Which of the following macrpi3 b6cx,-j( jv*-gl7qy mvicomolecules describe a typical enzyme?

  What type of reaction isrc8.4-k9k4i qmgxx93ap w ( zp6oqt- jgjz(cx photosynthesis?

  What is the substrateem.pe2 4hwh/hnclo. p t-dxw) 04l* st for the enzyme lactase?

  Which of the following stages of cellular respiratioxd+nr ndj2, s w12mn9gn takes place in the cytoplasx2+9sd2wg,nr d nn1m jm?

  Which of the following would not be useful in determyewzuh8t(xs9t. vi: ls79v 3h ining the rate of an enzyme-catalyzed z w 8.(shs7x:tuv e39l9tiyvhreaction?

  Which of the following processes may bet 2l.1dx lbf5f,gez lq8kg23x.r dd0o described as catabolism?

  Which of the following statements is best depicted by the figure d uzl g1x 8d3)s.*ruw8 nga9cr :9uaiobelow?

  Which statement about a(a3 r7+wz ylqk ym;3jd:k o/oenzymes is not true?

  Which of the following graphs best illustrates the rlwb +,dvd2hh9elationship between temperature and the acti,lwh+ vd9hb2 dvity of enzymes such as lipase?

1.Sketch a graph to show how 6cvb +q1-zlcigp) m*bincreasing concentrations of substrate affect enzyme acpgc)b b*+1ci qlmz v6-tivity.
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 outlinixp,wr5)nj8 t q-0cp htng the Calvin cycle is showj,xr)5 pctptnh0-8 q wn below.

The image below shows the catalytic site of an enzyme. The substrate is shown ic/6byx znl8rp,5q j4l n black a84 zr, qb/5pxnlj6 ylcnd 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 descriptions of the enzyme catalysed metabo)ksn)cw, 2hom lic pathways shown sm hk2,wn)c)obelow? Letters represent various products of individual reactions.

  Which of the following describes the oja*h+ x -q0t/h8josurole of inhibitors in enzyme-catalysed reactionsu -x*o sjq0h jo+/8tah?

  Which of the following correctly describes photos:d 5 tgad8uq zhg)6*kcynthesis or respiration?

Many enzymatic reactions happen as pathways 0lk:mws5 .k 5tzcrri;involving multiple steps and multiple wz5: 0s.5rkkmcit r;lenzymes.

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 below* t9 a3hcd; 0l(uuf.y1um nbvn?

  Which of the following statements are true regarding regulationqk 3qssyc1 39 tktyl:b 6ck8d8 by end-product inhibitio3tk 6s : k 188qklcyyb9cs3dqtn?
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 xkh bx)+ndw5tu/er. 0 shows the structure of the lysozyme enzyme. The darkened stre)nxb/w+rutx k. 05 dhucture in 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 used t4t kmq3(x 7m usdg/kgn mvw:3t4:xw jmk, 01mno study the effect of temperature on the activity of the3w:dk 7vk 4m4mq gn j/3 nmmtmsu,w10gxk(x:t 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 hokga2wy*o( (t sw enzymes interact with substrates to catalyze reactiyt( *a2o(gwks ons?
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 reaction1g:sy,t /oujcq+uyd:s can be measured.

  How does denaturation change the properties of an enzyn8jg,7u g f3ynme?

  Enzymes play a role in catalysinfu b4jgu b7f:y:p .*yfcs6 3jdg reactions. Which of the following statements are tj. *37f6gpyj4cu:b:bus dff y rue?
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 orx9:dj0myw g 4y endotherms from ectotherms that have fluctuating body temp:490w mgydxjyeratures?

  A metabolic pathway that converts threonine to the end-product isoleucine r )xhdi7ov) p 22gp*7df:7keyh4 cnkbconsists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleu 4rv27gyhfd 27* k x)hb: e)pikond7cpcine 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 15b hqhldq./zreaction. What is occurring during the phasehq5z 1h/ qld.b labelled section X in the graph?

  An experiment tests the effect of wa*6ehl5xuz 4 / xm8wzchanging substrate concentration on an enzymatic reaction. What could be the independent and dependent variablh zx8 ew5wz/a64 uxlm*es in this experiment?

  The diagram shows the pathway thatrrd;p. b5vx5btf9 y) f 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 matri 24th to6dajaht 14oa4)q7xppr:i j *ox and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x) pa2 tt*7q:ihroh4aj44oa pxotd1 j6-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 iohgro7uhf)alp4m w44 dfd6786*j tc ss the best way to keep enzymes active for a longer 4h 6dl ro8ow 4pd*6s747hfcutfa) j mgperiod of time?

  Which of the following describes some types of extam avb,r -5(nuracellular enzymes?

  The enzyme pepsin hydrolyses prot 6rk0kd j z wy5z+784sdi *c4epnuzum-eins to release peptides in the stomach. A study was carried out to determine the effect of increzzs uk78n+we4k 5-y pi 4*cj0zr6udmdasing 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 enzyme with increasing suf 5:jytgl 98ldbstrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the 8t9dg5yjlf:l 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 sex(4hxe 2g5jsu. y sb-mall cubes. They measured approximately 5 g in a wbjsx seux5y4g2 .-(e heighing 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 the enzyme HMG9s75jfz;qyhedhwsx9j;1-n xhw8y f- - CoA reductase can lower the produc;9w-q1fx9h-zsx;7 d je wyh f hyj8sn5tion 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 +33ov2j2q nyiiyggb2 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 investiga s.f1o51k* ( 1dysuf mzjavqu-(7x yjating metabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolf *f vo7ys j(u5.(1q -adx ask11yzmjuic 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 effi30q eiz:tzydk, q0 a/qciency of lactase activity is test3qqz0dt ,y:k e/q za0ied. Which is an appropriate dependent variable for this experiment?

  A study has been conducted onw s(,p( q/lefbes8yz- the activity 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 lacl be- /s 8ywe(qz,(pfstose-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 tio2fm z -12srrzch 6+wreating patients with malaria. Describ26s-f ri wmzhr1c+zo 2e 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 concentration of 6m q/u ns*oq6qan enzyme affects the rate of reactnm/6*qu6qq s oion.
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 metad aeb g-,o0c7bbolic reactions. Which type(s) of metabolic reactions a ob-0,cb7gea dre condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzymn*9g6xhw; yb51r uyone catalyzed reactions can be measuredyyx;gn 6 huob*5wr n19.
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 re4zkj +p 02uvybactions, given one example of each type ofk bvy z40+ujp2 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.