Which of the following macromolecules describe a typicacwxqb fu oy7;6be ./wfw 78p*d1* hrpyl enzyme?

  What type of reaction,cac2ym0 pz t77 dqqx6 is photosynthesis?

  What is the substrate for the enzyme lacta,9o+ gdc (p *(lhwguvyse?

  Which of the following stages of cellular respiration takes place in the cyto r9kv.vei: 3+imci 5qsplam9:ic5sv qe +iriv. 3ksm?

  Which of the following would not be useful in *d(e 3n hs yo2pcl;w zqhh2k(6determining the rate of an enzyme-ca*pc w6d;2henq3 (2yzhhkso (l talyzed reaction?

  Which of the following processesx r1r(jd f+iu.e yj.ct-:n:j4vohwz8 may be described as catabolism?

  Which of the following statp bzskm;5+8j4a ma7g nements is best depicted by the figure below?

  Which statement about enzymes is not truel 6b0u+tuef,n, 1 wjsu?

  Which of the following graphs best illustrates the relh(wo/. rwdnz 0gzpr;:ationship between temperature and the activity of ;:pgz.r0nr (w d/wo zhenzymes such as lipase?

1.Sketch a graph to 9:.;kp5ivjde 0qbu pfn2lt/b show how increasing concentrations of substrate affect enzyme alq/utne fj9:2 k; dv.p50pbibctivity.
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 outlinina33 i6kw2kn ujg the Calvin cycle is sh3 kauj6 ni23wkown below.

The image below shows the cata26gg5ua5h z+xb +fcaklytic site of an enzyme. The substrate is shown in 2 ab h+5au zgckgfx56+black 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 descrw ez1 a4t4lpx-iptions of the enzyme catalysed metabolic pathways shown below? Letters represent various produtle x-a4 z41wpcts of individual reactions.

  Which of the following describes the role of in79dicrprzn*a d2u 3.phibitors in enzyme-catalysed reactrpuzp n2r9 37.*dac idions?

  Which of the following correctly describes photosynthesis or respip)hns3a p-cj (ration?

Many enzymatic reactions happen 4g+e;e6vaypo as pathways involving multiple steps and multiple en6 e4;yvpo+a egzymes.

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

  Which of the following best describes the inhibiaupgo7 3iinzmb;1*75bse m (y tor in the image below?

  Which of the following statements3 xg9-ip2.nj:td lg eq are true regarding regulation by end-product inhibitioxde-j g .np:qg i92l3tn?
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. The dc7 eu hcouo9 1-dw658jtm5 odxarkened structuree7x oh8tdo1c9w6u udo5c mj5- 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 jhbna e, 3 u2 *9w08adv7v 0xxpxjgy5yof temperature on the activity of the e a dw*nh0y2gvx yu bv 93p0xjx5,e78janzyme 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 stat8)zs. g9-1rgy zxgjd* qmppx 7ements describes how enzymes interact with substrates to catalyze re mxyzzsg*gp9gp- 7q)18 jd.xr actions?
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 enzymez5v2spi 3l q.zg 8abg j1lr7)t catalysed reactions can be measured.

  How does denaturation change the properties;ow. p*.9h e( g8dbgjbl)ndhd of an enzyme?

  Enzymes play a role in catalysing reactio5sh ue1kk eo+ n8pg*3pns. Which of the following statements are5k 8o epn*pegh1+su3 k 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 e*c/ xtdfx(*ta6 w9l6bt xnh6kndotherms from ectotherms that have fluctuating body t9fhca*ntt6wt 6 */b xxk 6xd(lemperatures?

  A metabolic pathway that convertjx-y6:uwc j htj7.i h9s threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is concx6. j7hywjj- :iht9u verted 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 of4 mvk 7a+lams8 an enzymatic reaction. What is occurring duringmsm+a v4 lka87 the phase labelled section X in the graph?

  An experiment tests the effc(kb 7 y+mgqle5n mfrg-;wmg45-cyt7ect of changing substrate concentration on an enzymat 7gkl ;4w( ecqmc7tf5n-y5rymmg -+gbic reaction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isole gi.kn24ai*v zaw:cy 3ucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobci)2hl zc4 cvuy4:g6yt30)n(m vev6i plhk8i ilized on a matrix and its activity was compared with that of a free enzyme inpyihhy) 68l(vi4: n 4lvc3) ict u2mg0z 6evck 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. Whichtuom 2+mc:,5/wx afwt of the following is the best way to keep enzymes active for a longer period of timetmw,t/fmao2 +5 u:xcw?

  Which of the following describes 1ws() +/osb5dpluuv o some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release pepusgx 3 ghikl3 on4*b+8k3z)uktides in the stomach. A study was carried out to determine the effect of increasing subskzl3+)k*xgiko3ub hs4u gn3 8trate 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 in/ snoi. qk.11;p/ ycol(stjvtcreasing 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 coincidec1syqo1n/ os; /ltj(vt.pi. k s 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 3iy8f9 98oxz nnhlmr -turnip root into small cubes. They measured approximately 5 g in a weighing dis 3o hf-nixm8nz99ryl8h, added 50 ml water and used a 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 enzyme HMG- CoA:,r (u8- nqwfhul).l *zlgy jb reductase cann:) uqug *- ryzlw.ljh,8bf(l 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 are involved in mx:o re;mj+v(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 were qs;/9 (j ckbnrgiven an experiment which demonstrr9qs bn k/;jc(ated 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 e dal.ygb:ov(- :45jd 7bxph8v8.*nr cgfqdqsffect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variabl8r:gvlc 8qx y( p.-abv5b *g:o7q ddf4sj.hdn e for this experiment?

  A study has been conducted onbd07*gl *)wcah)lfxo the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as ighbw* 7 ) fc)*lx0dlaot 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 treating bi . lm9:vwz4va,k (yapatients with malaria. Describe how anti-malarial drugs aazlk4 ib9.m v,vy:(awre 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 theah- o:t*;7z z*a tmefw concentration of an enzyme affects the rate of reactite- a*o:z*wh m;z7tf aon.
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:7tvn(g ktxp.1u*pt p through metabolic reactions. Which t(k: pvpg t17t*xptu.nype(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways thb fgz73.fu(z6iy,ou9 q yizn 5e rate of enzyme catalyzed reactions can be measurfqy u5ii, u.z7n9 3fo(6bygzz ed.
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 rvw-v/dcnx3dp 0 zn m:l 6*.boseactions, given one exampsvb* wd3 m pnzx/v d0-on:.l6cle 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.