Which of the following macromolecules describe a typical enzymc2 vrs7t5t w3ce?

  What type of reaction is photosynthe:+ u:p awyea8qsis?

  What is the substrate for the enzym+om0nvg+0cr h,t8gt h4 q/ r,fwoqo.ee lactase?

  Which of the following stuydyqpgk f+n+4-1 3lv ages of cellular respiration takes place in the cytoplasmv +d-pyl n 1u4+3kfgyq?

  Which of the following would not be useful + oeoio v/.va+i(v8qy in determining the rate of an enzyme-catalyzed reactioov e /io+vy+i8q a(ov.n?

  Which of the following y(k ef:n5k,dqprocesses may be described as catabolism?

  Which of the following statements is best depict7hnyc fm/9 dc*ed by the figure below?

  Which statement about.o- ua ,-0.7wi w8 kldyd8si tfkiy21ej/udt e enzymes is not true?

  Which of the following graphs best illustrates the r+(ojaetcv. v *elationship between temperature and the acta*jovtc .(v+e ivity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrat3r 2qr-rcnp lig,:f)1 imhk:re affect enzyme activity.rfnkcr :3),p2:im1ri- r hgq l
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 diagr4k-abbk4scn00nqt3 i .w9n-e; t eglpam outlining the Calvin cycle is sholt3n p;4t4ebw9e-b.gnk-sk i aq0nc0wn below.

The image below shows the catalytic site o*0t+ zl7gbq 3thr7yyof an enzyme. The substrate is shown in black and is bouhl0oy7yt r g*+tbzq 37nd 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 des* 99slr gwk,0 dfgofte8; mqp3criptions of the enzyme catalysed metabolic pathways shown below? Letters represent various 8 0*kol9rgefgq9sdftm, 3wp; products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed reavbawedm6h .:7 os(k)sct h os :wv6md7(eba.k)sions?

  Which of the following correctly describes photosynd;p/pt(ldrf/eq n 349o9 zsuwthesis or respiration?

Many enzymatic reactions happen as pathways involving multip;qx1.u71 (xryu g ekohle steps and multiple ekue1.h(7oqg1 y xru;xnzymes.

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

  Which of the following best describes the inhibitor in the imagewlvc 76 29tofh below?

  Which of the following statements are true j:3znfd yi;8zz7x*myregarding regulation by end-product inhibizy z7:ijf*nx8 3dzmy;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 shows the structure of the lysozyme enzyme. The v9hgtyn,yd;+ezv4f+ darkened structure in black is the substrate and is bound at the afv ;9n+ez4dy+h,tvy gctive site.

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

The equipment below can be 4)o,dwt- txxn used to study the effect of temperature on the activity of the ex,ttxond) -4 wnzyme 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 de33 ir-x.gusy xps6io1 ,+snjfscribes how enzymes interact with substrates syx3 if-s16puinx 3sogj,r+. 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 xk7zob ak2dn1* ,-qmq catalysed reactions can be measured.

  How does denaturation change th5q su82k/ba (rg w1 xxhkkp5v7e properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the fo,y :0wswk4r) use; gopllowing statements areo 0 krw:syuw)e4 pgs;, 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 by rssn*3je.l*xv ,a0endotherms from ectotherms that have fluctuating body temyjln,0*xar . se*bvs3peratures?

  A metabolic pathway t t,lnkm,3 da(rhat converts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzydaltm (,nr 3,kme 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*+lj e:b ivql ft6*ie6pm;/xgifw15s the rate of an enzymatic reaction. What is occurring during the phasw+eff q e*l*lbmis 6:5gj 6xp/i;ivt1e labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzymac):eyxggf(th73uay 7 tic reaction. What could be the independen x3(gfg) :yut7 hay7cet and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucinwbj)i1k e8ab-e.



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 1vi0e)0v4d o; jio bxciw6*nuwas compared with that of a free enzyme in solution. The graph shows the relative enzyme ace)i bv0;xo n4 ovi1c0udi 6*jwtivity (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 w3(cvgwbij j,o;h ;sl9 2t u)iway to keep enzymes acil9wwhgcs)2 ob,j vui; 3(jt ;tive for a longer period of time?

  Which of the following describes some types of extrace1 us6b+,pdpw pis- ji43syw ;ellular enzymes?

  The enzyme pepsin hydrol,i s72lrsy o*wyses proteins to release peptides in the stomach. A study was carried out to determine the effect ofo2slwi y ,*sr7 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 increas) . /g) s6me5tmjegyahing 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 coinc e)s/ .jat )eggym65mhides 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 turnigp +lof9g067hysy0v va 6i9b kp 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 filte0+ ok9v fb0 y769i6lhyva gspgred 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 enq38liqa4p(p4j be 5 j) yc iu8u(ug.ebzyme HMG- CoA reductaqjbjie5ug. (a qi)cup8(be4 yp8 34luse 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 invd;jak8gz)bg6k,kxq f:i b .+/tsc y:rolved 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 t065t p:apc(pxaf 6a u hy1ojz/he classroom and were given an experiment which demonstrated the effect of temperature on a catabolic react (cpf j1a6taz o/u6y5phax 0:pion.
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 84*pytpo e iefj18rewkjr6am*n5o4l6 3wc b 8of lactase activity is tested. Which is an appropriat8e36b 4wmwf 6j ty8ija4oce5l* nkpo8 rpre 1*e dependent variable for this experiment?

  A study has been conducted on the ac-8ioz ggs(, xptivity 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-frei ,s (zgx-8pgoe 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 duwlx47cz6s.mg dc6ke +a y79drugs for treating patients with malaria. Describe how anti-malarial drugs are bein wlyk.e+adx9dz sccu64m76g7g 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 eqwrx1ppe)9u 8nzyme affects the rate of reaction u8ewr)1x9q pp.
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 r 8 hsrgswz3:eli9r*jitr04p) vjy*4 k eactions. Which type(s) of metabolic rel9*sr8 t*4j v)i4 p :erkgwi 0yjrsh3zactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzymez/qm xe m+5 2cb4sm ;zeyzy32w catalyzed reactions can be measureyz wqmee/zc4;2sxz 2y+3m bm5d.
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 extracext7 :hok8) ahuxr. loj6i j6hp i8,b*bllular chemical reactions, given one example of oiijjth,o7h6r8)x a. *xpkhublb86: each 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.