Which of the following macromolecules describe a typical bw,r*,w1cl ipf+-kv f enzyme?

  What type of reaction is photosynthesis?kk94kneyc a h(ii*p.hve6pw)r 7-r6u

  What is the substrate for the enzy 5kjsfp7: bnx,a7+p amme lactase?

  Which of the following s9 dhukoeju jfyi-6ix;.28 5jqtages of cellular respiration takes place in the cytoplasm?9hku;io5uxy . q2 jif6ej j-8d

  Which of the following would not be usefu.g vs:r0urs0t m1n+t rl in determining the rate of an enzyme-catu:rtnmss+ 1 0r0tv.rgalyzed reaction?

  Which of the following processes maycucpdr(j 8ml xot93 2: be described as catabolism?

  Which of the following statements is beiggt v4yp an2m97r7u48jx0r*ym0 di ist depicted by the figure below?

  Which statement about enzymeex;03ov, . rqem *qh7uck 2xe8sd g/les is not true?

  Which of the following graphs best illustrates the relation + 10o lgcv3i/j1dlclxship between temperature and the activity of enzymvj 1/l+g icll3 doc0x1es such as lipase?

1.Sketch a graph to show hl.ci/ j23ion)v c)lmgow increasing concentrations of substrate affect enzyme activity. ml .)cl3oig 2nj/ )ivc
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is 4 cj/)o ge/t/jfeuss7a series of enzyme catalysed reactions. A diagram outlining the Calvin cycle is sho/s jsg7cf/ o 4ejt/)euwn below.

The image below shows the catalytic site of an enzyme. The substrate is shown z)d(j,6t3q an nakb7w in bk6d3nn)bj(aq7 , az twlack 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 descriptions of the enzyme catalysed metabolic pathways shown w8q f:;1bqclvqgqwtfc7u 20b4kv( : vbelow? Letters represent various products of individual reac4vvt 8b2 7bkqwcvu :g0ff qclqq1w( ;:tions.

  Which of the following describes the role q6o.t2e dfk+ uqjr9q1of inhibitors in enzyme-catalysed reactidfk qqe9 61qrt2 uo.+jons?

  Which of the following correcq vsbzux xp5g:goe4* r6.0sox (; c8evtly describes photosynthesis or respiration?

Many enzymatic reactions3obzt3 9iuv z1 happen as pathways involving multiple steps and multiple enzymes. 3zov zit3u9b1

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

  Which of the following bes44 i /y nbpae*aa:t1lmt describes the inhibitor in the image below?

  Which of the following statements are true regar ghmvd. nff ..e*h*nw+ding regulation by end-product inhibition? e f+dg.w. fn* hhmn*.v
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 structm wghg +cucz1,,bsl3n;m1t4 q6b ev6wure of the lysozyme enzyme. The darkened structure in black is the substrmshut3nbg1+qcz w v ewg,61 ;,lb4mc6ate 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 efps.fodbpdujj ad9 c k )+z6(.0fect of temperature on the activity of the)k.c.9 0os6+adpjz bud(p djf 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 enzouz.jpk:cw h,7. , pzrymes interact with substrates to catalyze reaction:z pkr u.oc,hw,.pj7zs?
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 can be m x07:gkaq 6fbpeasured.

  How does denaturation change the properties of an enzyb . e1gi2v2xxtme?

  Enzymes play a role in catalysing reactions. Which of the follfo y)tpsv9.*)l h,rn oowing statements anr o*tov.phs y )f)l,9re 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 ; iu+27sbkkuwthat separates mammals or endotherms from ectotherms that have b+u uk7w2ki;s fluctuating body temperatures?

  A metabolic pathway that converts threonine to theklrkgp 9u5p*)r t3we4 end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymesg4*petp5 wrkruk3 9l) 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 increas tnzf1ouc:+d8 ing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled secti tu1c+ 8zdo:fnon X in the graph?

  An experiment tests the effect of changing substrate concentration on an j+i,8ttdlr f4mj o-, uenzymatic reaction. What could be the independent and dependent variablesol,-jj df,m4r 8i tt+u in this experiment?

  The diagram shows the pathway that converts threonine to ix0rllroz;saj1 ke7m-2x0 f1 gka; d d2soleucine.



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 and7n89 wr 6rtbqs its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH ( rqs7wn t869rbx-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. Which of theyhtjs7..uteh0*7a u o following is the best way to keep enzymes active for a longer peri ash. uo0 .7t*uyhej7tod of time?

  Which of the following describes some types of extracellular enz ,pmne92 62rp5 u3eets du;anbymes?

  The enzyme pepsin hydrolyses protei qn3qrwws(d.i/ d1:rkc j,a u(ns to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a (rrj:w c1 /dd s(3qu.qan ik,wconstant 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 increasingfxpupmh 45;loq+ua w rgqa*wd mc9g)+r z00-/ 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 curvr5a+uz / wqm4dx); +lwch fm0qppg -gr9* o0uae 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(w w10l vos;ve fad1rj/8wf;p , a student cut a turnip root into small cubes. 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 liq/vlw f 8w(rpaj1dv; 1swfe0o;uid 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 g5at y8r4z3xjc 5-4 w3zaw xyhshown below. Inhibitors to the enzyme HMG- CoA reductase can lower tta4 5gxya z r4-w38hycj3xz5whe 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 dh nch)j95 hdnf7o9j *rcq f12lenaturation?
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 metabolxtwo)up pedh,;:97k n j(8viiic reactions in the classroom and were given an experimenu)p(79id ,xe kjhtp wi v;:no8t which demonstrated 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 iy.oj4ty; y7.xlc9lpc:ba c u 3,yxh- on the efficiency of lactase activity is tested. Which is an appropjccaoyt c3; ..47yl9 ipu,byxy-xlh: riate dependent variable for this experiment?

  A study has been conducte*0t yu94ow4zkw)t rxnd on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactx4*ko0u 9wywntt4 )z rose-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 tre9i5xr,*rw /k uud tx931mcexyating patients with malaria. Describe how anti-er9*d13tckxu9,mwyr i / u x5xmalarial drugs are 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 the concentration of h;xk4s4)t sni.yh, lman enzyme affects the rate of reacym ;kss)n,x ht4.h4li tion.
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 m ajl1.:hf38zp 4osazjetabolic reactions. Which type(s) of metabolic reactions are condensation reac .hjz: s1ofapj4az3l8 tions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme cat,:uok 4 t cfoi6cui-wv)91 ytwalyzed reactions can be measured. y-6u)ww1iv 9f c4itkc,u: oot
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 an its5q020b ivvd extracellular chemical reactions, given one example of0iq0 2it v5svb 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.