Which of the following macromolecules de ; o6mdv0.me:clgyck o5v1 xc2scribe a typical enzyme?

  What type of reaction is photos x5ge)us3kkp xn69l6dj(xh 1f ynthesis?

  What is the substrate for the rz j/ ffk/n zt+d8u3x,enzyme lactase?

  Which of the following stages of cellular respiratiodb j h:/ 0hzajg08lhh5n takes place in the cytoplasm? /hh: gd5j jlbaz h0h80

  Which of the following would not be useful in determining the ratpijtzp p2z gwjg;kl9 )1l6i:8e of an enzyme-z 28kpl 9p;il6:tzjg1jp g)i wcatalyzed reaction?

  Which of the following processes may be described as calwg t q4c0lqnwre3w +;z(lh*,o+m 5ektabolism?

  Which of the following st ;kwu9cjlt,i ;atements is best depicted by the figure below?

  Which statement about enzymes is no5np q+ ov+tdj7vsg 41gt true?

  Which of the following graphs best illustrates the relationsen6 n.m9ih o:fhip between temperature and the ofh 6in:m .e9nactivity of enzymes such as lipase?

1.Sketch a graph to show hqvm82.gcpd8uw+k +c g d22g zwl8m-tsow increasing concentrations of substrate affect enzymtv wl82dus+2c.-8kg cdg 28 m+pw qmzge 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 diagra))t4ftzon4qfilf0 t8o7 9wkwvh0+vs m outlining the Calvin cycle owfh74siv n8f ttt))9zl4f+ovkq 00wis shown below.

The image below shows :j)arkoq ; bt(7 d4xc.ad wut5 zv2m)cthe catalytic site of an enzyme. The substrate is shown in black and is bound to thoa(rczkt).d4jb:wdcx;u7 5 2t ma)vq e 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 pathwkan2r na: ::ttays shown below? Lenkaa: 2 :nrt:ttters represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalyse vqgdx)xb+o:s1;9r t id reactiongqrb:idt s9;+ 1vxx)os?

  Which of the following correctly describes ph2wrqpa swt 9p h0++6smotosynthesis or respiration?

Many enzymatic reactions happen as pathways invb/nldaju1wi; 81sv)lolving multiple steps and multiple enuw1a) sljlbiv 8n ;d/1zymes.

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

  Which of the followinfa) z/z7yog:ng best describes the inhibitor in the image below?

  Which of the following statements are true regarding regulationm1vk y1:y dz*q by end-product i1y :ymv d*1kqznhibition?
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 enzyme. The darken8e whtyku1 k/3g7 h7uned structure in blk3 t7/w1g7ky8u nhuhe ack 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 us; jb4ah:owei;8 bw5 axed to study the effect of temperature on the activity of the enh5 ;b 48;aij:owbxaw ezyme 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 enzymewbt b* ;qr::qas interact with substrates to catwr;b:*q q:bt aalyze 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 enzya-mwr .c0*fq zme catalysed reactions can be measured.

  How does denaturation change the properties of an enzyme?2fuu7wf 3bsla7 yrpci2-y- 1v

  Enzymes play a role in catalysing reaction w6cz46q s5q;kjvi49nd e;ij.k.uao p s. Which of the following statements are e6 p;6a q4nuk5 .ovqjwciz4 sjkd.9;itrue?
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 ecto( f( zzrko3 gn)xvri19therms thv)rx9fg(r z(31oiz k nat have fluctuating body temperatures?

  A metabolic pathway that 3;si pt5h8jk mconverts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by differeskt3j5m h8p i;nt 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 ax stiyy7,sq g/ky )0yuaok*5:n enzymatic reaction. Whqs5i: yky,a)y7/s tu 0go*yxkat is occurring during the phase labelled section X in the graph?

  An experiment tests ma1v/ f(vgd m9*0scpjthe effect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables ind*vavp0mj1 /gsc9fm( this experiment?

  The diagram shows the pathway that converts threo* mx y41;4lher gr1 cj6bqt5jsnine 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 matrq/2qle*i8; o1a+w wp dvw1ca-af b6ky ix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzymefaay; p1*kbqa-vdlo2/16 e iq w+c8 ww 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 isg3jb pn9bb s8px 3z/mxr8 :m0p the best way to keep enzymes ax0m xn 398gbsm z/p3b8bprjp:ctive for a longer period of time?

  Which of the following describes some types of extrw)gl7a.jc 6buk6 m al:acellular enzymes?

  The enzyme pepsin hydrolyses proteins to :( mghjc f:ls1qh,)m mc;ae99kjf4mx release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activitygcf9 9)4xsqej(1 ch ;k,mahmm:lm:jf 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 sua cx.lz7mf(n)0) a wcp cl4/eybstrate 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 rea0xma)afe(/4cl7 c) ln y pwzc.ctions. 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 cut a turua 9dd.4h:vey i 67rmrnip 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 :m aru7ivhye.69d4rd 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. ;1,sdmrw 5kq+wb/sxwInhibitors to the enzyme HMG- CoA reductase can lower the production ;+1 w,rsw5 sw/mxdbkq 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 1vn 3gz:bzu) ,u-v f4ntros4dinvolved 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 reactions in the classroom and were givenwvuz fbs7o/ y6wb20 z4yh90py an experiment which demonstrated the effect of tem wo/0fh wvb74szy069y2u bypzperature 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 temp xewlgsr)u+8g *wo ,u4erature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for g4),+ gs xwlu u*eo8rwthis experiment?

  A study has been conducted on the activity o 6xg z9- 7trfmb1:d,ud9;wav2pux noof a specific lactase (Bg10), analysing the erx m-2za6pt:d9d b go wfu,9vnuo7 ;1xffect 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 find new drugs for treatingq k)aod 9ma3j--/ ixrb;3 nya 16geivh patients with malaria. Describe how anti-malarialh1nij i );6gad -3 3k-qyamrabv/ox9e 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 the rk;xa/b4 mkn*q1c9tkur sqw:+ate of reactia tq; 1q:crx+49mku*w/ kk snbon.
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 throu 1/zw6 7rinjo.+fz,7eci u/ oltzow.ugh metabolic reactions. Which type(s 1.uozl n+76ww.rfo/o/c7jz i,i utze) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be meqya0e:;/+bnms,kbq c tyc pk: lg (o74asured,7+ye0 q/n py4lqckbk:: gso ;tab(cm.
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 extracellular chemical reactions, w7;p m an+c.qvgiven one example of each t;n. qw+cmp va7ype 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.