Which of the following macromolecules describe a typical enzymevr *lr6sd0j/o?

  What type of reaction is photosynthesis?dnvoa+v+o4qr/+ tx:d

  What is the substrate for theb2dqx/5jev 0e wz0)mv: (siiv4i+lfq enzyme lactase?

  Which of the following stages of cellular respiration takes pld1t juy 1p5 ..owt6cuhace in the cytoplastod uju1p.c1 y. h6t5wm?

  Which of the following would not be useful in determining th+qv+ 8y njc+)vtx dl,le rate of an enzyme-catalyze)dvlltc, j+vx +ny q8+d reaction?

  Which of the following processes may be described avd j57r 2pzo1ts catabolism?

  Which of the following statements is best depictediqyj g*6*x wz27dwxhm 4h6w9 d by the figure below?

  Which statement about enzymes is not tv0j0x ld42yap ag; -cg0jrsd6 rue?

  Which of the following graphs best illustrates the relationship between temperat blk.x(v-mo0rure and the activity of enzymes such as lipase?b kr.x0 ov(-lm

1.Sketch a graph to show how increasing concentrations of substrate affect enz;j2vh9xvolc/ bg 557zq rptb9y nkw( .ymevko7yxq .5v;9l( bt 29gw5rpz jchbn/ activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catxjvg c(4rf yc)8((azb n(ps /yalysed reactions. A diagram outlining the Calvin cycle i b /z8y4pvxfa( )y ng(r((ccsjs shown below.

The image below shows the catalytic site of an enzyme. The su.f 1oa8sxj7 dubstrate is shown in black an s.8a7xdjo1 fud 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 descript29nyh w4a 8vfhi mkdu5c*:p0r ions of the enzyme catalysed metabolic pathways shown b04 v8mn h95h2afdpwk iyuc* r:elow? Letters represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-u8lqa1h - vd6bfw/eh1catalysed reacti86-b1uh/ avq hl 1fdewons?

  Which of the following correctly describes photosynthes xm+xrwq9t *j00v cs9spwl/z 5is or respiration?

Many enzymatic reactions happen as pathways involvingy plk8) qa9-vd multiple steps and multiple enzymes. k- avd8)lp9yq

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

  Which of the following best describes the inhibitor in the image belowo7aw8s *hol3 -qy+gl;dv;fzd?

  Which of the following statements are true rf+w m:l b,cz*segarding regulation by end-product inhibition: fwlszb,*c m+?
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 shoj aa 3k7fp(7cuws the structure of the lysozyme enzyme. The darkened structure in blackf(ak 7 cu3j7ap 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 used to study the effect of temperature -m/nozyhr-:-wrj vu w4r 9-bgon the activity of t/wmg-- njr 4:brzo-w-v ruhy9 he 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 desu0t ie+-/ne+d0+tt kxg* u;fmefat s- cribes how enzymes interact with substrates to catalyze rm-fditget-eat/+; uns+0 f+x* 0uekteactions?
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 measuz1pfe;e*;w-u -gitd o red.

  How does denaturation changz+ hv mc; ivb4)/gmo-ee the properties of an enzyme?

  Enzymes play a role in catalysing react kyv*nx 3j-)z.bij cj4ions. Which of the following statements are tjkn3-. x *z4vb)jyci jrue?
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 mammalx 1z3/61 jr hkl8tjxyls or endotherms from ectotherms that have fluctuating body temperaz1jy683 h lrxx/1 tjlktures?

  A metabolic pathway that conr hiwz+xi f6+z9vo; o8f)*evvt/l)i nverts threonine to the end-product isoleucine consists of five reactions. Threof9+fih wrivxolt/ 6z)+i v*vn)z; 8eonine is converted to 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 increasing pH on the rate of an enzymatic reactiospjbnf xvf6vw2y*9+zx1 q*)bn. What is occurring during the phase labelled section X ifv9)n bqzv bjxs6+w2fy*1 *pxn the graph?

  An experiment tests the effect of changing substrate concentration on an enzyj)qmc1*i/mw h matic reaction. What couwijc1/h*) qm mld be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to +a;+7g eszm )i ;5heg2)5qi f: nbrttblihz0aisoleucine.



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

  Enzyme A (Enz A) was immobilized on a mkm 70dp 2 4exdrh(fyf2atrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyd20d(p7y xhf r2m4ekfme 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 followincat *.m w;f 6puqvf4/lg is the best way to kemq6f cufwpv;4ta /l* .ep enzymes active for a longer period of time?

  Which of the following describes so/qaf( y11tnh9p5f-cn6vbog7 2 jyuo ume types of extracellular enzymes?

  The enzyme pepsin hydrolyses pr*c1v)rubxi.n;h 0 rv moteins to release peptides in the stomach. A study was carried out to determine the effect of increasing subs; rxn1v*0.)rh bvmiu ctrate 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.fi vk88fgu*m rp--hbv ocl. / enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently*l .bf.p- vko-/g8ch8umvfri to the reaction, and the activity 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 cut a turnip root into small cubi*i8zq*,)6sc zsb q goes. They measured approximatel,q6s o*gib ci szq*)z8y 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 t2hlg e: 5c*.rh:zppg9o q0 pzbo the enzyme HMG- CoA reductase can lower the bqppr z0p 5hgz hl:9.2oc*e:gproduction 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 are0aa rql*xjp ,7h06r8*jmh 5,a oakd yy 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 reactiobdgmz g+iog9) h,+e gmg ecz8(1hz7- qns in the classroom and were given an experiment which demonstrated the effect of temperature on ge)eg, 9zghgz1o zdhb7m q 8+cgm-i+(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 the efficiency of dre9n qa9:qq wh1ty)3lactase activity is tested. Which is an appropriate dependent variable for this experimen3dte y:9awqq nq r91)ht?

  A study has been conducted on the activity 3p 0 .yfcjbn/hkw1qv7 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 produce lactose-free milv bqyc.3k0h/ f1wpn 7jk.



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 c,sqwyuz-60pip24.b- 8) wkzrqapz jto find new drugs for treating patients with malaria. Describe how w6zpc0p4-wpq b z82 ,.q)-uaikrj yszanti-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 concentratil a)1nacbyj1 -y srf8-xxu ;l)on of an enzyme affects the rate of reac8rl ;)n) u1xal-1-cajyyf xsb tion.
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 syn-iz cy) bttogk:9 vuq-, ze4g:thesized through metabolic reactions. Which type(s) of metabolic reactions are cond,q gt- uob4y-tve9i kz:g:)czensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed j*2s+2h iwh)gvh i /bvreactions can be measu2+2bv) iv* ihwhj hgs/red.
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 ex+n5n tui3zl) 7oupkxfp--8chg k:k1ftracellular chemical reactions, given okx- 5zppc-:tu)i+ 3 7glnf8 k1okhufnne example 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.