Which of the following macromolecules describe a typical enzf 4,h-j 6asy5ee0lt zeyme?

  What type of reaction is p0*(lwivzz p3e-)avz6r kb 3opigl) 3 photosynthesis?

  What is the substrate for t3*-(te su- z utx-pcjuhe enzyme lactase?

  Which of the following stages of cellular respiration takes place innf4+eij ko1ked k w;8vjn7i6 5 the cytoplasm? 8 k+ k; 6en54dvfnio1iw kjj7e

  Which of the following would not be useful in deter5wq vv et *twmj3(t2r2mining the rate of an enzyme-cat(vq rejvt*w2t 3w5t2 malyzed reaction?

  Which of the following pro* ko;vtn.qs 4dcesses may be described as catabolism?

  Which of the following statewxxw vk:1xl))ments is best depicted by the figure below?

  Which statement about enzymes is not tko. )fk; wemy,rr pmu2ngk9ezb41 ,y;rue?

  Which of the following graphs bese *g d+mmsye-4t illustrates the relationship between temperature *ms+d-y meg 4eand the activity of enzymes such as lipase?

1.Sketch a graph to show how incr f8 wpxeot+:ryf 0v-z8easing concentrations of substrate affect enzyme activ:+8e0x y-frov 8wtpf zity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalys)djk0 935nwvye (am tted reactions. A diagram outlining the C59n m kvt3)yd(w0etjaalvin cycle is shown below.

The image below shows the catalytic s/s0d5pk+belh x0a b z s54aj0rite of an enzyme. The substrate is shown in black and is bound to bk hbaz4 5x5r pss0+de jl/00athe 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 showztc 5;xp8t62h)uroth n below? Letters represent various products of individu )ut tzh5;xh82 6tpocral reactions.

  Which of the following describes the role of inhi0hj0er)t od,ybitors in enzyme-catalysed reacti)h0 yte j0dor,ons?

  Which of the following cotqdmf(+7 8 d)z)fya wcrrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pasa862q mb dp4tvj61rmthways involving multiple steps and multiple enzym pmtb48q a2dj s6vm61res.

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

  Which of the following best describes the inhibitor in the +e:f: utlt6+fcgqmg*e lumz78vs7+ aimage below?

  Which of the following statement1umc*s9m- y qcf6j(o ms are true regarding regulation by end-product inhmc 1sq-omf96c *m(ujyibition?
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 hc0 5gs *tasc,t 8 v)+qmv;.j2qtsgsethe structure of the lysozyme enzyme. The darkened strucms aje g;sct+q 850tvg shs ),qcv*t2.ture in black is the 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 temperature on the ac*q-l wq)/ sknstivity of the enzyme amylasq s-lws*nk)q /e.



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 enzymes0t0qvaw 2ow0dj y-2lh interact with substrates to- qhlwwtvj0 2y20ado0 catalyze 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 reagj1 5c,*fschm 6v +z *mw:hrw w6h2gfdctions can be measured.

  How does denaturation change th +x0p pt*lds2te properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stateme --lsak ln,gm /e(+dkrbi+h*ints are ts,dmnkl -i +*hela+/k- (gibr rue?
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 tg:rqc 1ae63j ihat hava:ir6g1j3 ecq e fluctuating body temperatures?

  A metabolic pathway that converts thry g*)r.nl)jb(6 zmxlbeonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate produclg6b bljn. y z*rxm)()ts 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 enzymatic1 du6om7hsbdfar :xs 3lf,.y xz(;r.d reaction. What is occurring during the.d;.dz fos7rx 1sfd u,( h6:alxb3mry phase labelled section X in the graph?

  An experiment tests the effect ik9b9i z(3sgd5bs2m h1me3df gd82 qpof changing substrate concentration on an enzymatic reaction.bfedhi(pmds29 3z895k m3gg s21 biqd What could be the independent and dependent variables in this experiment?

  The diagram shows the pa;td15ul2ysp c thway 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 actukk ,pxu50 s2bivity was compared with that of a free enzyme in solution. The graph shows the relative enzysx ub0 pkku,52me 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 denature bzn -5k2*iadnd. Which of the following is the best way to keep eni5d 2kba*nzn -zymes active for a longer period of time?

  Which of the following de hs1;t 2sms yzt3kq(/zkp oq1:a, d9ycscribes some types of extracellular enzymes?

  The enzyme pepsin hydrolx9 do .ym4qq6w3hdmg 8yses proteins to release peptides in the stomach. A study was carried out to determine the effeqmd84od3my w xg.h6q9 ct 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 of an enzyme with increasing subst* pko hxiqvrrf-8. i5 4s.ef8prate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monitored for each qk.v e. s-r8for*8i p5i4xhpfof 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 -(pf-fuap)uq7jhu o/ 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 p- hq ua-)fpjfo7/(uuand 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. )l s0x*mcpewh7u+ ksw 9) 8sauv(f bd0vw8(lj Inhibitors to the enzyme HMG- CoA reductase can lower the production of chplm*cw0)v ((uxs +fj)u8sbwev098 ahw lk 7 dsolesterol.


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,e(trucdgu :g x.n+b6b7hk 2zs4 n3xv are 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 me ly5+;nld,v30) ham8xj qlrqptabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic3lnqj0 +)m;laphx 8 d qr,vyl5 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 tebnsvz(2e6cl2 id. :zv mperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable fov. 6:bi c 2el(dzzvsn2r this experiment?

  A study has been conducted on the activity of a specih .rz4w89wxh eb l.t:0jmja-)xi imi3/euu9cfic lactase (Bg10), analysing the effect of pH, tempb hxiej 9iharw.c 3j.zi) e4-0 ml8/uw9x :muterature and glucose concentration, 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 treatinm;:fgq 9r i/ z*oyjug ;; ym23wrtdqs4g patients with malaria. Describe how antrryg tq : dzg;;;*2 jymiwfsu/9o4 mq3i-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 concentrfv l fhjl4wp 2xs 9kk(103t5xdation of an enzyme affects the rate of reaction.p5w1 xkxth ksl4f30vd 9lj(2f
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 dowfejh(p )k*z, cn or synthesized through metabolic reactions. Which type(s) j (,pk)eczhf*of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different waa:w:/z-;fa y woave 0b4d-bfiys the rate of enzyme catalyzed reactions can be measured. fazabw-o aey;4/bvwif-:0 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 andss74,j lvo q ml+z qsug82kv18 extracellular chemical reactions, given one example s7 l us,1kvj2oq+mzlv8g qs 48of 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.