Which of the following macromolecules9j0z,tz*l(b 3wwf)a -lr srls describe a typical enzyme?

  What type of reaction is photosynthesiwuc:ce ( cp75+agt/aux f(6fh s?

  What is the substrate f dew jeo x2-bl);9w,ghor the enzyme lactase?

  Which of the following stages of cellular respiration takes place ii4 oqe2gmet90c.k2 kxn the cytoplaek29 g 0ceo4.2mqkxtism?

  Which of the followingloh8 y.c p6y(;-2ir+elzauhy would not be useful in determining the rate of an enzyme-catalyzed reiey6 -y+zh cu.pal2;8 roy(hlaction?

  Which of the following processes may be described as (yu1naj6 gfquql ;:n6k5f k 6x/ldg7qy +6hmvcatabolism?

  Which of the following statements is best depih+8 d 6u+r :+9lvbpnlaiamdtpdhu) /k.7m3 gqcted by the figure below?

  Which statement about enzymes is not zc.ntpya 0. l2p:a2h ptrue?

  Which of the following graphs best illus vgtja2lc+uj e//1j r;trates the relationship between temperature and the activity of enzyme/r;2/+uljte jc1j gavs such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affeat:4yxrao l2 ) ayc/ :ggvy+u*ct enzyme : 4l/ytgaovu+ y)2*ga y:crxa 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 outlihh-vn6l7sw)95dofsh fj k8o .ning the Calh65whl7jh.s 9 osn o8kf-)vfdvin cycle is shown below.

The image below shows the j7o4/bgj oqb9o53 sracatalytic site of an enzyme. The substrate is shown in black and is bound to the active si54g jbso7b9/ 3joaoqr te.





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 descrf43zfw ncf3r* iptions of the enzyme catalysed metabolic pathways shown below? Lez3f fr 34f*wcntters represent various products of individual reactions.

  Which of the following describes the rom 0,xr3 1lx8.p(ix5mp3 l(gdkyu 2spob nly,qle of inhibitors in enzyme-catalysed reactiukxp 2sxpl qy, roi ll0ypnb(gmx , 3d(581m.3ons?

  Which of the following correctly describes photosynthesis or respjplmhs2im /25gp4e0i iration?

Many enzymatic reactions happen as pathways involving multiple steps and multi0yin ; n0k(yopple enzymynyo0p(; k in0es.

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

  Which of the following best describes the inhibitor 3uzy(mrq5uv9k)951j 5 7psol z 5eq7c marijv in the image below?

  Which of the following statements are true regarding regulation by ;xs8sukf ayz 95uo,:b(5w jcoend-product inhkuowo s(5 :fcz ;9b,5ay jux8sibition?
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 lyspl0ubnz 5bhzgq n5 un+zk)0iovjv 9.m44.wr-ozyme enzyme. The darkened structure in black is the substrate and is bound at the active i lz4vpubhgu0q 0vzm)..nr-zw5 n 94 on+j5bksite.

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

The equipment below can be used to study the effect of temperature onus8 n :t pz+zrc *jr28h8rj/xo the activity of the enzyme+88rtrz hj:rpscjx 2oz8 n/u* 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 statementsxziz)xw4gua463xi d- describes how enzymes interact with substrates to -azi4u6z 4w)3x xgxidcatalyze reactions?
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 reactions can be measv 0a4:+) is*q/4cvy fnqzmvjd ured.

  How does denaturation chacvcse-x 2mq(:0 dqi.q nge the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following sta7 nd*mx7mktae.6dj 6gtements are trnek677 ajmx.*6d tgdm ue?
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 t(wl4 1t )vwge ymwyejqfoa3a;, t9,x8hat separates mammals or endotherms from ectotherms that have fluctuat aq9y8t1w(tyvw emegaj;o x,)l,w 3f4ing body temperatures?

  A metabolic pathway that converts threonine to the end-pr;:7dg45 cwn af kktaa*tu0 hl3oduct isoleucine consists of five reactions. Threonine is converted to v;7 tka:nua345glk0d ftcha* warious 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 increasing pH on the rate of an enzymati- b0cbihmzlp2/0hx j */ occ7rc reaction. What is occ0cirbh b0/ cpx72j-l c*zoh m/urring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzyma5o5 5 jq*z ehaqy0b3bi,gpv1stic reaction. What could be the independent and dependent variables in ty i5*gzjeph a5o1 3qvbq,0b5shis experiment?

  The diagram shows the pathway that convertba z0;e obfu1 ;pdc.h5s 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 2wvj4sc*b4 k2 baow* knel5s 7its activity was compared with that of a free e7vb5* cs bk4j2*4awn2s lwek onzyme 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. o vh dtkb; v2+ao70t5oWhich of the following is the best way to keep enzymes active for a longer period of timk5hovtao7;d+obv2 t0 e?

  Which of the following describes some types of extracell jtxg 3g 4;,refu3-dik5)sfdls ek r*6ular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides i6h p9le6ikm:kn the stomach. A study was carried out to determine the effect of increasing substrate concentrate6 69kk:ihlp mion 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 increasing subflzlw(x9j0zub262 p 1k rn9f gstrate concentration. Similar concentrations of chemicals A, B, C and D wg( f09pn22 lz1b9xu6rjf l zwkere 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 turnip root into small 8-n;wofzl gr):pdux :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 exu)rzp d -lwo;::f8gnxtract 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 show90grtgpl d:p9-6 -nf p4;plwbni8rcv n below. Inhibitors to the enzyme HMG- CoA reductase can lower the produc ptpl i-f:bwln 0g9c648vnrp 9-dpgr;tion 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 in,:c2 kqm5ns afvolved 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 classroom and weu me-u; c889ten c9lbere given an experiment which demonstrated the effect of temperature t n9 8;le8cu-ue9bem con 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 efficienl.,kzn+qsu( r cy of lactase activity is tested. Which is an appropriate dependentq+(sun zkr., l variable for this experiment?

  A study has been conduch+53s4l.dqbjkvr;j pi+ pp s ;ted 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 to hs+vj q3p ij.;pl;bdk+p54sr 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 treat9p( jzv2lqor)//hwoasbg u +3ing patients with malaria. Describe how anti-malarial drugs are be)spwurbo39j //aoq+(gv zlh2ing 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 aja4d by5 3e-nng ; ouz,snvx-.n enzyme affects the rate of reaction. n5 3jbd-;uso-nyv gn a,4ez.x
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 p,n3 xj7 my epdgzc(11broken down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensat(,xn1 g7czydmej 1pp3 ion reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions capi*rx0:)qeg su+ck)i bso * m:n be measured. :ru im)s)bc*e* p xo:qsi 0g+k
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 chemica+-4(r 2h1f wu-v-f yh kn fq3kdzkx5ozl reactions, given one example of each type of rean 1yo -2v5hd4khrfzk-x fqw-k +f3z u(ction.
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.