Which of the following macromolecules describe a typinobyj -o2tlv2gkg; al7* z(9ical enzyme?

  What type of reaction is photosynthesis?t( w+eca cs*jxy;-k-d

  What is the substrate for the enzyme lacfv k,6lz,d:tktase?

  Which of the following stages of cellular respiration takes place ihni.b rt3d; yn(jcl-9n the cytoplasm(ycrhi-nt 9 ;bl .d3nj?

  Which of the following would not be useful in det42ncm/0k0cuuz zgv g*ermining the rate of an enzyme-catalyzed c0gkv*2 0z4cnzm/g uureaction?

  Which of the following processes may be describej:d8uav974pjl 9 j mb.-di/vj.vbu cud as catabolism?

  Which of the following s1 c+9oh q7c17dyjqa6sv5bqsctatements is best depicted by the figure below?

  Which statement about*z36va- dg*v mpt 6 kc;6dabhqhub2*.gags z/ enzymes is not true?

  Which of the following grapkov;nfg5 yot60(yx rxge+z86hs best illustrates the relationship between temperat0nor5x f z6y(;t ekx6+yo8gv gure and the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substnr )/pdu sopw y,;(p-nrate affect enzyme activity)opwu( dyp/- n ;nrps,.
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.vuzorari2o8nr 5k*0 : A diagram outlining ti :5a8roz2n0vko* rurhe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown xyl -3sa2e5sgc2m8cb in black and is bound to the gc8-la 22ems5 scx by3active 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 descsq/(2 .n rvezpriptions of the enzyme catalysed metabolic pathways shown belowne. r/ q(pszv2? Letters represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzymbkszft1s7-8rj) av n9 e-catalysed reac9)z7 nb jas -8tfr1vsktions?

  Which of the following correctly dvzll1;4gfi +s escribes photosynthesis or respiration?

Many enzymatic reactions happen as pathw9ea io863 m *lk27ni el cujdy8y4q6rjays involving multiple steps and multiple *aelmn382k79 o64 q 8celiuy j6ijrydenzymes.

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

  Which of the following best descrr; 5si8ovdkcg0u98)*ot;v cg szwr.wibes the inhibitor in the image below?

  Which of the following statements are th,vlu a++dpf )c xe(:erue regarding regulation by end-product inhibition?ahce veud(:f l+)p x,+
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 the lijsz8gga2ro o ez(z1h1 gh ,j0jai8d*ji07h )ysozyme enzyme. The darkened structure in black is the substrate and is bound at the a8082djsi1 ,ojie(zh7 ga 0 zahgjrg) oh* izj1ctive site.

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

The equipment below canwc qn rtmj a979m17a,s be used to study the effect of temperature on the activity of the enamswat 7 n,97qr cmj91zyme 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 substratfxbo(jhr6l - -es to catalyze reb-h(6 xlf ro-jactions?
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 catalysexehmh8 0h j*,i kw0 8cw0mw+gkrle9g/d reactions can be measured.

  How does denaturation changs2t d d:-)d0k)xczx axe the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statements opij *yp/29p-mwz,us- sb wj. are true? iub sopw. p ypj9/mw -s,2j-z*
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 mammal .dlvw,aex 5b-6 w/wfhs or endotherms from ectotherms that have fluctuatf e,h-5 ./xb6wvd awwling body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine wvr +e-t+fzut17v- phconsists of five reactions. Threonine is converted to various intermediate products sequentially by di -tzvp17e+ wrtv+ h-uffferent 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 ey2:wdh; qu2cn7 *6jdcuk*go l ffect of increasing pH on the rate of an enzymatic reaction. What is occurring duowykd l6hj2u7cu2nq: *dg*; cring the phase labelled section X in the graph?

  An experiment tests the effect oft 4szrj *7ou*e changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variablz*7e otujr4s*es in this experiment?

  The diagram shows the pathway te 1d y*4x.ngxmbt8 v(dhat 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 immos3fc +tj u)*1g jwuv (f+caiv.bilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis+j3v1 .)vgccfjautw ( isu*f+) 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 folzyl b m/)id;0/diu t2ilowing is the best way to b izdymt0idi//l) u2 ;keep enzymes active for a longer period of time?

  Which of the following describes some types of extracellular ;d2 wadaz*(zcenzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the st) mx.vg b i/h r5v*u9u*6wngegomach. A study was carried out to determine the effec)ewru9 .*v* hu56/mggxn gbivt of increasing 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 s7y4xfrz 8o- jeubstrate 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 ma84o7rjx -e yzfrked 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, aj +l5+*le qdon 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 extract was stored ij+ e*+n 5dllqon 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. Inhezblyjsx kx0u9x8 xz e1.p6h+hyz)85ibitors to the enzyme HMG- CoA reductase can lower the production ofbehe 5x)plzx88 z hk60xs y1.9juxy+z 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 involve,uv4m(pa *- +caevv mhd 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 investigatna q1-qob+eq/x . ck1*,kzesiing metabolic reactions in the classroom and were given an experiment which deq/q1-x ,ko1cqz*se bk+nia. emonstrated 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 the efficiencyi,2dcfvy4/qqk ,gs7zxe f. atq )9. gl of lactase a .qq7.dkc, a)gsf vt4xfl9 zy/,2qeigctivity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of ags wx5(l;s5itf j6*62hssj x an (/nos specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactasx(sgs6a( h2i/twlx6 5*o s5n jsfnj;se 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 drugs1z:r idi0t0-uqwygac h:57ib7 f*igb9. zk zk for treating patients with malaria. Describe how anti-malarial drugs aryfd:0itqi kuz: .1*rbzh0gcbi 7z79 k-ga 5iwe 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 thpa vlf l8o kn89(n5;obe rate of reacp5 ok ( nvo8f9nb;la8ltion.
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 metabolic rbh4tyzhbi (qy vy2)l;qpt9r+e )l1v:eactions. Which type(s) of metabolic reactions are condeby94l i hplhe))tqtv 2zy+b r y;q1:(vnsation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can - jua4-a jygie 8*hvbutj8 l 82, qh54e-alwsibe measured g *-lthbj2,8ijea-v8 a8ueqajy4 5 w4u h-ils.
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 reactimssllyd (z2 8y1iy:i., wt-uxons, given one example of each type , xdm. sy8(tilwzs 1yu y-2i:lof 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.