Which of the following macromolecules /jsghvroqt4b d) f9 k r1ez81,describe a typical enzyme?

  What type of reaction is photosynthesinj4 n(n 286 wb4szldzcs?

  What is the substrate for the en2vsed nj8kx9-sj 7au yf,b5*r zyme lactase?

  Which of the following stages of cellulazmt:.xhgl b -kq0 ..qw6ghqk(r respiration takes place in the cytoplakmg6. q:x0(b .h -tqqhklz w.gsm?

  Which of the following would not cfr 2yy.m8+ ;i(arsld be useful in determining the rate of an enzyme-catalyzed reaction?.iy+f2ly c;8 r(amdsr

  Which of the following processes may be described as catabolism?-pr2usox- /bi2elnky;t d, (m

  Which of the following statements is best di6 2:rujm bsy w6auz1-epicted by the figure below?

  Which statement about enzy6c (juh7yi*g 8kic w1nmes is not true?

  Which of the following g*qfd31gak4+q j ; *f.;wz cgw hmioap(raphs best illustrates the relationship between temperature and the activ whad;j .*fc w; m4qoz1(aq*p+ fgkgi3ity of enzymes such as lipase?

1.Sketch a graph to show ho,y3i t/5izb,6s;w:0 heliytjv yml * rw increasing concentrations of substrate affect enzyme activity. ,z63ilv r:i yyje s0,t /h ;wbmy*ilt5
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a s.rc4tu4 itc) series of enzyme catalysed reactions. A diagram outlining the Calvin cycle is sho )t4sc.i c4turwn below.

The image below shows the catalytic site of an enzyme. The substrate is :*itvvkx hw-f0 si adapqt*6 hj1x,-)shown in black and is boundvi*10a vdh axiwxsqtp,-: )6h*tkj-f 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 enzyd fz p(kbdge :ud-70p5me catalysed metabolic pathways shown below? Letters represent various produckz:( f-d0bdepp dg5u7ts of individual reactions.

  Which of the following describes the role of inhibitors in ef ou2,qy;)x retzajb1f8 pt80nzyme-catalysed reacrf ;yz2 foa08bjp,q t1e)8txutions?

  Which of the following copqi1( t21d./ozf1e zywgtofb k rtz)b): 8w6grrectly describes photosynthesis or respiration?

Many enzymatic reactio0726xn2 plv/;qd;kvxom i lj ins happen as pathways involving multiple steps and multiple enzyme0j/ pmxiv x2 7;kin6oll2d ;qvs.

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

  Which of the following best desc god,)1q9:jcc* l fckzribes the inhibitor in the image below?

  Which of the following statements arex9zbj)n0gq1hy0 -p ( qekjnfz9 : hd:a true regarding regulation by end-product i0f9n0 :(dbjxz9 1hyjk-g)qqeza:n p h nhibition?
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 lysozyme enzymi(b e2oq yl;-(4ab0eam kfeb( ( m,sfxe. The darkened structure in black is the substrate and is bound at theobl 2 eff(e0a 4a(,((besq;xk ymmib- active site.

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

The equipment below can be used to study the effect of temperc.1i al+4d .klz vwrb(ature on the activity of the enzyz c la1(wkrdl +.v4.ibme 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 describ5e:hpmz)k/r)7su bdb es how enzymes interact with substrates to catalyze reacti: bdp 7)/ bukz)hsemr5ons?
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 reactionsvj40 vsum x:0e can be measured.

  How does denaturation change the properties ollwe7j t5bw. h9eb 9n2f an enzyme?

  Enzymes play a role in catalysing reactions. Whiuys h;du3hju:(z0+ wkj;j1xkx y)j x :ch of the following statements are true? jjhy sdw:;u0u u1z jk:j x3+(xxhk);y
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 f.awtydg)6u)6 rmh c:97ulv fi rom ectotherms that have fydfai66 r t7u)9m ug.hwvc :l)luctuating body temperatures?

  A metabolic pathway that converts thre*tt4di0h 7 2 ln75 -ubd)o6mzhadb keponine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine b*e d6np 4iz70h5tt)boudh7 mk2 lda-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 ibl4d6/koq:*1 t/wmeody y /bzncreasing pH on the rate of an enzymatic reaction. What is occurring dubyy/:odld m4e t1 //z b*w6qkoring the phase labelled section X in the graph?

  An experiment tests the effect of chbu/mmfz 1g 85zanging substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this z/u b5gmfm 8z1experiment?

  The diagram shows the pathway that cfw2w 65e nhwpv6j+ ,wsonverts 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 was compared wit;x 6kxe tj 7za. ks1glbx.-.pth that of a free enzyme in solution. The graph shows slb t ;xkpt1k..ax xj6 -7ge.zthe 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. Wqy9*gn 0bi- -jy)wmzghich of the following is the best way to keep enzymes j*-z-q 0 bn wggi)yym9active for a longer period of time?

  Which of the following describes so 9tlp/wf-8bitpw3p i+zj g q9:me types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the ston7 lrl 8hyg; 8k7c;b wur-hd6vmach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperature ofyb8;k-l7l whuvn7 g;8 rcr 6hd $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 p tfow.l:+ cc+ tmk92mwith 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 tc t:+p2kc.9 mwfltm+o he 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 i5a* zs.v: oz59gzuh dstudent cut a turnip root into small cubes. Tsz d :5az 9vz*.ogh5iuhey 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 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-eh ;4+zg x8rzklr8vvvw1 n ;f9 CoA reductase can+g8 vz ;lwvzr94f n18kvxeh ;r lower the 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 ;*k.7qho 5imf xthl3zare 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 metabofazr5 ;27ee5lfdd2 :-ri ol dylic reactions in the classroom and were given an experiment which d zr7eid-d l:2yd;2 l5o5rfaefemonstrated 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 increat0)bk0ay4 vb ising temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this ex v0bytk4a )i0bperiment?

  A study has been conducted on the activity of a specific lacth(aj.hlnb5,43hqsa kz1 d s8ease (Bg10), analysing the effect of pH, temperature and glucose concentrati4 k1.j,(n sqd zh3h5besaah8lon, 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 for treating patients dqbf1x/ad-fak h ,9*g with malaria. Describe how anti-mal/ 1hgafa,-fq*d9kdbx arial 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 us)bfg2r6m zdy+z7sgm 2i* *s f3oww4of an enzyme affects the rate of reactio)sb*mi +yf246 u3 27dwrfo m*zgzsg wsn.
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 brok/m+v5m q .ai9y4u6e ctektb.gen down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation reactions? gmi5aqeyuk6mt . .+ c9b/v4te
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cgyrj *ax;xa )8ybydx )d2h -/zatalyzed reactions can be measured. xa ;)ry)dgazdby*8 xh/-2jx y
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 intracelluqo*6lgfpt9 6 elar and extracellular chemical reactions, given one example of each 6gfp e*9ot 6qltype 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.