hf +nycribes photosynthesis or respiration?

Many enzymatic reactions happen as pathwa5n wofhno-0*dhwx1 5tys involving multiple steps and multiple enzymes. w1hot nw x-50 5fnd*ho

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

  Which of the following/qv)hn6myd*u pc07wo1nt 1cg best describes the inhibitor in the image below?

  Which of the following statements are true regarding regulation by end-proybt,u9k a ucy/mhb4e61;j+xox wr e++duct inhibitio y6x;kc mw+,brx 9+etuoy/4 h1beuj+a n?
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 lqop m(4g*k;oof the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the active s(om klg;o4q p*ite.

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

The equipment below cqfs3ba9 vh d0-xjr6v2an be used to study the effect of temperature on the activity of t2 sfr d- qh96xva30vbjhe 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 statemen +-a: xmy ,-nxiueds:bts describes how enzymes interact with substrates to cab-i+ n:y ,:m-eadusxxtalyze 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 reactions83pyy( vof p7: mdzu+r can be measured.

  How does denaturation change the pb5 :,--s3m;ci eiqc m,nzw gkyroperties of an enzyme?

  Enzymes play a role in catalysing r6+ lwvea)hj y5eactions. Which of the following statements are trj+5 ave) hwly6ue?
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 endot- 8ialpnw c h2n.p8:yoherms from ectotherms that have f8 y.po pc2a wnh8lni:-luctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucp4pvq yp*+ m1nuk6 e9z ebs-)nine consists of five reactions. Threonine is converted to various interme419m zespnvyue)q* np-b6kp +diate 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 incnw:. s(o/1 od3nycmkt reasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the grapo/(1ynt3wm os.kn dc:h?

  An experiment tests the effect of changing substrate concentration op5n9 i,0ilaiwlo+ )n i,/coaln an enzymatic reaction. What could be the independent and dependentc5il,o w0ni o)llii+/n,pa a9 variables in this experiment?

  The diagram shows the pat 0c aebrf)r mfq;8x *0pdki*a2hway 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 wask2yld/,aas wtqfgx 75u/,d w* compared with that of a free enzyme in solution. Thw dq*w/y/ld,2kagx t 7af5,use graph shows 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 denatured. Which of the following is the best way sg7qa hf4 ch31to keep enzymes active for a lonh 4fq3 scha7g1ger period of time?

  Which of the following descrj (limhmv:(w o(o9uw7h av8nvva3 yp9pz*d 60 ibes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins th(kay4 mf -yd2oz0 uj3o release peptides in the stomach. A study was carried out to determine the effect of increasing-kaho3yd0 42fj zm( yu substrate 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 enzym: kfc-p e(t4,f lh,yzge 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 curve marked peg, kf ,t zf4l-:hyc(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 enzym3*b) 84u 8u1 fshjwmzfhki-fde7*azae activity, a student cut a turnip root into 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 wzw* ahzsib f1fu 7uda4kfj-)3h* 8me8as 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 the enzyme HMG- Co0p31:dt bjt24ab leiu96vg t eA reductase can lower the production of cholesterot2agde j9 36t b0ut1evipl4:bl.


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 denatuzm(w w9p7/9 7ft7sykk6hpr i qration?
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 classc qm-0cj f9.7 h)oo3li- +bjoj3*txj omt(lzhroom and were given an experiment which demonstrated the effect of te9c 0 qjlh(oc zmtl)-objj*tx3-o 7fim +j3oh .mperature 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 ex oh3b s5*)ndkps fc/.ffect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this experime.3c sxskbn )ofhp5/d*nt?

  A study has been conducted on the activity of a specific l5gcqo 3+kxu1 v/oz 1izactase (Bg10), analysing the effect of pH,vzgi q1o5oz3 c/ukx1+ 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 continuous need to find new drugs forv3qh7l28sgdo . sww8p treating patients with malaria. Describe how anti-malarial drugs are being discoveh owvp87w2 ld.s8qs 3gred 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 4x a3- 79 x4uomk4 y4ut/m1zu-jrvgym(ilecpthe concentration of an enzyme affects the rate of reactionvux3(7 -ux yy9p4rgi lzeajcm m-ut4/4 1ko4m.
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 metab;4i kymo1c5k79j tyo molic reactions. Which type(s) of metabolic reactions are condensation reactionsc7 m5 y1o;mokytji4k 9?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the j1n ute8aenf0v- +j2x2ksl g, rate of enzyme catalyzed reactions can be measure 18fjvut20engk jas+n-lxe, 2d.
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 chemical reactions, give deln48 ,8eve g7p)ojqn one exampden eoe7 )g4lj8, qvp8le 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.