Which of the following macromolecules desx iy+pf57,uas cribe a typical enzyme?

  What type of reaction is photosynthewsnb,n-brpwf .m z(4: sis?

  What is the substrate for u 0c; t:z*rmnwzzy-:ug(5susthe enzyme lactase?

  Which of the following stages of celluq pbk -h *p-hr92 o(wjpin79bdlar respiration takes place in the cytoplasm? n*i2wkr9j97h-( hp-do pp qbb

  Which of the following would not be useful in determining the rate of an enzym,asaq6/bh;ef2;m+mm)u46y j nhoghg e-catalymaah/h+s;u,gqmfh46e 6gon);yb 2 mjzed reaction?

  Which of the following processes/)*fag,.sfc7v 5xtgekl u yx1 may be described as catabolism?

  Which of the following statements i,4bfb5lj ( eans best depicted by the figure below?

  Which statement about enzymed3 cuzvnb8kl5*5m1xys is not true?

  Which of the following graphs best illustrates the relationship between tw lse: au5b3epx/c4h ,emperature and the activity of enzymes such as lipasep4aew5:x /l s,uche b3?

1.Sketch a graph to show how intt,n tp -zt9m4creasing concentrations of substrate affect enzyme activity,z4-mp n 9tttt.
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 .gqer-tnig5 4 diagram outlining the Calvin cycle is shown beloe -r t.gg5iqn4w.

The image below shows the 9 cp) :xbibj4xcatalytic site of an enzyme. The substrate is shown in black)i49b:jx bxpc and is 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 descriptions of the enzyme catalys /cmor5r0e2ke )pjj 03 utu *lg(/hszk;hves3ed metabolic pathways shown below? Letters represent various products of individual re0 r 3 k ;vouzut/30sh *hermgepl(/j5js)ce k2actions.

  Which of the following describes tjm yvq:k p9hru22 di8.he role of inhibitors in enzyme-catalysed reactioq:pkvi yj9dru28 .2mhns?

  Which of the following correctl,e v6 p- bswg;2r 6ansp5oq pa65zn0moy describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways i-alku81c mode:r+p *h nvolving multiple steps and multiple enzymecum ko+:8- he 1dl*rpas.

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

  Which of the following best describes the inhibitor in the image belo8 9 mh6 eoof yu(,rolf-c6uvnlsd(l-/ w?

  Which of the following statements are true regarding regulation by end-producpa pjk:8+ hpa;voe+v6t inhibi;kapahp+p8+ 6vjve o:tion?
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 shows47o8w ka nl*rkgco m4r,82ep x the structure of the lysozyme enzyme. The darkened structure in black is tgc8xe 4kn2k4w* ,r am7proo 8lhe 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 7 nua-(7wb//qa kluywto study the effect of temperature on the activity owq/ ( 7uwk-yan ubal7/f the 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 statemen4w.j h 3qukrr4ts describes how enzymes interact with substrates to catalh.qkjr43 u r4wyze 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 cata,9ht ilb, uvz b3r6yc+kq:lvd)/z r+rlysed reactions can be measured.

  How does denaturation changekyj 4e,g4d7 4fb lvbb- the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stgh le.3y-wedh) w5 of2atements are o35hd whl.fe 2wyge-)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 e17w8kh/i(ja f*c cn t k(h-ybmndotherms from ectotherms that hw h tk/*- (yinjab8cchk71fm(ave fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product mev w s89ecets9p+b wiye-,*8isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially ps eyb eswe-m 8 9ev,wi+ct9*8by 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 incre jnmnt+meoq27r 8x1p wmyy .10asing pH on the rate of an enzymatic reaction. What is occurring during the phase label.1tmjw8+nmxpq07 2ry n1 myoeled section X in the graph?

  An experiment tests the effect of changing substrate concentration on aloy7uky;d9upct e6. zxr-v1*n enzymatic reaction. What could b zu vyyd6rxe p*7-ltu c9k;1.oe the independent and dependent variables in this experiment?

  The diagram shows the pathwxp o5 ibn;9us3ay 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 activ y,iswgdhvk2 . ged*+:ity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) w e.yivgkh +2gdw,:*sd ith 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 bestqr5 f-c w;uhc,w.v5 2oqkfouu4 w/8be way to keep enzymes active for a longer pe5cqoohruk2vf uqf /wu.e-,w w b5c 84;riod of time?

  Which of the following describes some types of extradvi6 ,sr0/-sc,d e yd 8ynohz,cellular enzymes?

  The enzyme pepsin hydrolyses protevovi )-c u1cda r7z0t9ins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme 1dzcv90ao7 -ticr )vu 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 wio-8 wd9t xdug(th 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. Thed-tw gx 9o8u(d 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 turnip root into small cubes. pm njop8u:w1.0f qr,k They measuredw mf0 .p:ojnqukrp,8 1 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 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- Co3p7 ur2c)frjoa yd(y j,qh aab2c8u7+ A reductase can lower thaarc2o)32yy b+ufj7j hacu(pdr 8q7,e 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 /g)7ln ilky k4g9q u5f 3tnp2 rcvv(,zare 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 reactions in the classroom and were gi k xbdt1qm 7wkz3*h09xven an experiment which demonstrated the effect of temperature on a catabolic reactionq 7xb *0kzk1x39dmwth .
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 efficiency of l5d 4j 5k4ggofpactase activity is tested. Whicpgdk4 gf4oj5 5h is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analys,3tt(fl,sxvg+n3 7wlckcci* 6 gl6a ping the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactf7p(l *,lc ,w6 ttan+sc 36vgc gxkli3ose-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 druqep i(:kdnir0h ,(bl,gs for treating patients with malaria. Describe how anti-malarialh (ne(krdlq,b :,0i ip 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 +yxax 8fi7y5 rconcentration of an enzyme affects the rate of react frxa587y+ iyxion.
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 reactions. Wnaz8xzo(a.ibe, h7 w. hich type(s) of met baoz.ziw 7a,(h.xen8 abolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reac.8recl;je yvq 7v8g-ctions can be measureyeq ;gvc-8c8r. lve7 jd.
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 intracazrh: +azmwxs8 j6 nsgy40,dcu5 p b23ellular and extracellular chemical reactions, given one example of each typemuw2pjhgy s85 n, :4rcaxdbsz0a +63z 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.