Which of the following macromolecules describe a typi .coho:qhe/dc2: iv+au/ye*bcal enzyme?

  What type of reaction is photo8wv2av dua7hj/yi;+t(ek, w isynthesis?

  What is the substrate for the enzyme lactar7q x 4u4tn6he6z nbtl1mb( a1se?

  Which of the following stagesk 1n 2ew.(i *mic,plzo of cellular respiration takes place in the cytoplaowciz2p 1(mn il,.*k esm?

  Which of the following would not be useful in determining the rate mi 7h3eu(1tlvof an enzyme-ca 7vi3ulte mh(1talyzed reaction?

  Which of the following processes may be described as5,tg -4b fukas catabolism?

  Which of the following statements is .f 9.fwi4xa m gt1z;(iayqc0d best depicted by the figure below?

  Which statement about enzymegbqnax e, )a 4w)xx20j:kv9okobb /5ys is not true?

  Which of the following graphs best illustrates the relationship between2etl u 6v5y k/v2p)kag temperature and the activitygeavy5t v/ 2)kk p2lu6 of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of2* iqu(hv l w)do,2yli substrate affect enzyme activ v ),h di2li(w*y2luqoity.
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 diagram0*2nlxtu 12 2 vaduwov outlining the Calvin cycle is shuda n twul*o2x102vv2own below.

The image below shows the catalytic kmlgxyp:/fl( 8q*rm. site of an enzyme. The substrate is shown in black and is bour:glx(*lf y/ qk8pmm.nd 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 catalyse09s, zqy(onznx;: fved metabolic pathways shown below? Letters represent various products of individual reaction ;nvo9(nyzeszfq: ,x0s.

  Which of the following describes the role mga8ntn; v. co j+)5flof inhibitors in enzyme-catalysed reaction+. tv8ojnf)a5g;cm l ns?

  Which of the following correctly dewn 05(x(c )pks3yptg zscribes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and; rx(xsu8ncnc l)77b-v tt r5f multiple enzym tu8c(lnfcxbr7)5xsn tr 7;-v es.

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?yw;y mjz.u8 z+kox :+abii0b*

  Which of the following statements are true regarding regulation by eywk:)q,r8* -br0 bqxn bzebw*nd-product inhibitionyw*8b: q-nkwe*rz x0bb,)qbr?
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 enzyme. The darktp/ muoxx/pe1hs80 x; o v:br;ened structure in black is the substrate and0ho /xpvxb/stp urx:o1 ;e;m8 is bound at the active site.

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

The equipment below can be used to studyeq f*6n r uu.5(kw/rvp the effect of temperature on the activity of the enzyme .(ekqw/ur frn p6uv*5 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 substrata( o*v1s/zk oxt:z6xoes to catalyze re:( s/k avxo1 ooz6tz*xactions?
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 reactionsln d*5kf( cek6(q,ssx can be measured.

  How does denaturation change the properties of an enzymw *r(;jthgkqnlv6 s7( yfa a,0uq 40hse?

  Enzymes play a role in c1h+4uas r .ta d93lcrgatalysing reactions. Which of the following statements arec tsh13 ua4.ldr+9gra true?
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 endothe ig;k n1c2my(j* fr2cmgy/n)u rms from ectotherms that have fluctuating body temperatures?r1 *); 2mnyc cnifkj2m(ugyg/

  A metabolic pathway that converts threonine to the end-product i-*m7ebd* eov qh kp36csoleucine consists of five reactionse o*h*cp eq-6bv3k 7dm. 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 effea)cra/ewwk303b.i) z t1l zwwct of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase lae /lt0i1wazwkw)3r b3a z)c.wbelled section X in the graph?

  An experiment tests the effect of changing substrate concentration olg)ucibzc:shv8) (sz: . 8k,twa t; ipn an enzymatic reaction. What could be the independent and dependent variables in this experwktv)gz ic h8 s zucs(:);a.btl8:ip,iment?

  The diagram shows the pathway that converts threonine to isoleu+ht;;dvp6/2ijvs2 cf,lob ezcine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobilizevg- ed*c:jc f)d on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axi)*fgvd: j- cces) 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 following is theip wh.ippqhs3f fy0 :3 al0;:m best way to 3h0miq3 l.pyf:isp p;a: fw h0keep enzymes active for a longer period of time?

  Which of the following describes some types of extracellular enzymgp)mu n 1o5xi*j3uhrk0n9 p(ues?

  The enzyme pepsin hydrolysescb jmps,)uu b2d n42(q proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at ad)2 bjc4u2qmbn s(u,p 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 increax 3p: j s8lasbv((i-ls0:mltzsing substrate concentration. Similar concentrations of chemicals A, B, C andbl0issv :-mltl((xa8s:p zj3 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 a vsu;9 uj*l,0 7wn,kf+w znnguturnip root into small cubes. They measured approximately 5 g in a weighing diu lwgw fs u,vnjn7z;0 ,k*9+nush, 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. Injphtum a8d 5r-te+qbi+ /5,xfhibitors to the enzyme HMG- CoA reductase can lower the produci5 /btx-pdmehjfatr, q+8u +5tion 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 denatu: g ezwryr4b2.ration?
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 gybyh okb:by , 2xr2qjp*645hsiven an experiment which demonstratedqboy :j,kbs22rhh56p x *yy b4 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 thnl,6l 4qa36 z7qcocave efficiency of lactase activity qnav3qz,66co al c7l4 is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conq1xs .k9jq s6sducted on 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 xjs1 .kss69 qqto 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 trea im0m s *p,;mex;bes*wting patients with malaria. Describe how ;we s e,bm*sm xp;*0imanti-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 an enzyme affects the ratjq u am na7tp,606kk8w+(hzi ve of reaction.zk h+a6wip8n ,kavju 0mt6q( 7
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 synthesw7 h 0(nlq.kj4;lpyrc ized through metabolic reactions. Which type(s) of metabol70kyq ;.wp (lc hrjln4ic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzwzsxs:x/q)o p4n *d)red reactions can be measus*xsrp) /4 d xn)wzoq:red.
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 reactionb rom. 8y)lzvy.-z77t pdij)s s, given one example oy dp yz7)7 -ltivb.8josmz)r.f 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.