Which of the following macromolecules describe a typic+xoaafln/g8 , al enzyme?

  What type of reaction is photosynthesisg6rmh( /n3 qau p jo.8eyb, l(e-1ueil?

  What is the substrate for the en5ow(z/q * g+7 lb4utqt;(ewsfk 9qztuzyme lactase?

  Which of the following stages of cellular respiration takes plo 5eg:yod;rn 6a,:m6h3 pv wrwace in the cytopla;3:wno w 6y:vmde a5,6opg rhrsm?

  Which of the following would not be useful in dethd *i.b/iygo7bzd:d6 ermining the rate of an enzyme-catby dgi7bizd:h.do */6alyzed reaction?

  Which of the followingb9dm3i,;* hh.(sonabow zv 8 e processes may be described as catabolism?

  Which of the following statements is best depck oro9nrl6 m.h e z+/i0bux6,icted by the figure below?

  Which statement about enzymes grtjdub(qa /9+ pl( e7is not true?

  Which of the following graphs best illustrateq;vo v,1efkf 9yr2ix,s the relationship between temperature and the activity of enzymes s 1fvq9e,;rfk,ov yx i2uch as lipase?

1.Sketch a graph to show howfkaq . :;- mxei/t2lvx increasing concentrations of substrate affect enzyme act2ef t mvk.al; /x:ixq-ivity.
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 diag jg6 vz/nw)gbzn2 .hu4ram outlining the Calvin cycle is shown gv6z wb.j h2unz /ng)4below.

The image below shows the catalytic site of an enzyme. The sub0w-x1w i 1b. zyp8:3gbusisafo 0ku8pstrate is shown in black and is gbssua3- 18.o8ppyi1 xku :w zw0bif0bound 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 metabolic a s e2.f.v8k/it uw4a ,8ybzgzpathways shown below? Letters represent various produ,aae8u2 i 8zftk4/z..syvb wgcts of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed reapf q6 oc ljzxpj4) 5h27o7cx9ja.(d qcct c4 qj7qx p7xfdzlj(o o5h)jcc62 .pa9ions?

  Which of the following correctly describes pho:2c hk7*fpn mbw po/+ytosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and multiplypyon4plw/m1f y82,mkh4f g0 e fnoh km,0y 1pp/g82fw4yym l4 enzymes.

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

  Which of the following best describes the inhibito94hzmz9bl t,guszo -w9f5 cx3r in the image below?

  Which of the following statements ob hv(v:8sfgogrwsm1opc;3 7d v w591are true regarding regulation by end-product inhs9ogpf1wv1dgbc ;w5 vv:m o o38(7srh ibition?
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 str-btbqq* -um)1elc6k yucture of the lysozyme enzyme. The darkened structure in black is the substrac blt-m6y1) eb u-q*qkte and is bound at the active site.

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

The equipment below can be used to s)6b.qhip p-pcrkh hg(ilq+7 le- :a)n tudy the effect of temperature on the activity of the enzyme amylpbl q6p7 n gec))-( hpk.ralihiq-+: hase.



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 (bs74 6jdmofk substrates to catalyze rea f m(ds476obkjctions?
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 catalysed9o 8zec:lftm5a mr*n) reactions can be measured.

  How does denaturation wz; ty6vuz4.ufyb6xk*5 3vn)1jvj jvchange the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statem w58xwzx5m t-zmz,rw l).o.b rents are true?) wwwzz85m.trm.ro -, lxb 5zx
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 e/3- f;ffmy2pn lt2hehr.dt8p ctotherms that have fluct;f8tp /.tldyh2en-2 rphfm3 fuating body temperatures?

  A metabolic pathway that converts threonine to the end-product tk /-srpcs:2he / ))(sqduyuhisoleucine consists of five reactions. Threo )s /kd-h( /ts)2rhy:ucuqpesnine 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 incrqm3 gd z9 vik9v,y.mu.easing pH on the rate of an enzymatic reaction. What ism ui,yz vvd39.m9qg k. occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an*sfsoy t6-x 2nko m .5ud;b*xh enzymatic reaction. mhoyb txd s; kxu5f*s.*n26o-What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts th37p ax4*bsz5xg9x xq nreonine 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 iyou* vtc rp5./g 4dv4sts activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (*vy d 4ovcgs5up4t/r .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 the following is the best wayp onea5p1 q sq+/k9.bi to keep enzymes active for aiq p9bes. n/+5qka1op longer period of time?

  Which of the following describes somni mt 6,v3yqv+;hbt70 dl2bnye types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to r( 2mxn-t* xop,oy/opz d/ju3a elease peptides in the stomach. A study was carried out to dxpj/dz (y- 3 omu,txop*a no/2etermine 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 reaction ofq 0c0ud :zfr)6b pn99:vjhcx b an enzyme with 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 the reactions. The curve marked A coincides with the activitfdnj6vbz x90u 90b:cc: r )qphy 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 ro2l vtxpms5/3)n8d d;ct+yu lvot into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the vs +xp3ld)lc m8t2yd u;vn/5tturnip 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. 3(aeue7 hcp j1ud wh(:Inhibitors to the enzyme HMG- CoA reductase can lower the production of cho(3ea:h1wpdu u 7(ehjclesterol.


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 denaturv alirs)b-2dr;2l1k z ation?
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 cuo816 cmphck7xibg k7,, l o0ylassroom and were given an experiment which demonstrated the effect of temp67ko7kh0cgy ucipm8,,o lbx 1erature 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 effe,/v1lb, igi4fqph5n2 b8 gxdo ct of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriatopihq 1dgfv2b4 n/x, i5 b,gl8e dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (7y;f: p y2lzal5oe gcrn5,9jiBg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactalyap52ry :5z9lefog ;nc , 7ijse 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 with mnx+j9-55dnm, miljqth ( n io8yr;e* ealaria. Describe how anti-malarial drugs are being discovered wi ex9mh;(jq8 t* i+no e,lrm-i5jn y5dnth 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+zj9o/ mjwfj 3 affects the rate of reaction. + 3z fwmj9j/jo
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 reactionsxsd vry 5q/bzm.-2. ff. Which type(s) of metabolic reactionyd f .5sr-vbm q2x/fz.s are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the ratev5es ih2o*cx uir/3d 2 of enzyme catalyzed reactions can be measure oescvuiid2235r/hx* d.
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 chem) v,53 n-1*bkzg1 erwwp lciucical reactions, given one example of each type of reactc1eg3vp *l -ukz,wb1)cwr in5 ion.
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.