Which of the following macromolecules describe a typical emd ;sgpf(q ,p7nzyme?

  What type of reaction is photw +e2ab1dpv2 ;qj+m ehosynthesis?

  What is the substrate for then b0(4;ajztoz enzyme lactase?

  Which of the following stages of cellular respmgea0vwe *.;dhip d58u2(y iriration takes place in the cytoplaed i.(e*vp 20uwy irmhg;d8 5asm?

  Which of the following would no jy x uy,k-aa0,;q3dhqt be useful in determining the rate of an enzyme-catalyzed reacaqdx yjq -,y;uk,0ah3 tion?

  Which of the following processes may be described as catabolism*osp f cbla7 ;:, p8czo ig)7zo1+ydmy?

  Which of the following statement vw9vt2by1uq2s is best depicted by the figure below?

  Which statement about (cb4 7kigju ox+c*+rj l8xo4yenzymes is not true?

  Which of the following graphs cq19t7 lps h,ebest illustrates the relationship between temperature and the 7qchtse9 1lp, activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of /qvc;gnn lw0 7substrate affect enzyme activ7n/ l;vcw0gqn ity.
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 diagxo1 zp:3t2eusweh k/ e;kn.. yram outlining the Calvin cycle ze/. 3e oxps kekntyuhw:; .12is shown below.

The image below shows the catalytic site of an enzyme. The xao3/.o cci3hxt qquy ,6* eu0substrate is shown in black and is bound to to6aexq.x/uy 03,quo3 *icc hthe 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 descriptionsi1lep f0fa im+ (u3f/m of the enzyme catalysed metabolic pathways shown below? Letters represent 0i f e 1(l/3um+ffampivarious products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed rdzwyo )f*c*ffp20o z+eacti* 0wffopcfz+y2* z) odons?

  Which of the following c4gu bs9 5dye g*0g1f9poz.p*b cpzhwnt7ua6 5orrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways 9lhz8)b d 0 r;-jizfrf9fj *xminvolving multiple steps and multiplef)0 lz89fm jr ib*frx9-djz ;h enzymes.

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

  Which of the following best de :b hgzm)4lbn-n* .ettb)2kfoscribes the inhibitor in the image below?

  Which of the following statemebudq f4qby1 ,*bt7ot:nts are true regarding regulation by end-product inhibition? tbuq,od* :b q74b ty1f
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 lygg :ua- ,i m+,-cppwyn0 k)umesozyme enzyme. The darkened structure in black is the substrate and is boun g -k+m-nuc)ymie: p p0,uw,gad at the active site.

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

The equipment below can beuosea/-l5 vh ; used to study the effect of temperature on the activits;hle ouv- 5/ay of the enzyme 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 subuh)g6y1aj +tl strates to catalyze reac+j1yugal)t 6 htions?
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 catalyseds nx im ixtstn7wjcg/89- z5u+p8p (0w reactions can be measured.

  How does denaturation change the properties of an nmf- kxg hb)yl .+h.v:enzyme?

  Enzymes play a role in catalysing reactions. Which of td3 7(b0 tzvohvhe following statements are(hdtov3bz 7 v0 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 endotherms from ectotherms tu95k2 l ;hk w, sb gb4) opx(orzsjgojmp8+c.4hat have fluctuating body temperatur.om rl wo bjo5sx+ u)pbgp4cg8 ;z(sk9 42hk,jes?

  A metabolic pathway that converts threonine to the end-product isoleucine con 5iv-w.y ebc9:rn e.en4euv q,sists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymenv . .eey: iune-4ewb9v rq,5cs 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 m -elbnd7:, 44vcxs/t;c sue)p2-+dnwtehjwrate of an enzymatic reaction. What uj:2ss7th4) w mlxw-+c/vn c;b pe-d e ,4ntedis occurring during the phase labelled section X in the graph?

  An experiment tests the efiq mzi.(w::sufect of changing substrate concentration on an enzymatic reaction. What could be the iiz(ui:sm:.w qndependent and dependent variables in this experiment?

  The diagram shows the pathwayw shua(0;em0 r 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 matrix and its activity ms g9q0dpf- g85xb/dlwas compared with that of a free enzyme in solution. The graph shows the relativd8 -l5gdqgxs fpm/09 be 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 the following is the best way th.xi0 mhn. fq0o keep enzymes active for qifh0m 0.nx.h a longer period of time?

  Which of the following describes some typesmpwm3bc4yvn komi352 2 gm 0ls28msp1 of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomac3u srv u cml*, ji+0zp5gp0knp;ri98 ch. A study was carried out to determine the effect of increasing suv cz0 lskuju *9m+80nrp c5gipir,;p3 bstrate 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 tru /x :. f*qkmnxm:0kuhfg0y:he rate of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added indep *xm/x.kfh0: fk mgyuq u:0nr:endently 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 turnip root into sm5rjqch:pcz1( 38uyiy all cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and usc y1i 8 hj3zcryp5:uq(ed 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. Inhibitors to the enzyme HMG- Cor h zj-3a2ot;xA reductase can lower the production of cholesterol.;x j3rh2 -toaz


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 involvelk 4fiko 71t*qd 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 the classroom5.c wi2y7v i8mugv ic+3ttb 8b and were given an experiment which demonstrated the effect of temperatgtv+35 8.mtb 8 ciu2v cbii7ywure 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 bpzt b).12:7r8npf5eb-cz(psq sso teffect of increasing temperature on the efficiency of lactase activity is tested. Which is an approppzn2cbsb87)zsopt 5 .b tp:efs(1q r-riate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lac z44*m9a otfbltase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produc9lam 4t* fzob4e 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 malar 0zmw6x amuip+akaqr- c39a09 ia. Describe how anti-malarial drugs are being discovered with new technologies.apxazrm k-99m 3iq0au cwa+ 60
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 mfzrzpt3s20pa 1n+x *reactmsr3pnt x*p f+1z0z2aion.
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 throug t fkt3zefv 29ndht3*1h metabolic reactions. Which type(s) of metabolic reactiofvh2fz1 9*3tettn k 3dns are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of ype bg*g.an7m+j 8p1 uenzyme catalyzed reactions can be measugbnp y8e* a7g1mj+p.ured.
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 chemicaljto ooo t4*:l; reactions, given one example of each type of lt oot4o :;o*jreaction.
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.