Which of the following macromolecules describe a typic d j:;i0awwehp:tw(4ne xm dml0 c/i)-al enzyme?

  What type of reaction is photosynmii rx-d2h2j6mjc )h6thesis?

  What is the substrate zhxnxvn8fr5 -: j;l2hfor the enzyme lactase?

  Which of the following stages of cellular respiration takes pl8./t-ugmhv mom .z.m9llqd( sace in the cytoplasm? o(t..v9l dmg/su8m. mh zqm-l

  Which of the following would not be useful -4)v y v-r4)l s-e8lfiswcbqyin determining the rate of an enzyme-catalyzed 4e-vsls8-qy -v) l iy)brfw4c reaction?

  Which of the following processes may be described anq ;fe.zb1z a j+v4+p kxk/tx0s catabolism?

  Which of the following1e:o rx8pai2 c statements is best depicted by the figure below?

  Which statement abouz3h n9xy a2a0 rf)b8z+ 6rzilvt enzymes is not true?

  Which of the following graphs best illustrates the relationna6* ui:/lh(sgkz( nm4v2m rhship between temperature anhau z6rhsm(/*4lvg( ik2:n n md the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect enzy a.u uo+u;oilro945 dame o; 4ol9draa.uo5u ui+ activity.
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 diagram outlino(1ihx 0ktl gv,zns 7r5kc 7-eing ,(0nc57-ek7rktoz1 hv xglsithe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate t 8och1,ta+ yt4c; gtnis shown in black andtt1h t cc+y ;n4ga8o,t 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 descriptions of the enzyme catalysed metabolic pathways shown33cneep im xbogr1+7) .4dcmn below? Letters represent various pro ncpbde.x71omc)rg 3+4n e 3miducts of individual reactions.

  Which of the following describes the rolx+d1 bxys qqo*wme.67 p71 bhse of inhibitors in enzyme-catalysed reac xx s11eys6hq m *+.bo7bd7qpwtions?

  Which of the following correctly describes photo;htg sdxe0/r9zft wdg436t6n.b h8u vsynthesis or respiration?

Many enzymatic reactions happentc16n 1:hhq j,wd: dwd as pathways involving multiple steps and multiple q d c::1wjt,n hw1dhd6enzymes.

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

  Which of the following best describes tht)klx;b t)4nke inhibitor in the image below?

  Which of the followiidq:b .i*vhq ,h aq)mcahz)0.ng statements are true regarding regulation by end-product inhibitio*,.b ):ihahq hvmc )ai dqz0q.n?
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 enex(08t. oxwf xm1v 8umzyme. The darkened structure in black is fvxt 0.eo(xu 8m1xw8mthe substrate 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 study the effect of temperaturk r*k.n1+ ,h czgqwkhbtk ;)txiz.26ie on the activity of the enzyme amylase*x1qkn zr i h kkhzgb6;ttc kiw)..,2+.



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 sqf+plqyuru+2zb *8dg1w 4fn 0ubstrates to catalyze reactions?gr4+w 0y8l2uu+ qndq* zpffb 1
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 ro;gp(8/ ck9bb: tby imeactions can be measured.

  How does denaturatioa84qeqcb y 5bak)ah 9-n change the properties of an enzyme?

  Enzymes play a role iw6/ffa 3cf: c9ml s)em4c; tten catalysing reactions. Which of the following statements are true?ef sm) cwaf4;/: 6tt9flecm3 c
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 mamma 1emh6 b;jecsow:qwqcynl/.ay6y/g f ;8b2b2ls or endotherms from ectotherms that have fluctuating body tem;2jbnwb hc/1 . ;bmcqeyl6agqf y:6 so82w/yeperatures?

  A metabolic pathway that converts threonine to the end-productv1qj 2 )7 aicr .txos4/qwrf5k isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme in thoiqrak.w c jq 74r5fvx1)2 /ste 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 the6jiyx 3j u*.ym rate of an enzymatic reaction. What is occurring during the phase labelled section X in th 6 u*3j.ijyxmye graph?

  An experiment tests the effect of changing substrate concentration ol0e*yyi6gxm v(m +( jpj/r6ca n an enzymatic reaction. What could be the independent and dependera(*l (e06/j6y jc vigmx+pm ynt variables in this experiment?

  The diagram shows the pm9yvo-cpnr l4+ qf*1pathway that 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 immobilized on a matrixy1 alg 0425wznq+s *x. ezsols and its activity was compared with that of a free .s+s eo1xlw*q2 40zsnyl5gazenzyme 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 thh mb9t1rguliv)l:458gftcoafmv 8 juf3 ,i+9e following is the best way to keep enzymes active for a longer period98:mgmloa)5 ji+ f4,gv8th fr1ufcbt uil3v9 of time?

  Which of the following describes some typwulg kz52q 2c44dyav )k 5cg7ves of extracellular enzymes?

  The enzyme pepsin hydrolysesrpp kn3q0, o2i proteins to release peptides in the stomach. A study was carried out to determine the effect ofi2,k0por nqp3 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 bl) ekx 2 zany0wp4a0+j86hrkincreasing substrate concentration.za kba2+ljpkr h80 0) xyew46n 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 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 ccuv r4tv5 o-f)cw37d; f+wwt out 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 in a test tube at room tempercfv c;d tfo 3uovw7-ww)+r5t4ature.


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. Inhi fegh7emx+;m ;bitors to the enzyme HMG- CoA reductase can lower the production mf;x;7h ee+m gof 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 3v l*rfr-7jpsare 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 metabolic reactions in the4;ibf:-hj / e5xqupgd classroom and were given an experiment whic54bj uf-:xqd / p;higeh demonstrated 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 efficiency of lac at y)-c+nn9rh/l +xjgtase activity is tested. Which isht9n)x+c+l /njy -a rg an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analyc ys2u25,wep vsing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lacta5p2vuy s e,2cwse 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 ne owlar,st cm 9ix/. ,v;lv0p6nw drugs for treating patients with malaria. D0xmlv.9/ l; nvaw6 csr,toi,pescribe how anti-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 )buuandfrq 7q7er-42ul5c q8zl*kg/rate of react- f7 rlcaedln*8524bq 7gzu/qruk) uq ion.
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 metabol9tpgeam a 0h0zs g/ heir/:0h*ic reactions. Which type(s) of metabolic reacph0shg09ee h/ 0 m*a zi:atg/rtions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cat odc)w2e*rt6 e9t .8cymbm:v zalyzed reactions can be measury)beccmm o2* 98z.v d:twte6red.
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 extracellulaoa8s1,ea3b lw r chemical reactions, given one example of eac b1a l,aesow38h 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.