Which of the following macromolecules descga qok/,zg c9,ribe a typical enzyme?

  What type of reaction is photosynt0jsf50 f40kx yq;s prwhesis?

  What is the substrate for the enzyme lactar5 k(qxvhfb 06se?

  Which of the following stages of cellular respirawo o w 56rbj3 ixool4d9-3vfc5tion takes place in the cytoplasm? o-rof335co w9ijvlx5 6d 4bwo

  Which of the following would not be useful in .x7- *mywb zuh jot8c8determining the rate of an enzyme-catal.yb8m o8t-ux 7 zh*jwcyzed reaction?

  Which of the following processes may +:m9y)vynp lv9n)lnby v(9 yn be described as catabolism?

  Which of the following statements is bes sj :j3zdfqu-0t depicted by the figure below?

  Which statement aboutx ic5s /af lu70b1waa+ enzymes is not true?

  Which of the following graphs best illustrates t( krjlvaz m3any q 4735wi;rek7(3ognhe relationship between temperature and the aj5a3g kaovn3zn li4q3r7w7 k(em; yr(ctivity of enzymes such as lipase?

1.Sketch a graph to show h*h(93j gw vxvatm0f:w4zjy* t ow increasing concentrations of substrate affect enzyme activity49 attj(*:wjyg xhvz*vw0 fm3.
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.0u lpb yfw3ceg +:*ri0 A diagram outlining the Calvi0p0 r* b+:lfueyi3 gwcn cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown il7 +0 sq56cnuo dl q*1ybmgn.gn black and is bound to t l0n6bs.*gy5d gl1+ qc nmq7ouhe 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 catalye60+ hq2xkn z8p -2ziqr aezi)sed metabolic pathways shown below? Letters represen8hee2ik za6irqn-q x z+)pz02t various products of individual reactions.

  Which of the following d f/7 * yllq-9ez-eidqlescribes the role of inhibitors in enzyme-catalysed reacli ed9q*l -e7q/zyf -ltions?

  Which of the following correctly descrlt170f txfi)y ibes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving yv,n 0/yoyb/b multiple steps and multiple v/ob ,0nyby/y enzymes.

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

  Which of the following besteyt+. 2 vqgzx.a*.qxi describes the inhibitor in the image below?

  Which of the following statements are true regarding regulation by j5mpus ao g5,+end-product inhibition5,g5+mjup oas?
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 aym3-q , epb)eu,xf3hg;n( qiof the lysozyme enzyme. The darkened structure ihe;fe),3gmqyap( q ,n3- ixub n 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 temkl sfyp/v.k) (perature on the activity of f( /kyk)slpv .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 in,s*ygh(.l yr w ;e2lowp51j()p ec+vy j*mocnteract with substrates to catalyze reacty)eg.h**p,21r (nyvm;pojl( ocw 5ewl+ yj scions?
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 ream-l9 exa3jhz 6jxr5w;ctions can be measured.

  How does denaturation change the properties of a3v3lw *6zst nsn enzyme?

  Enzymes play a role in catalysinl,kf5)w vn./zthl +hg g reactions. Which of the following statements are h/hz.v )k tfwll5g+ n,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 endoth 0naxyi5 vti )um2k1/xerms from ectotherms that have fluctuating body tem mitny 5i1k2/v0xxa)uperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine p0 6u)mqyofcfg3m(atw. t 1m)consists of five reactions. Threonine is converted to various intec om60pmu(yt .3f fmta))gw1qrmediate 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 enzibx e/;sh 1na k-6-haeymatic reaction. What is oe-ke6s;xi /a- 1habhn ccurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on ft eonub, t ry)2.el:(an enzymatic reaction. What could be the independent and dependent variables i ln( :2 )ey,.bturfeton this experiment?

  The diagram shows the pathwa*bo; ixcn4cs5 y 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 o7,p:w prjq r.fn a matrix and its activity was compared with that of a free enzyme in sol.,p:r7fqw prj ution. 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 denatur ru*.i o8wn+ 3*hx+cz9fdrzdwed. Which of the following is the best way to kee+hrwi d9* nx+orfwdc .z u*38zp enzymes active for a longer period of time?

  Which of the following descdskv ;32j ;kdu:s7a lb9l)zwnribes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the st 6ejno hk ++s4.xyg)le2 9oanuomach. A study was carried out tol+46 jk9 oh+ gsux.2 e)aonnye determine the effect 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 subvvf9br rg4/h+ ngy- 6jstrate concentration. Similar concentrations of chemicals A, B, C and D were added independervnyv +4jf 9rhb-g/g6 ntly 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 aud 5hy s:t3zg: 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 th 5h:dszy t3:uge 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- CoA reductnvi: u3 nz6*aaase can lower the production of cholestenzu* anaiv6:3 rol.


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 involved in dent i8tf a5u* 4uuce7u z:/4ayphaturation?
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 were giv3 4.mlwf4ze3nj7a ht)x,cj unen an experiment which demonstrated the effect of te)4nzucfjtmjn 3 7wl. , xhae43mperature 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 temper2zcf ce0vk)ka/u .h6s+ xpzg0ature on the efficiency of lactase activity ispasxzkuf0ce.+) 2zkg 60v/ hc tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lacd7ja :2-evsjx tase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a com-j 2vjdsa7xe:mercial 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 newx,o8 )qv0xu du70xskt drugs for treating patients with malaria. Describe how anti-malarial drugs are v8tkux, dux0s x0oq)7being 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 x: a.7ml*rvcnof an enzyme affects the rate of reaction. rm*v:.xl7 cna
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 d7ma (1xtlev /qown or synthesized through metabolic reactions. Whiclx ma7e v/tq(1h type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enn9i6z s(kikqu4o69 scvd8wguiq85x1 zyme catalyzed reactions can be measured.k9dn6vqoux 416cs gis 8 95uk 8iwiz(q
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 gd7rsg,hy8x3reactions, given one example,d 8gs3 rxg7hy 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.