Which of the followin tlosta;dr4b:r9h 8 o, ma1q(og macromolecules describe a typical enzyme?

  What type of reaction is 3;el))i r(ago w4t acyphotosynthesis?

  What is the substrate for the enzyme l6q3fjrk.l)/nh6 fkfdactase?

  Which of the following stages of cellulaiu;:)ah nus 4rr respiration takes place in the cytoplasm? ; uhr:4siuna)

  Which of the following would not be useful in determining thm )two6q0s .nwe rate of an enzyme-catalyzed react 6qtmnw.wos)0ion?

  Which of the following processes mav l2x )sa7tm1rc vr-:ry be described as catabolism?

  Which of the following statements is best depicted by the figurkj,y 9kmgnn.88iu sd/e below?

  Which statement about enze 9.q3eb /e y0 bq3nhldigs jxu7*db+.ymes is not true?

  Which of the following graphs best illustratexilqy6-l0 z(r s the relationship between temperature and the zy( -6lrx0qliactivity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations n2wzxxlzh:7y4l3: 6e1 a kledof substrate affect enzyme actiz3 ee7lw1yzah6lk2xl n4: x d:vity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactions. A diagram outr: lr:d2kjny4lining the Calvin cyc::4d2rkr jynlle is shown below.

The image below shows the catalytic site of an enzyme. The substrate , 4k5sdypl;z9o t2stfis shown in black and is bound to the activet94tzl2s pkyfd5o,;s 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 cajfp4ru .b9 ytra;g-:ztalysed metabolic pathways shown below? Letters represent various productsru -aygtj9b4: ;zfrp. of individual reactions.

  Which of the following describes the role of inhibitors in enzyec o:vwo76;)gsia 5 ps0hf+oi80 ar ikme-catalysed reactig 7riw o6a)c:h+pi0o;8vs e0kaoi5fs ons?

  Which of the following correctly describes photosynthesis or respirat4p(g*zp ;upwo ion?

Many enzymatic reactions happen as pathways involv6 e)*ani ;lb2yav q/gzing multiple steps and multiple e *2niaz;va bg)l/q6e ynzymes.

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

  Which of the following best describes the inhibitor in the imag(9fs rc:n2l one below?

  Which of the following statements are true regarding2bt:izp.i3 iny.q7*e*+ h- h urzwr qd regulation by end-product in-ht*dqb ri +n eiw.qrh2uy3.7 *zzpi:hibition?
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 thejgtmb;u.s 7y * lysozyme enzyme. The darkened structure in black is the substrate and is bound at the acts u;t.m*g bjy7ive site.

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

The equipment below can be used to study the ef/i1n+/tqzd t rfect of temperature on the activity of the enzyme /zt r/iq+n1 dtamylase.



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 4y*y7d6p/dpx m1zt fhsubstrates to catalyze react1f7tx 6mddp/*pzyhy4 ions?
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 k y;w4p47)bewn0t s3tr8f i xwcatalysed reactions can be measured.

  How does denaturation change the rq -yb/8q3ugx properties of an enzyme?

  Enzymes play a role indrod9*ir:(q1 xa l3vd catalysing reactions. Which of the following statements are truldixo1d d* 39q (r:rvae?
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 fr( f0og2bcd,t 1n yrlj/ -u9pfoot96l fom ectotherms that have fluctuating no12 6,cljb-utt o /(99 f yo0dfrlfgpbody temperatures?

  A metabolic pathway tk r.. hui28 : jx*kaxqtb:qn/hhat converts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequeqt:8.bnkik: 2r.aq/h *xxuj h ntially 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 8:a 89c5zky do4pih cyrate of an enzymatic reaction. What is occurring during the phase 5a: 9zy h4c8 ody8cpiklabelled section X in the graph?

  An experiment tests the effect of changing substrate concentration o.q,f8( xt0 zjs1at qcrn an enzymatic reaction. What could be the independent and dependent variables in this exqsr8 .(xa,cqtf1j0 z tperiment?

  The diagram shows the pathway that converts threonine to isoleucine3 wt1go;c8jvrqf1 lr*.



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 r4dir ze -udro+bwz:11sp+8by rdw9-was compared with that of a free enzyme in solution. The graph shows the relative enzymep-1b4+ d :orer89ur dwb wdi1-zy+r sz 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 ej4 0lz69l9 n9c2cqzu sa mdh1)ln r7ijasily denatured. Which of the following is the best way to keep enzymes active di7 02)4 zmhcjs69 nz9rlc9lnqjl 1uafor a longer period of time?

  Which of the following describes some types of ext, lpz;9+s hryfzl 28r jb9s0jeracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the ste:k 1 bjgxt-3*c0zqjmomach. A study was carried out to determine the effect of increasing substrate concecq j etgmk*0j3:b-xz 1ntration 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 showy8u o3mioamu8) 40bu us the rate of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D wer8mo a8u )0um youi4bu3e added independently 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 activ0zm 0 w .b1*hw7wtmdiyxo )e/uity, 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 was filtered and the liquid ex whdmyzwtm1oe)w0*0uxbi/7. tract 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 iso3j wqb) o4zj65nn4of shown below. Inhibitors to the enzyme HMG- CoA reductase can lower thefoo jwj44qz6 o nn)b53 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 involved in denaturation?lr6 r4w 2r*nbq
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 classroom and were gijl2z9r31-. jrqjlrr6u l:wah- /xyq6p fge3c ven an experim y63hf lq96qjwr/.ra-e 1 l-3jp2xruglc:jrzent which demonstrated the effect of temperature 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 effect of increasing temperature on thts:wedfa e/.s9ff1 4ie efficiency of lactase activity is tested. Which e/i9s:w 4f1. deasfftis an appropriate dependent variable for this experiment?

  A study has been conducted on the at0x8)qi aw.y fctivity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a)0q.ywxtif8a 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 for treating patients wiy3k f0;pb bcsv0q.1 fnth malaria. Describe how anti-malarial drugvys 3n 1fb kb;f0q.p0cs 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 th1)soroadt lem cz247l32 p n;te rate of reaction. 2p o23dlrze14 ltct7oams)n ;
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 thrt5sxbw8 ;l -duough metabolic reactions. Which type(s) of metabolic dw 8-bt u5xls;reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cay0:qimgon km6:.ztk2 talyzed reactions can be measured.6k:zmim :gon2 t. kyq0
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 extracellule6-;4gh-( d by*mui(et mquh xar chemical reactions, given one example of each ;yh-t4me(bqm* exui dh6u(-g 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.