Which of the followikvhi9c u;03r t1m i8dcng macromolecules describe a typical enzyme?

  What type of reactio v 97 *bi.;n6 magmxbore,owv6n is photosynthesis?

  What is the substrate fhco5pm3vp v/* or the enzyme lactase?

  Which of the following stages of celludz8+l.b aucql.tw(8x -y bmmce+41a dlar respiration takes place in the cytoplasm? amdx m.czy+1ql8.l-ew 4(b+bc a8dtu

  Which of the following would not be useful in determining the rate of an enzyvt pw8dy u:qc 31rm0h1me-catalyzedp18 q31rm0v: wyudtch reaction?

  Which of the following processes may be described as cagc9pp,8laeb1 x .:gua tabolism?

  Which of the following statements is best k7jb94oz amb2 rbwq,) depicted by the figure below?

  Which statement about en53 9p*/jsokvlidd( mo zymes is not true?

  Which of the following graphs best illustrates the relationshnn j hy6y0z8(dhbc 4i0ip between temperature and the activity of enzyydb z8ci0n h4n0 yhj(6mes such as lipase?

1.Sketch a graph to show how increasing concentrations of subir5 h+ettyd b axn7544strate affect enzyme activity. ha+5xye4 ri4 tt d7bn5
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme cataly )dx+aye7hr ft;rb7w 5sed reactions. A diagram outlining the Cab+7 wa5tr ;dxe 7h)yfrlvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is (3nvs f6; a/sr 4 mh4zfxwx:7yulwqr(/pag( yshown in black and i (vhfmrn y4;r :wsgs/(zax 74(yfxlw6qa 3u p/s 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 descriptionsvwas:jt d8k9d-t v8h* of the enzyme catalysed metabolic pathways shown below? Letters represent variou8s-tvt k wdj*9v 8dah:s products of individual reactions.

  Which of the following describes the r wt6+2gy eio.34ou yorole of inhibitors in enzyme-catalysed reactiryge 3o.+wou 4yo2it6ons?

  Which of the following c eq3 rr,xc r1.2yf-jof)j0gzrorrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple stepspqa/nbn5xbctc e-ud 2,1i j;; and multiple enzymesdci t-n5aqcb1; 2/u;en xp, jb.

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

  Which of the following best describes the inhibitor inwgb ,u((oj 8)hua ztu* the image below?

  Which of the following statements are true regarding regulation by end-pr8bs+3t spf2cj oduct inhibitioncjfs+p t 3sb28?
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 enzyx d33vj4a sh8ume. The darkened structure in black is the substrate u4x3dav 8h3sjand is bound at the active site.

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

The equipment below can be used to s)qe,arg+i rbj u.b2 yl5 ta5,gtudy the effect of temperature on the activity of the enzyme amyl.lyg,tai+ j2bu a5bgqre )r ,5ase.



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 ij4l 1gg(ne)ws nteract with substrateswl j(n4 g)ges1 to catalyze 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 can be measured.c vi zdohj;;n(:a158r cee:sr

  How does denaturation change the properties of anjt; yh: mk v3a6d)gmc9xlm(0p enzyme?

  Enzymes play a role in catalysing reactions. Which of the following sta 325s3k.zzvbgm9nhqfs5 c /tetements afesb2mzz5g.h /nsct 3vq9k5 3 re 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 endotherms from ectoy.vsd *soy st-7ra (3ytherms that have fluctuating bso(t .dy a3ry*7 ssvy-ody temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine conr-shwts.te8 -gnf 8z) sists of five reactions. Threonine is converted to various intermediate products s)f .-s tg8hz8etw srn-equentially 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 rate of an enzymatic reacti b08+0 )cjiivjgprn5fji4y p+on. What is occurring during the phase labelled section X in the graphif)ygpjvr 0p8n50+jj4b iic +?

  An experiment tests the effect of changing substrate concentration ob06vip8 qrl36sks *v6zdx u n.n an enzymatic reaction. What could be the independent and d6qpu i*b03.v 8kdxssnrl 6v6zependent variables in this experiment?

  The diagram shows the pathway that conver4 e 1e9+x+al hmfz+cxvts 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 activk+mpb .jf75c aluxldc+om x( 9mh(n:6ity was compared with that of a free enzyme in solution. The graph shows the relative enzymep7ax .h5mmm+o6+lcjl k x(:fd9nu(bc 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. Which of thkex4 k5i1b9 jr2tn5miz a6t3b e following is the best way to keep enzykbe5i9bz1 mjai rk6txt2 n534mes active for a longer period of time?

  Which of the following describes some types7j-k pt.su 4yj of extracellular enzymes?

  The enzyme pepsin hydrolyses pro 6w(zt,s1vul nteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity anl1vt u, (z6swt 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 re(msagi vv(.p +glx4x *action of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C aaivl x( s*pvgg+4m. (xnd D were added independently to 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 actkmqnq +; v)zq3* f+ewjivity, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing w nf+zqjqkqm 3e+v;*)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 s mk r29jwnb7:jhown below. Inhibitors to the enzyme HMG- CoA reductas27: r9jnmbwjk e can 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 denaturat dk)q;fndwjx8 ,s d fh)76jtq:ion?
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 regro:mu2;ji 0:whtica cgsf 8uu *0p4.actions in the classroom and were given an experiment which demonstrated the effect of temperature onch0:f g*u .g sta:iucupwjm;0i8 o42r 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 increasr o/qx ;r qgr06qc-ro2fj94l wing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variab/6rr0qgfwrx oqqo; 4 -cj 29lrle for this experiment?

  A study has been conducted)rtj 2kuv hz)5b yr71j on the activity of a specific lactase (Bg10), analysing the effect of7th rjr2y5z j1kb)v u) pH, temperature and glucose concentration, 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 treating patients with m3h/x v./tobbuwl1b8 malaria. o /m18w /3tvbbx.hbluDescribe how anti-malarial 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 an enzymog2gp nn 0l-*uu1u5ij/5, qqzh bxqi;e affects the rate of reactionh;q-l q qgzouj,* 0i p5 /5nn1xiub2gu.
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 rfgk*cqv, pj r8hhr xh8tp6( )*eactions. Which type(s) of metabolic reactions are(hpc* jgqx8)fh *pvrh6 tr8,k condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways thea(6; fc8nmi-v2vtdlvi apc -4bx .d/f rate of enzyme catalyzed reactions can be measuredfa 6c2 bi4dv.m;vn-vf-(t8cxaip/l d .
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 contraoopnks;24d83w s o1iqr rrh,+ st intracellular and extracellular chemical reactions, given one example of each type wdro+8p2s ;io3s 4koqh 1r n,rof 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.