Which of the following macromoleculeszq /jb8qy,h225ha0upj g. blu describe a typical enzyme?

  What type of reaction is photosy4li8wh:qg6qwizg 23u2w jq1t h(sl2 knthesis?

  What is the substrate for the enzy(;5cwgz or 0e1gbd. k3w,pqjjf s(r .yme lactase?

  Which of the following stages of cellular respiration takes place in thegt,rt8;w0mag f9y v j, cytopla;80tjwg9yafr t,mvg,sm?

  Which of the following would not be useful in determining the rate of an enzyme-w 8oqbh3en.0 iqwv3 a-cativ03h83we.qnowba- q alyzed reaction?

  Which of the following processes may be describedb;6u(3n+snqa2c bpi z5g9 uy axeu2n) as catabolism?

  Which of the following statements is best depicted by thms m;c+:;,*yapeu9mhg ua xt.e figure below?

  Which statement about enzymes is not true?5 aj x(vzg)v2y

  Which of the following graphs best illustrates the relationship between*zwc p44n(:t(j wf55fnq lc wp temperature and the activity of enzymes such as lipasez(5(j nl* 5wcqt4cpn4w ffw:p?

1.Sketch a graph to show how increasing concentrations of substrate affo/3v)ts.xlfy t1 muy+ ect enzyme activityfyx .t oumvs)1lt+3/y.
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 diagraixx,:dqc+k6 ra(t t2bt p5bgb3 hlt34m outlining the Calvin cycleq3hg cax5ttpt+2r3 xlbbi(d:t 4,6 bk is shown below.

The image below shows the catalytic site of an enzyme. The substrate is )9cm eed,bvr( 20vzm qd *(znzshown in black and is bz 9 2dvvee0*z,zb(dn c)m qmr(ound 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 descripti4mxkip,p-o ,:ts:m u fons of the enzyme catalysed metabolic pathways shown below? Letters represent variouss-4pmo pkxmf: u:,it , products of individual reactions.

  Which of the following describes the rezdnu .l ku.5b g3k34x(fw (0x knoc,wtc/.ebole of inhibitors in enzyme-catalysed reactions?(f5z cwgkk 3lc3bx./ eu4n(, tn wo..0xduebk

  Which of the following correctly describes photosynthesi kbia831q+aa u u kzbd+m1d)t8s or respiration?

Many enzymatic reactions happen as pao;g9oa gyj:k +thways involving multiple steps and multiple enzyma+:oo y;jkg g9es.

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

  Which of the following best describes the in --.g/+*p.kbximht ced/mdy ahibitor in the image below?

  Which of the following statements are true regarding regulation by end-lah -7ws60xdcproduct inhibitional0ws-dchx 76 ?
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 h2r.,kvt:ps )i dmh+x the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the active site. )t :xr vpd+,. mishh2k

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

The equipment below can be used to study the effect of temperature xk,c 2psu+;/rn8 eikyon the activity of the enzyr;2 /ksx8y n+ip,ceu kme 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 e.mazts()bl 4r nzymes interact with substrates to catalyze reacr(t.z) lams4b tions?
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 uqfb4qlc,n 4boo w*-2p4pyp/ reactions can be measured.

  How does denaturation change the properti,/6js t giyk3+ty i 6qf bknlo4oim671es of an enzyme?

  Enzymes play a role in catalysing reactions. W ms1.ag;l p3n.pxei6z hich of the following statements are trmag;1. sile3 xnzp6p. ue?
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 mamma n0kv2uql)yiy a+cal5 gi z/wi.-i(3sls or endotherms from ectotherms that have fluctuating bo asily5zqi (nl)kcg3ui-w+. iv02a /ydy temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucinuobe -2r:xy o cf7sfj2l87tp) e consists of five reactions. Threonine is bf f)y27 o28rxto u jse-cpl7:converted to various intermediate 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 inc nbt3n(1iv 6q vpj +zoip*+y5kreasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the graii+tp 6+1k(3*qj ypnnzv vo5 bph?

  An experiment tests the effect of changing substrate concentration on an enct6(py p9pc-7b qg.v -3k x6xaxkn)nlzymatic react(6 xx va7-nk6xtn3kp 9-b)yq p pcl.gcion. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threo0l.n di:qnw:ci55 cgk f;w3lhnine 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 activity was compared witd -5xp +kbggt 6eo2.ndh that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-ax+dbopk2n.gdxtg 6e 5-is).



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. Which of the following is m.get rxd*w(cu 6m,za /c8 :ssthe best way to keep enrmztw,x cas*c8gsm e 6/.ud :(zymes active for a longer period of time?

  Which of the following describes some types o9cv) vces .8tuf extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptkuh(,i ;h5fcytd /.msoz6 / meides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a siu;m/(. ey5,td 6khzh/ocmfconstant 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 sq1 w g2io.t m:v+;japwpf/b*reaction of an enzyme with 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 re;1f+m2 g :qa*w ppvbts.w/joiactions. 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, :4. j2xmlytrvw 10+ hakllr2c:: dyp va student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml wtc+km2r1wdv : 2jhpl.ylary lv :0:x4 ater 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. Inhibito p 5*62 twq3qztd6-r0grwpb fars to the enzyme HMG- CoA reductase can lower the producti g bq-6zrw0fw*tq3 2dpp6art5on 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 denaturation?tp 1e(uxfk,a.6z /qysur-p4y
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 cla4 *anhsqt6d ,qssroom and were given an experiment which demonstrated the effect of temperat6ah4sqq* n,td ure 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 effec-xne w7 x(b5rzt of increasing temperature on the efficiency of lactase actbx r(znw57 xe-ivity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a sph 7:g;mn) yleo4rjc -(ambw8c ecific lactase (Bg10), analysing the effect of pH, temperature and glucose conc8 m7mjlgboc-c y e:4r h)wan;(entration, 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 treatik4gq fnkvhs++ st+5w 9ng patients with malaria. Describe how anti-malarial drugs are beiksst nw4+q gfv+k59+ hng 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 r6al28yn bxu.*nzh t h6ate of reaction. unl6nhtab 8.xh2zy*6
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 ba/ l uj9xt28mzroken down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation reactajl8 u/ xmt92zions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reaction f;dz;vk s7epth,(/ bns can be measurt,ke zd; shn;f bp/v(7ed.
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 chemi5pqig x)8m)no m7rd1ulqul ;*cal reactions, given one example of gpluqlum7x51;* irn ) q)do m8each 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.