Which of the following macromolecules desgxx y5 (go0q2xg7d2g5 jc gze(cribe a typical enzyme?

  What type of reaction is photosynthesis?e4,/r m+vxsg a

  What is the substrate for th )s5l+dlnuy-zi1 oj hf8gd, w1e enzyme lactase?

  Which of the following stages of cellular 3kkk;7/ipn mu respiration takes place in the cytoplasm? 7k3p i/ knumk;

  Which of the following would not be useful in determining the rate ofo 2mu9s qddo+pu z,-e) an enzyme-catalyzed rez+u qo d,s-pu)edmo 92action?

  Which of the following processes may be described as catabolism)wd4 p(d4itqx5vgw +s ?

  Which of the following statements is beyx6e. we2/ f8ps4y csrst depicted by the figure below?

  Which statement about enzymes is not true?qwdx-qins6,*lou 1+ y

  Which of the following graphs best illustrates the relationship between temperata,g9lh/c/ 8umkeg w -pure and the activity of enzymes such as lipakp9wgam8c /h le/, -guse?

1.Sketch a graph to show how in4uxwuj5d xh)5dh*ib 43o* 0cyip uuzf ;4xo0 ucreasing concentrations of substrate affect enzyme acx5u4i)0ipzob4wohd h503 uxf4; *ycu u j *duxtivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enj.c1(vfrbvt (zyme catalysed reactions. A diagram outlining the Calvin cycle is shown below( c.1(fbvjtvr .

The image below shows the cataly;e2a f2tu 6g kp*ee5obtic site of an enzyme. The substrate is shown in e f22akpb6 ;t5eg*ueoblack and 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 of the enz(/cg;tji k4w uw8 wr) l(kz)wpyme catalysed metabolic pathways shown below? Letteur wwli /kw))jg8(;w k(4tpzcrs represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed (9 avfpdv-9itreactio v 99(ptf-idavns?

  Which of the following correctly describes photosy9gooc-rk8 u6knthesis or respiration?

Many enzymatic reactions haoxjlycijg/w,4 r )/i3ppen as pathways involving multiple steps and multipl/,3 wo cjyij4)l ri/xge enzymes.

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

  Which of the following best describes the inhibitor in the imahdtt2t2ym( 8p:v )m k ytr;yk8ge below?

  Which of the following statements ay p5)q2l5l2e)bqwlqr*h )t ts re true regarding regulation by end-product inhplq2 b)e5q*r)t thwl)2y s ql5ibition?
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 lysozyme enzyme. Then0y):rs:for bn(yoq3s1wq* z darkened structure in black is the substrate z:n y*wronbqy:qr)0(o1 s sf3and is bound at the active site.

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

The equipment below c jl z:9sstfbrut5v587gm84je an be used to study the effect of temperature on the activity of the enzj89r4:7ejg8t 55bsm luft vs zyme 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 enzyg 8, )z6hsob cit8t/lames interact with substrates to catalyze rea)s ti, gahoc lzt/886bctions?
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 catalyseggzg +ofz9;i2 x5:h7a; w pay*atpmi0d reactions can be measured.

  How does denaturation change the pr;flkk07dpq.cus-h1k 6z:wj ui 5e ey-operties of an enzyme?

  Enzymes play a role in catalysing reactions,m. 1gasc nryb q 9cs69y6zs/q. Which of the following statements ayy9c6ncqgs6m/1rs b , 9za.s qre 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 separatel9 qp( vfts;+(;:x4jgj wtinw s mammals or endotherms from ectotherms that have fluctuating body fjt+g;nw94 vl ((;xwsiqj t:ptemperatures?

  A metabolic pathway that converts threonine to the end-product isoleucinea g9n0h- zx/ul consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzymnzauxh0- lg 9/e 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 enzymatia8 ask;0x(52fn37o fy gzt7l3 bzotitc reaction. Wx t5a0f8b27tkgfsyi z73z( o;al n3 tohat is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing ski450-j ib lvfi0iml/ubstrate concentration on an enzymatic reaction. What could be the independent and dependent variablbljlv 0i5kii-40mf /i es in this experiment?

  The diagram shows the pathway that converts threonine to gsk5ilph,j4p)v g jn0e ;n93w 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 and7rwcj.+vg ,vwpr74j.- v .om:i0 dw /omhoms z its activity was compared with that of 4jcsv0.og.z wohvr opi d+wv mr,j.w7-mm7:/ a free enzyme 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. W0z eqt iv./j2.;synjp hich of the following is the best way to keep enzymes actinj0 zip/;e tqvyj.2.s ve for a longer period of time?

  Which of the following describesflt ,e 59/qbx4kg)eo y some types of extracellular enzymes?

  The enzyme pepsin hydrolyses prots,sl j41h7as eeins to release peptides in the stomach. A study was carried out to determine the effec, 4 jes1h7aslst 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 q+yng r bf fj3hbe37x g*mv;6gjrpq,7h 95z :jwith increasing 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 reactions. The curve marked A coincides with the activitxrfpghfg;qvh z6,*nmjg y9j5:73q +ber jb73 y of the enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity,j fqlecr)z cc;8) bb vg+1.o:k a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used abc;becvrqokl)+ .gj1fz 8)c : 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 x)msw7d5l ,7*tkj.j vpuz 8 ftenzyme HMG- CoA reductasexvuwz lm7t7j ,.ftd)8ps *k5j can lower 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 arhsr):7) oy rwc-aa pl73q :zrke 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 metabolic reactions in the clasam )n9 d(7hjotsroom and were given an experiment which demonstrated the effect a(t7nh9mdo j)of temperature 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 effectbr:) jxwqre1f qp4 yx6)7 gtt/ of increasing temperature on the efficiency of lactase activity is test/)7e) 6xqt x1 prqfrgw4b:ty jed. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specifigyms/db,.g4d.ana 4 sc lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commerci sb,dyn4/dgam4 .sa.gal 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 treating patients with m fg g)vqju/7c1aw5nn9alaria. Describe57f)aw1jn uc9 qgnv/g how anti-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 concentration of an enzyme affects the rate of reachwlw-) xfqx u.pt q)w35x :v:ltion.wtqv 3p:w.)h llx)xwx f-uq5:
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 through metabolic reactions. Whicy9 hb5*jf szi0h typiy zfb9*s0 h5je(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can xk j;+fmgd)q mq8 *h6rbe measurejrh;d m68+g*kq ) xqfmd.
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 bf+u4c fb9 1dcintracellular and extracellular chemical reactions, given one example of each type ofbc 4dfc+9fb u1 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.