Which of the following macromolecule oej+b4gy ylk/ht1d*0s describe a typical enzyme?

  What type of reactione,*uff eb) c9k- iifexnx9w 84woj(m/ is photosynthesis?

  What is the substrate for the enzyme lactas,s mn1 -dk.wcte?

  Which of the following stages of c3 im4fn- k 6n:qrnc;n56fy:xwyqm ;zaellular respiration takes place in the cytoplasm? 46qn:mn5rfc: z knw;n;6ayf3mq -xyi

  Which of the following would no3y narx-1y-dy.hml 4gt be useful in determining the rate of an enzyme-catalyzed reaction?la 4h dyyy.-r-nxmg 31

  Which of the following processes may be described as catabolism?., unzw gq:ci8

  Which of the following statements is best depicted by the figures:q8qy3goi: dfur2b 2vb rz 7/ below?

  Which statement about enzd g+,ysf5 ho*gymes is not true?

  Which of the following graphs best illustrates the relationship between temper:t6d;r- a8 p lskjxf5 6-vdttyature and the activity of enzymes sa6ldjdxr -5t-ty: k;86fs t vpuch as lipase?

1.Sketch a graph to show how iq-.bj*da j x)qi4 sj)uncreasing concentrations of substrate affect enzyme activity.* d4qjxa q).j-us)jbi
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a serie 2s5hsvrv8plq xn ,/-ys of enzyme catalysed reactions. A diagram outlining the Calvin cycle isl2vn pr,hqsys5-8x v/ shown below.

The image below shows tbsn +cd6jbue 6wt.5ia9 pl;6j he catalytic site of an enzyme. The substrate is shown in black .nibe5jp cj+u 6d;a69bwl 6 stand 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 deseufoz)p3v c/v6 )slm8criptions of the enzyme catalysed metabolic pathways shown below? Letters represent various products usv)/z63 mpcvo )fl8e of individual reactions.

  Which of the following describes the role of inhibitq,: gksg-l:kh ors in enzyme-catalysed reaction:lk,g:g -skqhs?

  Which of the following correctly describes photosynthesis or 15yrp,24i(g(re lgid(s usf w sxc8*hrespiration?

Many enzymatic react n8/o-v hojrd h:)ys2i j6*gqjions happen as pathways involving multiple steps and multiple enzyhnor hg6qji8/)jo j:2s- d*y vmes.

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

  Which of the following best describes the in 1 eipqpuw*kcque.(y8w0: *xchibitor in the image below?

  Which of the following statements are true regarding regulation by end-product i;p1qt cqf4aqv uixv 6t3a.i7.nhvxitv qpt cqa7.uf.4q316ai;ibition?
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. Twm- 45a d ydudoz/d)hqw3pmt ehc+o(, q )id*/he darkened structure in black is the substratmddqo+ 4*p- m(it)w/q, how3zda)yc duehd5/e 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 activiq,.zf .wko 9 sci 55xhhh0x/dwty of the enzy5ixfxh 0c dz h5 wq.,s9khwo/.me 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 substratd dvj9-hn kg)*r08vua5ey6j bes5 9nkdrvae)ujb jd-vh86g* 0y to 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 catalndskp, ) :ajp*ysed reactions can be measured.

  How does denaturation change the proper 80jxzid4+wleties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statemenv5;z xef xrudf3;64al ts are f x 64f3euda l;rvzx5;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 mam8nif9y bfv8p49kp- h imals or endotherms from ectotherms that have fluctuating body temp vy98fiknpih 4b-8p 9feratures?

  A metabolic pathway that converts threonine to ti9 ;6tx g 55wnjwzlp0whe end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentialllw9 iwn65wj;tp gx0 z5y 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 a gf 6qpt.b wg-:o1e7/jbbj1pfn enzymatic reaction. What is occurring during the phase labelled sewg-f7ebbo/ 6:1t.1qjf bppjg ction X in the graph?

  An experiment tests the effect of changing substea3y9((,dsnl det *s crate concentration on an enzymatic reaction. What could be the indepee( csla ntse,dyd9*( 3ndent and dependent variables in this experiment?

  The diagram shows the pathway that converts th;5 wp/p ntkqx)reonine 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 itfzpc8rusw : x+ 0icl23*w(sif s activity was compared with that of a free enzyme in solution. The graph shows tiw3zcf*x2pscu(0lw i8 rf+ s:he 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 arej 6qfp+v4uyi7ms 2+**wzlob e easily denatured. Which of the following is the best way to yvi*z2qp*s 4o muw+ b7j6f+ elkeep enzymes active for a longer period of time?

  Which of the following describes 3ck2zg*ai)tk0be0 ,+ m y cahusome types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release pep ceyfz -* v0(t9yu-apstides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on*a- ty yz v(pcue-9sf0 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 incdawk/;6 kfna +reasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and /;wfa+k6 n kdathe 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 pka ,n1 5pv2pmtv7t29jfb0msinto small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize tafs0 v 5j1np ,vt pm2bkm9t72phe 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 +;6 inkwe,bo sqoocu7l5, f 4yis shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the ps;f,5 +4yo kolien ,c wu6bo7qroduction 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 involved in 5 xa9: jdpi21tv;4jqr7 rn5cx urg jq*kbzi83denaturation?
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 classr oqj x;,5g- my6ru)e(mcy +btroom and were given an experiment which demo;6g+cq t(mbuy -)xrryo,jem5nstrated the effect 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 effect of increasing temperature on the ef4eyq3d); n leks+lh(uficiency of lactase activity is tested. Which is an appropriate dependent variy qe;3n) e4+hd klul(sable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), anacub6uf o*qoe y8 ivrjbg1 jov+k1*7:)lysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial l8oo+jkvf1r: )j 7q*c yiub1uv*o6begactase 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 malarpxu/pj( 5rb(4* a1q wjpzq/ h 3slfds2ia. Describe how anti-malarial drugs are being dqs* l 5szj/ uq(jh2bp3fw(/da1p4rpxiscovered 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 enzyb) qa8o)3y4il:dsr kbme affects the rate of reactiadk 348i))sb yq:blroon.
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 reacti r) iqog h::b5q ldpx)k8.t6qrons. Which o l. q:i: bgtphqr5kx)d)r68q type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cwlf, )vpce/i9 (a* f6oele( nhg *sn/hatalyzed reactions can be measured*,( hf(s/n ) e*iegvfo6phwa9lce /nl .
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 reactions, givwrrw go;2 /u-ten one t; -wgowur 2/rexample 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.