Which of the followigar7augthj,0*e,uv 4d2 lo5 bng macromolecules describe a typical enzyme?

  What type of reaction is photosynth:u gbzxn(k9;z -of*dtesis?

  What is the substrat gi772birvsx9 ahh/3 ;g6u rpue for the enzyme lactase?

  Which of the following stages of cellular respiration takes place in the cyta)ijncl 6wi lmw9 201sopla)9icas2l06ljm w ni w1sm?

  Which of the following would not be useful in determining the rate of an x910 e pnupungl5qyf rcg*7 .2enzyme-catalyzed rer xungn g21cl5p 7 yuq0ep.9f*action?

  Which of the following processes may be describdp1dfl+( k)wc9v,u a ted as catabolism?

  Which of the following statements is best depi.;6f(m wf7 lqq2kzq oxcted by the figure below?

  Which statement about enzymes is not t7, je,q cr iurbnsk++5nbme3 2rue?

  Which of the followik q,jqg9g xt1+wwlr,2ng graphs best illustrates the relationship between temperature and the activity of enzymes such as9 x12gg+qj qrwt,l,kw lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect ev b .i2cgwfzc l,m;-bjla4j.9:l m*itnzyme actilv-.l;ij,jmm i fb.wzlg2b*:a c9c4tvity.
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 diagram outpdz6w,thbn7qd t 8 8pq2bp)k *lining the Calvin cycle 2qb 8z*wp8 k dd),t tn6bqp7hpis shown below.

The image below shows the catalytic site ofya4vchdy7ivn5u:8 *p an enzyme. The substrate is shown in black and is bound to the active s*:8y5nypdh7avci 4v uite.





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 pka;v 4x*esui a(bfufr 56(i p*athways shown below? Letters represent various products of individual reactior*a(b5fsu 6xp (v 4 ;kfi*aieuns.

  Which of the following describes the rolb ,- gjhedjd,armf 79(e of inhibitors in enzyme-catalysed reactio(ar,jgmd d,9 bejh7f-ns?

  Which of the following correctly describes photosynthesis or 7 s.fi1pqg,) psu(d8aw rfmx +respiration?

Many enzymatic reactions happen as pathways involving multipl3 0cpt,a1;oqe qscj.fc y,xm ,e steps and multiple e.pse f;oc1xjq,m,tq0 y c3,ac nzymes.

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

  Which of the following best describes the inhibitor in -g8 oeltnh-8 gthe image below?

  Which of the following statements are true regarding regulation byf1pb0)ba2 wy va*xfx- end-product inhibition?pxb2f 1y b*wav-f)ax0
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 lysm70(h rgn u* /k8:z;ewgsy.pm9fbeapozyme enzyme. The darkened structure in black is the substp/fak e0;rm(z u*98nsb 7wg. epgy:hmrate and is bound at the active site.

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

The equipment below can b0qoi)1. vto)h v tc;*w,wssibe used to study the effect of temperature on the activity of the enzyme amylase0hbvv s;i) tswwi 1.)cto*oq,.



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 interact wi7c x.i:e gy39shcjbl*th substrates c.cie:gx7jyb3sl h9* 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 reac 9*m,pja.a9 um*v ekx/zcwz 9ttions can be measured.

  How does denaturation change the properties of an en,qqzd2c1p zp-s vm8f) zyme?

  Enzymes play a role in catalysing reactions. Which of the following statementffb+6l3 c.nfks are 3b.cfkfn+6 lf 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 characteristih k6keqd/4;jl: p o6) jc7ky:cjyh9 uzc that separates mammals or endotherms from ectotherms that hd 6c)/:u jhk ep kjlh9yoz;6jy47kcq:ave fluctuating body temperatures?

  A metabolic pathway that converts threonine oe,e*sd 4f..4 kimmqc1uz r:qto the end-product isoleucine consists of five reactions. Threonine is co4 oq,fmru:cd.z.4 ems1qkei *nverted 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 ra38ksy 7wnhd1ste of an enzymatic reaction. What is occurring during1s3sy k7 nhw8d the phase labelled section X in the graph?

  An experiment tests the effect of cbb,qcxa96 / vv yub /gw9f,wz-/6/mfwp5posehanging substrate concentration on an enzymatic reaction. What could b6wf,/zc,y5 /uo/spbw wx96bfge 9 v-m ap/vqbe the independent and dependent variables in this experiment?

  The diagram shows the 45,xmoeqao9xo,h )tw k(l; sw5x,cbh pathway 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 matrixa7phq(fv z n 832k/qgh5i,ny o and its activity was compared with that of a free enzyme in solution. The graph,5n2a/zqy(7qv n8ki h f po3gh 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 easily denatured. Which of the f7/nb3ebe0qp q2l6 +scgyz(l2a8zx n l ollowing is the best way to keep enzymes active for a longer perisl 3q07b6( 2ngzyqp a2+8x/bee lnl zcod of time?

  Which of the following describes some types of ex9-a he2ekgh4devr- + ie.wsz8 tracellular enzymes?

  The enzyme pepsin hydrolyses proteins gglb(4hzzbj.crp:/hrc. 1 3q to release peptides in the stomach. A study was carried out to determine the effecqhgcb rb.1z(j.p4 /g3rz :hlct of increasing substrate 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 shows the rate of reaction of an enzyme with increasin+l+made dr. : l))fen:w0wyzfg 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 curve marked A clr+ml:a0+zee) df.f:d y w)nwoincides 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 activitaq,b a88zu 2dgy, 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 liquid extract was stored in a testbqu,z8a 2a8dg 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. Inhibitors to the enzyme HMG- Co4 b3m57i0rz7fohovu q.x9 cp7bz/x x rA reductase can lower the producth7iv.o4x 75ufoxz 7pmb0 q3cb/z 9r xrion 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 ae5y 7 l3ftfnw egy m8*i)t(8lmre 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.j (daz,)j9 zfrjhl2j metabolic reactions in the classroom and were given an experiment whichdj9z(j2 fj,r. )zljha 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 increaz w0y-f/ wdb/xnm-l,o sing temperature on the efficiency of lactase activity is tested.b, mwonf w/x -y/0zld- Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10 s3ur7i1 lrqy grh*)j6), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase torr hl61g 7ri s3)yj*uq 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 pati3w no qh4ibg )o0j)gm3y xsr/1 zr5x/i5f0fadents with malaria. Desc 5 /g ioofbg)3xfnwjsr3yar10q0ximzhd 5 )4/ ribe 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 enzyme affects t01a(wptts /w ehe rate of reaction/1t( swtw0epa .
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 metaboxg 0j 2cf 91i*ws+ocjzlic reactions. Which type(s) of me2jfcjx9z s01w +o* cigtabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of en4ph 3r ck ,)2iusmrl)p*)aq gw0pkr*szyme catalyzed reactions can be measursp*4 r)psmr02k 3gklqracu *)ph,i w)ed.
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 eo25jhduf +t +v4jmk1 bxtracellular chemical reactions, given one example of each type of rd jm t2ujv41+b fo+kh5eaction.
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.