Which of the following macromoleculew(x e ,vx ij)x4abbt*3s describe a typical enzyme?

  What type of reaction is photosm,om kp0d mzx bw+*sq,0u() dqynthesis?

  What is the substrate foraud h 4c.q se/k+x:n9f the enzyme lactase?

  Which of the following stages of cellular respiration takes place in 4c v1 z14gq3a ljyh. n5/ypdvcthe cytoplasm?gdqy/. 44pahyjz5cc1l v1 nv3

  Which of the following would not be useful in determ .n53rq( dozxsya rkxj,i28e *ining the rate of an enzyme-catalyzed reaction?k*r isq.2o5aj 3,(e x8yzrxn d

  Which of the following pb g-n fqeq- 2d,j:;fdvrocesses may be described as catabolism?

  Which of the following statements is best depicted by the figudulw,cga8 5p5d0+ gauefk y13re below?

  Which statement about enzymes is notvj07p w 0zdni+ pa0u0c/h)x 9nnfwoz( true?

  Which of the following graphs best illustrates the relationship betweens, a,ju:kcb y4 temperature and the activity of enzymes such as ,s u4: yackbj,lipase?

1.Sketch a graph to show how increasing concentrations of substrate afz q0zv7vw0b e:e4zu9gf qi+, jfect enzyme ac+ 4b97 vf0zz zvu:w0qjiegq,e tivity.
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 un),jzllpk8dlz 9*8ndiagram outlining the Calvin cycle is shown belozj u*l 8n)kd9l,8pnlzw.

The image below shows the catalytic site of an enzyme. The sgxg6b**rn ijw(9-xbi ubstrate is shown in bla6gijbix(9- gnr wx**b ck 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 de0voa vkr5gj w*ou5.u3scriptions of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reactiku v*5ua.oo 5 jw03gvrons.

  Which of the following describes the role of inhibitors in enzyme-catal,oxlry; isi b8y j5/(ovp:nu eqn:b7 *ysed reacs*q o8nxop i/ e rj7b:vuy:n;(,il5 ybtions?

  Which of the following correctly describes p 6g0 oxohws9wcjf,;f9uk (( zahotosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multi5;sn 7y5 9xdbvg;saluple steps and multiple enna9vsxl 5;5 dbgu ys;7zymes.

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

  Which of the following best describes the inhibitor in the imck/,,w2k cf tyage below?

  Which of the following statements are true regarding regulatxjiu t 6iipl0w0 2ak;qa25(p uion by end-product inhibitioxk2i25;u(wu lq6a ip 0t0aijpn?
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 structutl)289dgdx8n bmp , zjp*/jk ere of the lysozyme enzyme. The darkened structure in black is the substrate and is bound ap9k x z/ tg )d*8j,j8mpdbn2elt the active site.

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

The equipment below can be us wabmw;yj( n;lw .umr2o- (rt:o5zox 0ed to study the effect of temperature on the activityt w moo0z;yjw a;5r -l(m(nxouw2.:rb of the enzyme 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 int2(,y2ydk f9cvvdxus dm)d a63eract with substrates to catalyze reactiondf d,kc2yax ()u2m 9v 63dvydss?
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 catl0lzgg;g33lnom c 2 y-alysed reactions can be measured.

  How does denaturation cha uxl.:vvdppm, k9.s09czubc/ nge the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stateswko 7 j;/+d4 2c-wc*rywjexn ments are2c je*-x7orw wj;cnsw4d y /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 s()ql(hte gd0d eparates mammals or endotherms from ectotherms that 0gd)hl(et( qd have fluctuating body temperatures?

  A metabolic pathway that converts threonine to ti o2wg a05g0xzhe end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine bgz 2a0 o0xi5wgy 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 efy*o o qrtv 3of+6u)kipe-o j8)fect of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X inpe o*yu3t+v)i fkjoq- 8)oro6 the graph?

  An experiment tests the effect of changing substrk*yhn6coku ;sk,(t0xpk:gk p,mpy / .ate concentration on an enzymatic reaction. . ogx yk*ktpsyp( kc ,mkk;:n6u,0p/hWhat could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucine.26shd7e+ 3c6.b5ruk6kes ydfbmxp 2o



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 ak y(ofz 8r8di9nd its activity was compared with that of a free enzyme ii r88kfz(oyd 9n 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 easilyg3q114qb7e8yu ayclu;4ymmk +tay q; denatured. Which of the following is the best way to keep enzymes active for a longery4lqtb7q4q1 + a83;mamuu ecyykyg 1; period of time?

  Which of the following describes some types of extracellufj h+ 6t;p4eealar enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stcl obvuhf60:5h4q8 i tudy was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temp60h 8ouvlh t4:b5ic fqerature 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 increa0yjp j2oz)jg7sing 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 reajgpj o70y jz2)ctions. 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 activiri 9)ry;ms+g9c *rv5 cudlfy2 fc q-7dty, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighins7civml;rdfqgr2 -*r5 ) fcy 9u+cy9dg 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.


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 sxdojip1 h34t bu +c;t1hown below. Inhibitors to the enzyme HMG- CoA reductase c+c43b tu io;jdtpx11h an 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 invom u;o5 eco +uq;zzanh/qz q4-0lved 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 (e6r-lxpff+e metabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catar ep fl6x-(e+fbolic 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 efficiency of lqd lj . v1uj vzyt)woilso q:4p*8.0-wactase activity is tested. Which is an appropriate dependent variable for this q.wtzdi-1u:sj8lyj 4 0*o.vvpqwl o) experiment?

  A study has been conducted on the activity of a specific lact aq.rva.u:/vn3f z )uaew,vf(ase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it mzafvn:a f ).ua(v /vuqe,3wr .ay 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 continuousw7xdi-x iiq.uh t8*42bbewv : need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discoverev2itibqw7u h: 8wx. di4xb-* ed 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 rea)1ofg2 c siawr/zr0d/ ction.)1r/sdwc0 /i ao2fgzr
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.n7 )8v i 2akhunog of*i/f*w:;cfm q-p Which type(s) of metabolic reai u)8c7o:q/gnm;h*opkfw* 2 vfif-an ctions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different way9n 6lyze 4tou3emh r,z,-g:efs the rate of enzyme catalyzed reactions can be measured.f, m4y,eg ze96 tr e3nzolu-:h
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-jdj)ju g7p s2wlf1v- chemical reactions, given one example of eac-js7wgvjd1u 2-lj) pfh 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.