Which of the following macromolecules describe a typic3gf.o20 qyeg jal enzyme?

  What type of reaction is photosynthesis?dvo+k3)c/ b is*r nd2qam4 s6l q5*gem

  What is the substrate for the enz ,fk yb:1iiq50lljz p.yme lactase?

  Which of the followingqy )vv9unm ,g7aph.v8 stages of cellular respiration takes place in the cytoplah7.qp y ,89um g)vvvnasm?

  Which of the following wou9z*8ja(dh3.qenlmoq o2zsobp*/3 3pn 9tq cold not be useful in determining the rate of an enzyme-cz / m3*qnb(89a q3soopd*l.q oz 9 no2p3ehtjcatalyzed reaction?

  Which of the following processes may be described as catabolisma/u6wg edvnj(5 /- zvk?

  Which of the following statemen jgu9 i+ou1-mjts is best depicted by the figure below?

  Which statement about enzymesr.4 ygvmp wr,8 is not true?

  Which of the following graphs best illucdc; ,ibjm 9j u29hdd.strates the relationship between temperature and the activity of enzymem9cu9c;d,i jdjb .h d2s such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affe4m egukd9 )* brsnyw fv71w28die9*h rct enzyme ac24kd hbgn)d 1 vrsfw*98mwuei 9er7*ytivity.
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 d+ d4dyk: g*yhpfa fs:2iy 2pq-iagram outlining the Calvinhyy +g: i2kpds*2:f 4a fp-ydq cycle is shown below.

The image below shows x gedspx4z z06 q9,rj.the catalytic site of an enzyme. The substrate is shown in black and .gr6 zedz jxs0qx94,p 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 s ariu gdmj 8+;hk.;n 27gw:fdof the enzyme catalysed metabolic pathways shown below? Letters represej;7kfw8da+ hdru m; sgi2n:.gnt various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-cataly5oq.wl6ot u o:sed reacwt:5lo o ouq.6tions?

  Which of the following correctly describes photosynthesfx6h k c.en9,eis or respiration?

Many enzymatic reactions eaak2rrh*,)gd qistqeq ;xb+q1p ;77 happen as pathways involving multiple steps and multiple en; sa,t qg)2*7;xe7d+kbqi1 qeah rprqzymes.

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

  Which of the following best describes the inhibitotdn*bq +kwq,zcs /x,578 szzqr in the image below?

  Which of the following statements are true regarding 2zke5 8z aowk;regulation by end-product inhibiti;ak8ozk5ze2 w on?
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 u7d ra9bnn;k.ucture of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at th. k rba9nd7;une active site.

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

The equipment below can be used to study the effect of temo:o-;ar)u9 i kd/n pikgpb8x 5perature on the activity of the enzy9 ;ip5kug- d :noro)8 kpxia/bme 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 den)6ag*26 jyzaced ;qqscribes how enzymes interact with substrates to catalyze reactions?eqnq6 )z2djc y;aa6 *g
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 enzym nf0aagdi t) vlr t3ib96+7*lue catalysed reactions can be measured.

  How does denaturation change the properties of an s f,drbhm :dc27/*pz benzyme?

  Enzymes play a role in catalysia /t+cn tan2)hng reactions. Which of the following statements are t c aatn+ht/)2nrue?
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 ec kw*qwi)d2vh9t4m5. uiqa ( kytotherms that have fluctu*d v yt).kum4kiaqhi2w5w q(9ating body temperatures?

  A metabolic pathway that convert27p4gzdn i7nl s threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequdnnz7 l 4i7pg2entially 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 nig l ut/mxz4902:v3 v u3gur jyu5)qreffect of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase la/ ig zm0uv523x )r vy:4uutqgrju n39lbelled section X in the graph?

  An experiment tests the effect of c v1cld ,lt)c+wbr:t;d7hzc*o hanging substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this;) t,*wzcb 7 +v1ldcd: rhclto experiment?

  The diagram shows the pathway that converts threonine to iw z lg6 9p.*ztqu+hx4lsoleucine.



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 itplto 1x (c97c );ytlmws activity was compared with that of a free enzyme in soluc9otlpc;wtxm7 l1 y() tion. 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 dena6 5hmpn) t guh7zwn+l+tured. Which of the following is the best way to keep enzymes actitg+ 7l+unwhnz5p )hm6ve for a longer period of time?

  Which of the following describes some types of extrt7crc*bqof.9nl2j5v j. dz ;aacellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the sn ms6da,b 0mg8wq/5ib tomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity anm,b gdm06a5/b8 wi sqt 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 in1tkj.g p:p)fet*pt t( creasing 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 reactiof):g1tetp pjt k( *.ptns. 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 activit o 9eh68si fzni wro-ptm:/8s0y, a student cut a turnip root into small cubes. They measut/fn6si meiz8rhw: 9 o p0so-8red 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 s4 tq:e)rjfug; qp*:y shown below. Inhibitors to the enzyme HMG- CoA reductase can lowqyj:pqs:u e;t* r 4g)fer 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 invn egu/8,h xe0qolved 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 invests2es b-q1mts*:2uctz8p,t hiigating metabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reais1u pm ,t sz- 2et*tb:8sq2chction.
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 increasingsmsvv:+-3grnf*iqcl 8 0e sh* temperature on the efficiency of lactase activity is tested. Which is an gf* m es0c:8 l+q*hssvir-3n vappropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), angs/ u /yq-3yswalysing the effect of pH, temperature and glucose concentrau/s ysqy3w-/g tion, 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 tku(+mu6 k5;tm+myy9)o jd z amreating patients with malaria. Describe how anti-malarial drugs are being discoveumkkyo5+6mj;y+ d mz ()a m9tured 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 affew,3 l8e1 :g uzjgb,lxncts the rate of reactilzxlbnj egu1 w,,3 :g8on.
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 broi x-os1(uhrow , r*o8oken down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensio(8ro xor-uho,1 *ws ation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be mex nra3y .*dv(oasuredyxn(r a.v 3od*.
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 ;a+f1 sr+ sb)e+ayo sureactions, given one exampsar;+b 1y a+fsso+u )ele of 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.