Which of the following macromoletgw15ex 8 8--iqw) ef7j6 cx :gjutedgcules describe a typical enzyme?

  What type of reaction o o5g2y mp9s b2oi*rw+is photosynthesis?

  What is the substrate for the enzyme lactase?v7 tzbr ,wvrh*bvcy,x40wf dp19hb7 :

  Which of the following stages of 2;;iqnmf*q bww9t z7o;u bpp4cellular respiration takes place in the cytoplasmn ; o;b4wq97;mqwfb*t piuz2p?

  Which of the following would not be useful in determining the rate oyfaw v4o2qs/i8fz1+ t) q.tmff an enzyme-f )vwq/ .oy +q fi2st1za4mt8fcatalyzed reaction?

  Which of the following processes may be described as chzh0 :78i7-nkllzet2kp zsh 7atabolism?

  Which of the following statements is best depicted b:y*m ahy59iaw y the figure below?

  Which statement about enzymesk nhfptqse0- n*510pk63oexsgu,9ga is not true?

  Which of the following graphs best illustrartz -bpb( t*l.wtl7o7j)ez,u kk0qk5tes the relationship between temperature and the activity of enzymes such as ljtb-k ,(r.77k50zk*b pql lttuezo)wipase?

1.Sketch a graph to show how increasing concentrations of substrate af,hlzvfge.6 ue - ;zz,ffect enzyme activif,zv ;eeg.,fuzzh 6 l-ty.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of en izwfx4ddhp6e22; :qhzyme catalysed reactions. A diagram outlining the Calvin ihh fxedz6 22d:w 4p;qcycle is shown below.

The image below shows thec9vmp () 7tap 7j7w7h9n imiol catalytic site of an enzyme. The substrate is shown in black and is bound to the active sitel9mona vicw77p tm 977i()hpj .





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 pathnw e-ri;r0o7yways shown below? Letters represent various products of individualie;n0o ywr-r 7 reactions.

  Which of the following describes.tdk,sg wf37r the role of inhibitors in enzyme-catalysed reactiof 7skwtrd3 g.,ns?

  Which of the following correctly describes photosynz i;rc 2d)dde:thesis or respiration?

Many enzymatic reactions happen as pathways involving multi z/;m +ie-zoiople steps and multiple enzy;mo z-ii+ /eozmes.

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

  Which of the following best describes the .x90otx,l k1 hhorl;v inhibitor in the image below?

  Which of the following statements are true regarding regulation by end-prodhu. wc8yu3 t1fmay c78uct inhibitionhafyw3muc8t.u 1 8yc7?
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 kzimn1.q)e 5a shows the structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bound aa.mq ne5z )ki1t the active site.

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

The equipment below can be used to study the effect ofnp a*;oeh3/, mwjv0:1a tdirx temperature on the activity of themj3i *v : ,px0ante1;dor/hwa 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 interact with e,y uauxk):+isubstrates to cataly:u )u +aix,keyze 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 catalbqfllr0 tqga-fhy + m9,q,f5.ysed reactions can be measured.

  How does denaturation change the propercg8(2q sz/ fhvties of an enzyme?

  Enzymes play a role in catashqgy,b4 9rtho1z0 j j ,/2euulysing reactions. Which of the following statements are trh9s1t4g,hzb/e ujj2 ry,0o quue?
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 fron) c .uc jziq9gz 3ai81(b 33xgt(ekllm ectotherms that have9glja q3 (bzkuizg3 (l c.e3nx8c t)1i fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-proby/ rtm8 gfiu +;wn/z4duct isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes befo/nu z w4ti+b fmry/;8gre 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 increasinb0,a xvut.+vmoc ;my;g pH on the rate of an enzymatic reaction. What is occurrinmut+ba,om0.v;y v;cxg during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzymvd,*6p 0 g7bpfwxq-g uatic reaction. What could be thf x 7p06qg ,pbv-g*wdue independent and dependent variables in this experiment?

  The diagram shows the pvb x /l9lsk7zk kz65y-u46w ylathway 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 wasmu2fn 1samln,9kt b .81tth u: compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (t28h1am 1lbtusnmtf:n ,. 9ukx-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. Whiclx :amx+i 6jhjh/jg* 1h of the following is the best way to keep enzymes active for a longer period:+ix l jmjjh/1*xgha 6 of time?

  Which of the following describes some typeszou1ccd y5kk.- 91ibc of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the sq+uk1e+f y,c)hasw7h( hx qp 6tomach. A study was carried out to determine the effect of increasing substrate conupy hq sx6ha(c+f7 1+q)hwe,kcentration 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 v 7i h1 u.nu7ykmg:-hpreaction of an enzyme with increasing 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 coiui hky.uh-1m:7vp 7gn ncides 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 activf i7y+uk/ ;7+ktrgtwgity, 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 blendwfr+;igk /ky t7tu+7g er 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 shown below.,vgy b29f u9 52ydgokb Inhibitors to the enzyme HMG- CoA reductasebgubkf2 259 9dyoy,gv 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 dn z z(q4*lziu8i kikdj5cm6* +enaturation?
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 metabocakqacwa )- ty 7v(,*klic reactions in the classroom and were given a q ,k 7actv-ayck*aw)(n experiment 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 te (4a e:cj9dcjbmperature on the efficiency of lactase activity is tested. Which is an appeabjccj:( 49d ropriate dependent variable for this experiment?

  A study has been conducte8xk i xob7l7i5,vg)bh d 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 lactose-free m8h,7okg)l 75x bvbiix ilk.



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 wcb:a q9j:w:86oye yp/: vx0flm4ab tgith malaria. Describe how ant4yt :qc/ob6 :wlpmxabjfy: 0ga8:ev 9 i-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 affectsqvc6ygp: h eb3:qk8( f kw+g*o the rate of reactionocqf( :kv+*gwe 3g h kqb68y:p.
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 throurt2sd1hwop8nv :o7 .yn e3(kfgh metabolic reactions. Which type(sek1fhrnsd2n8 73t( .yowvo:p) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactionsi482pk.ot bq v can be measurboi 4vp k82.tqed.
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 i77zukexglyd 4*fe95 cntracellular and extracellular chemical reactions, given one example of each type of reacti*9kg7 u 45lefx 7zdecyon.
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.