Which of the following macromolecbw+/cl8p g.ul5 gb2ux ules describe a typical enzyme?

  What type of reaction is photosynthe.cj 1kjc,p;t5ufhxk v*i. om1sis?

  What is the substrate for the enzyme lactase?r 6i wxk8mkf*;y(gb esv(1 yb.n.1jh+ t.qqeq

  Which of the following stagbnui*w5yx i 63es of cellular respiration takes place in the cytoplasm? 35ywbi*n6iu x

  Which of the following would not be useful in determining the rate of an e *a.3voygo 1oynzyme-catalyzed reav1 .gyo*o3yo action?

  Which of the following processes may be,,bvkfc:-y hwxev, *9hextg2 u c(a0g described as catabolism?

  Which of the following statemyz;elx1;hk: *qevg kg fm; lk 85w7ud:ents is best depicted by the figure below?

  Which statement about enzymes is2nx7a 6xh dpytr g7vh :1o )mygfp4-:g not true?

  Which of the following graphs best illustrates the r icng4k,08q0mxwa1t5es 2 .kk2brgepelationship between temperature and the activity of enzyme8nap1r4xb k5qt0 2mg0k,kes i eg2 .cws such as lipase?

1.Sketch a graph to show ho blq8 ixd5o+:nw increasing concentrations of substrate affect enzyme activitoq: i5bd8nl x+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 evc25+sm c9/z cooa6ireactions. A diagram outlining the Calvin cycle is shown bel/ c+9cmooczeiav s56 2ow.

The image below shows the catalytic site of an enzyme. The substrate is l;49cb7h ia zushown in black ai9lazc bh7u4; nd 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 4 iev0 m *oan/,shd:fg9epbu) the enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reacm 4daheepn,s0iuobv) g:/* f9 tions.

  Which of the following describes the role of inhibitors in k20x,w swab pb-0 etb)enzyme-catalysed reac t0as0k2,-bw) xew pbbtions?

  Which of the following correctly describes photosynthesis or respiaejezqkcf9 3;g4)qilr*i8gc tl q771sam( r -ration?

Many enzymatic reactions hap3*e lw/-hwbxv8 vdiv 6pen as pathways involving multiple steps and multiple enzywwe x d*63 8v-/vivhblmes.

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

  Which of the following best describes the inhibre3p 2u(b,1 9yjrf7j u:sr*ibygto 6sitor in the image below?

  Which of the following statemenbvgf+v*,q aex ws/t3(ts are true regarding regulation by end-product inhibiti3b*sg+e (av tfwv,qx/ on?
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 opqy (lu. 0es/j 6ltcap 7b:l*sf the lysozyme enzyme. The darkened str0yp7.ua b /l t6j:sc*qs(l lepucture 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 ofkccy8avr25qt r y*i4. temperature on the activity of the enzyme *25.y 4iq rv 8yraccktamylase.



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 +t ;t1ep jnqc3describes how enzymes interact with substrates to catalyze t3qn1t; pj ce+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 catalysed reactions canwg07-sf/lx77va j 6bwv w)let be measured.

  How does denaturation change the pro;f no*n*y7tw8h u958mvicf,eu n ozi3 perties of an enzyme?

  Enzymes play a role in caz6v1-xuag* t ltalysing reactions. Which of the following statements are trtv6 za-xu1 *lgue?
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 endotherms from ectotherms th -0w flusfe3t4at have fluctuatiftw e0-4fs3u lng body temperatures?

  A metabolic pathway that lj( pwxe 7p 3t23on4zyconverts threonine to the end-product isoleucine consists of five rea3po(l47e23jy n wtpx zctions. Threonine is 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 increasing pH on the ra81( hmsiohie ba.3 k)bte of an enzymatic reaction. What3 iaihob(8)e1bhs.km is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substjvfn z4 x8igr4w:ha +.rate concentration on an enzymatic reaction. What could be+x:ijf4hw 84vn zarg. the independent and dependent variables in this experiment?

  The diagram shows the pa*sdiv ik4j gh(mn c y.4+7w8ntthway 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 on a matrix and its activity wacsfzt;.2w2nedv x:cf 0vs 13as compared with that of a free enzyme in solution. The graph svs:ev fcxd.;ctsz3fa 0n21w 2hows 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. Wmft((0. kdnh y m7srd5hich of the following is the best way to keep enzymes active for a longer p7rd (m5k(sn0 m. yftdheriod of time?

  Which of the following describes some types of t )usfcu*(y f9zgs66f extracellular enzymes?

  The enzyme pepsin hydr:jm 7fbu oi 98)5lp+1ksgtfox olyses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing subst5kb ix t1+gsfl8:)opm79 ofj urate 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 showszy3g*b l6+n6.v yel tfj25npc the rate of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently t*z6+gly25yn.enb jcfp v6l 3to 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 a turnip root into small ku h 8o w6dwc 2xcpmp+)go+:*vcubes. 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 the liquid extract was stored in a test tube at room temperature. w+pv mw8xoh): ok6+dg2 upcc*


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 t-x/6k 6 n+w5 sdibmejath9b;to the enzyme HMG- CoA reductase can lower the production6k6biaw+5xd/-bth9est; m j n 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 art hf o7oa:)6jqu)k2afbd(t *ze 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 w -r/sfxfeyjk8 ra hyf.7m61 6classroom and were given an experiment which demonstrated the effect of temperature on a catabolic rew6 mef6js8-/7x.rfa fy1ky hraction.
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 effic a p/pprp dvd2w1alf;,/exz8h ed80x0iency of lactase activity is tested. Which is an appropriat /xdh0d01elaw/vpx 8zp2d fp,p rea ;8e dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg4k*koo l ua85h10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial l h8*ku4o5oal kactase 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 malawd.g8;zle acebw* q3 9i*ops- ria. Describe how anti-malarial drugs are being obps.qw8ei cg dal9w* ;ez- *3discovered 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 th)/, lv ;,we9;bvur vbktf.h obe rate of reaction.w,lvv;/b)bobef,9kv thr . u;
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 mixa c h;9rzz8i(jkz: cc44u k:etabolic reactions. Which type(s) of metabolic reactions are condensation re8:xz9h4 ucajzc4k: z (kcii r;actions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions uxod(- emxhdwd9 oxnm// * w om2i5*h1can be measure/2nh/io *( meu d h5xdmxoxw-o9*1wdmd.
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 exqg gl.( zfj:cp8* a9e:j3pke* tslpy /tracellular chemical reactions, given one examplf*8j g .e qz9 p pjet(c:kays3g/lp:*le 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.