Which of the following macromolecules c29qi/ h bp+/oirz8wedescribe a typical enzyme?

  What type of reaction is photosynpt4 aa7fza h9on,1:sithesis?

  What is the substrate f+b mh o+z+(yjasl4q; 1jge:fnor the enzyme lactase?

  Which of the following stages ofp lxl zb:8uiw *-0h9fj cellular respiration takes place in the cytoplasm? 8-j hfi9b*x: 0pw lzul

  Which of the following would not be useful in deter -(*jc , .rpw/x6kwkwem2 axdogq9n 8mmining the rate of an enzyme-cata- qgkwj2.6m rwpx xed89o(/n mw*,ak clyzed reaction?

  Which of the following processej,*ks*bow f/f3 2mbwps may be described as catabolism?

  Which of the following statements is best depicted by the fiwajgm79w5s z-m.3 ,t: mffixm+7p0p myceu8 bgure below?

  Which statement about enzymes is not trukdqbbl-sbj b8u t40 zqm-f(;0e?

  Which of the following graphs best illustra8a;jbh ibdd4m+sl w;zcc;6 s +tes the relationship between temperature and the activi wm6sb zh+abs ;l;;j84icdd +cty of enzymes such as lipase?

1.Sketch a graph to show how in0 psf(; di(h a73rai.+gpv lsy()ls xscreasing concentrations of substrate affect enzym7ipgsla ((vp r. ) sdyasf+ 03sl;ixh(e activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a stz ,u6rfftl*wwz:d(pm p+ 8s:eries of enzyme catalysed reactions. A diagram outlining the Calvin cycle iw:z+*w8lp (uz dr ft,pm :6tfss shown below.

The image below shows the catalytic site of an enzyme. The substpu+vxfi +kzg1)mp68l q k,r9f rate is shown in black and ml)q+g,i 1xk vurp6+pz9k8ff 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 descriplfupowdm j(tm;;:i 1rx+ w a,nx0s5z 0tions of the enzyme catalysed metabolic pathways shown below? Letterz,m1xswud;maft r0j: xp loi+0(wn;5s represent various products of individual reactions.

  Which of the following describes the role of ojk,y al l.,;kinhibitors in enzyme-catalysed reac;y.,lklo ,jaktions?

  Which of the following correctly describes photosynthesis or respiratio:agl.sf v 5nk j7(2vrin?

Many enzymatic reactions happen as pathwayvz leydep of( y2 98(hdb4wm21s involving multiple steps and multiple en4m2 (1bp vl2yz ho9deyd8w(efzymes.

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

  Which of the following best describes the hk ky/,a;f:s zinhibitor in the image below?

  Which of the following statements are true regarding regula;+s7cd+zu qvtanaagn6/j6: nw ta0u( tion by end-product inhibition +vcaa0g7 uwznunj6/ q t;dnt+6a:(as ?
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 enzymez3 yjvo4z9 dr-. The darkened structure in black is the substrate and is bound at the active site.3jd zy ro9-4zv

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

The equipment below can be used to study the effect of tempejjmm y4-j0,s csys9h:-pvd s)rature on the activity of the enzymj0sp9 mss)s 4 yd:,ycv-mh j-je 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 enznf-21xp*vu5t zp cuf+ymes interact with substrates to catalyze - pfv1p u+tc2u5z*xnfreactions?
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 cataljkp6j6q0 pt:w k/w+riysed reactions can be measured.

  How does denaturation change the properties of an enzaj*c+0p t zwo7yme?

  Enzymes play a role in catalysing reactions. Which1g7who gm42/t:ch hueko0 zt : of the following statements are true?04o 1tzt:hg ewgu kh7ch2mo/:
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 from ectobtx u i0tz,(byx* v8m3therms that have fluctuating boxb3* ytztv8,ubmx (i0dy temperatures?

  A metabolic pathway that converts threonine to the end-product isf :6a.51guvjdmxco:ql.hm f gq j3p11oleucine consists of five reactions 1aj 1uh.p:3q dfgl6mg mjfvxco.5 :q1. Threonine 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 enzymati+o+,3ycley e ic reaction. What is occurring during the phase labelled section X in the gcyel,+3yoe +i raph?

  An experiment tests the effect of changing substrate concentra9 z u8t:e9v66a*qo,jwa xr5yec nf+totion on an enzymatic reaction. What could t*oa8+r9,u:w9 xty6e6 nq5 e ocvafjzbe the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threont v1o)f-lz7xiine 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 i( -v 3phjnb lgf;9(g,3affuwy ts activity was compared with that of a free enzymf(f g(- jbwulv p33h yf9gan,;e in solution. The graph shows the 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. Which of th1t lg0z7b6m5qrrk)b fe following is the best way to keep enzymes active for a 7flrkt 56zb 1 mqr0b)glonger period of time?

  Which of the following describes some types of extracellxhe nup/wd2,ir1( p r0ular enzymes?

  The enzyme pepsin hydroly)lgt cc66tix3uam(s qqi5.u *ses proteins to release peptides in the stomach. A study was carried ou3) ga5*u t6m clq.ts(ui6xqict to determine the effect 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 reaction4q7w inn1x qa dfsc l15x(r+;o of an enzyme with increasing substrate concentration. Similar concqi7daxsxf;o4+5nq l nw 1 r1(centrations 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 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 al8 t ldujv j*px1i2w z.:s89kxe.mp:a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenizepj:a. w txvj89k ex2dpi:lzl1m. us*8 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 Hn -l d6uh5ckm ckz ,( rpg -v0w:)cdanvg8s:6yMG- CoA reductase cw grvhcs-z0unn: gp:a-, ()d5kcyd mc6k l8 6van 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 are involved in denaturatio )juz:yf.iuivw1e) k ,l;.p4 fb.rp jxn?
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 investifi7/)pf n vcox .r4i9kgating metabolic reactions in the classroom and were given an experiment which demonstrated the effect of tem )vf9oi7 /ckxn pfi4r.perature 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 effx rlg -q;cb6pebiwq:no;i1 ( 7ect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this wq:6ine xb ;(ic-7gb rloq1; pexperiment?

  A study has been conducted on the activity of a s//*m sakzi.oqpecific 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 milk.oi/zqsm ./ak *



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 9mt1(i6s9okn *c6z *e pwe bnd /(zvwbwith malaria. Describe how anti-malaria* kwe 6w 9pbi9(bv* m1tc(nos 6/znzedl 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 an enzyme affects the rate of r.1:a254jd ra scxz jzcfg5+u :hhy/w qeactioncy grz1cj:u./ hzw:q hsd45a2xf+5a j .
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 broke m70l0+v jygbhn down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation reactions?0vgl jb07hmy+
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate45mi uvf6axb 3 of enzyme catalyzed reactions can be measurevxmia u46fb53d.
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 reactions, gi dajs q,b8p(,w1su8y6sggt m0ven one example ou 8sq p,dms bj06wag,s8 gy(1tf 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.