Which of the following macromolecuc(:oo , nv6lc)-, b.xiswf laqles describe a typical enzyme?

  What type of reaction is phowpri;3o2b* t6hrb)3 fgeao7n; t ffr 1tosynthesis?

  What is the substrate for the enzymeezk j1 rp*r2w7m)sz)o2mp +hts: wlk2 lactase?

  Which of the following stages of cellular rputuf+)d37* pgch mu- espiration takes place in the cytoplastgu pch u-+pmdu)*3f7m?

  Which of the following would not be useful in determining ie6 l) d:7iejsra*rd-)q ;ven the rate of an enzyme-cata):sdr q )7n;6-ard eel*i vejilyzed reaction?

  Which of the following processes may c -8jak8oqkh1 be described as catabolism?

  Which of the following statements is best depicted by the figure belo9(f*(m )u rfjp+ vghv/5v +gho vgn6gvw?

  Which statement about eap tczisv8r9f )3 86/dsh7olinzymes is not true?

  Which of the following graphs best illustrates the relationship bp;t/ *gb;wqx xetween temperature and the activity t*pb/x;;gxq wof enzymes such as lipase?

1.Sketch a graph to show h:c oihulp;5t 5ow increasing concentrations of substrate affect enzymi optch5;5:u le activity.
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 o+(c. ct7n-v h.serr5pg (mnou utlining the Calvin cycle ir5 msvc+ u(g.etnnrhc 7 op(.-s shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown in z)cnq;1af iwez.-u/b black and is bouz-euz 1)/ cfai; .wbnqnd 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 pa5p pct6ny- *lcthways shown below? Letters represent various p-6 ycn 5*plctproducts of individual reactions.

  Which of the following describesfy 4 q:1ouzhvu;34ctz the role of inhibitors in enzyme-catalysed reactv4zyhc4ou3 1t :q;u zfions?

  Which of the following correctly describes photosynthesis or respiratio7g-3d e tkjelqte,vc:ec .4(un?

Many enzymatic reactions hylks:-yy / 0.r/y+9t6u djl,lazvmt fappen as pathways involving multiple steps and multiple enzlt6a l:fu y t.d-m+0y v/jsy/kl y9,rzymes.

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

  Which of the following best describes the inhibitor in the img.ir,ba x( fy)age below?

  Which of the following statements are true n+iryijb5s+die +(y6regarding regulation by end-product inhibin e(b isdy6i5+yi++rjtion?
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 struk7dxd; v.nucpt)2xx/cture of the lysozyme enzyme. The darkened structure in black7ucxp / 2.xnt;dkd)vx is the substrate 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 k 7p o+/v(d06hou)5o wtcacfistudy the effect of temperature on the activity of the enzyme 6v7h +ckao (5/0p )wditfoco uamylase.



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 e/;j30pdb0ve a6 oxut interact with substrates to catalt6x/d o p30 ejv0;euabyze 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 m-l)b m imw 9ur,j/ ua/+2fifdqeasured.

  How does denaturation change the properties o sxzawb07zz,wg61:8w *kkhn;smx5 a gf an enzyme?

  Enzymes play a role in catalysing reactionsrnhe4r -)ve14 thpyij83nd n7. Which of the following statements are truntd i174)3vrne hr-eh4pnjy 8e?
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 ectotherms7oy j *z4mb-y*a0ir8j kdca9xrey5 u3 that have 3xymy9*oje ray87*0ib5 zujrk4- adc fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleuc c5jf fvmj i1;cqs77t-ine consists of five reactions. Threonine is converted to various intermediate pr7vs;ti1fj c 5q mcf7j-oducts 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 o19oge*xdtc *6,khzdhgs10g b-gl zm/o3z7h pn the rate of an enzymatic reaction. What is occurring during thek x0hd9h e 1b gos/g z*m p*7dh-3z1ggo6t,zlc phase labelled section X in the graph?

  An experiment tests the effect of chamx tce/8pw- kdrqja 6)w-a 31yto, ,snnging substrate concentration on an enzymatic reaction. What could be the independent and toej -3d/ q 6w8nct a1x),ka-yprs ,mwdependent variables in this experiment?

  The diagram shows the pathway that converts tnii6vzx(g*+j 5:a tujzr;*aju*w(e ei q vf*9hreonine 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 w01;xb (p fi4fe (tvumbas compared with that of a free enzyme in svbpufi0((b e14mt x; folution. 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 easily denatured. Which of the following is the best way to s-.:*x)17ja do6oxrbq xxoq s keep enzymes active for a longer period of x1 s ooodsx7.6 *qxa -j:xbr)qtime?

  Which of the following describes some types of extrae( ;un leo(nfn2 p)2 0cxi1fidcellular enzymes?

  The enzyme pepsin hydrolyses proteins to re6p9nee lr d,g;(-zzby lease peptides in the stomach. A studpgzeyzl,;ebn6r -d (9y was carried out to determine the effect 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 increasing subsiao(ci41l . ghtrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monitored f gi aihc1.l(o4or 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 activity, a student cutfn.b sb+0xumu-2f8wz 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 test tube at roof b8n2w0fsb. uu-zxm +m 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- CoA reductx mu ol i526s1j(gcel(asil(j glc(5s um26o1xe 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 a dngd9uoi,6 qu)e v+y .xb4dej10mhk9 re 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 metabolic reac(o y,5w nzt+ ktc4k,vltions in the classroom and were given an experiment which demonstrated the effect of temperature on a cz4+ y,o,vknt5 tl wkc(atabolic 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 efficienjynop i2/; t- cc2*phycy of lactase activity is tested. W2n2yh /;cicpo*-j yt phich is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of nn;bjb iic96t/nl e rdl*/4 eor78g.za specific lactase (Bg10), analysingr.nel6 ie *c/ z;4jb 7li b9gntond/r8 the effect of 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 f6j,ftqa qv1+ iind new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with n+ijtv q a6f,1qew 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 ofu+rc04y;u4tvqkwkw) yli2h / reactioc;i4y uq ur2h)wk+t04/ywk vl n.
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 synthesizlwg9mt-muy+n3h1l . *zxs8t ced through metabolic reactions. Which type(s) of metabolic reactions are cn8z-tmthy9l1g s wclm*3 +u.x ondensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ( 3g3bvht4uum3n 1vgl ways the rate of enzyme catalyzed reactions can be measuredvggm33 1vu3thb(n 4ul.
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 intracellularxcnyv /n3l(m8 and extracellular chemical reactions, given one example of eachn 8( ly/xvc3mn 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.