Which of the following macromo(+s(wntz ,chirk /ft6lecules describe a typical enzyme?

  What type of reaction is photosyntpn c0: rzfb,+yhesis?

  What is the substrate for the enzyme lactase s(wr5(o;h*ukcjz4g csi :2nook 6c k5?

  Which of the following stages of cellular respiration vk0xk8xb m94zv +yz d( 9sqixyw6 t0x01lr f+atakes place in the cytoplasyrsz+xfm0lxqvwv x8 y19(a9+d6t 0bx40ik k zm?

  Which of the following would not be useful in deteqi4 em3si)-0238z r wxhsf owormining the rate of an enzyme-catalyzed r-)34iw3qrexzms h o0o28wfsieaction?

  Which of the following processes mxus2;hh 8l(f2 2ql :nvz,wob lay be described as catabolism?

  Which of the following statements is best depiuo1 w/i3x o6dhcted by the figure below?

  Which statement about enzymes is np dtd zqb5 kg )p+uqze h22f967c/xv.uot true?

  Which of the following graphs best illustr z-is0.1uos5 ; )l ,ip k+lisqkkmwi0nates the relationship between temperature and the activityp 0l.-s qiks0k;1 okusiiw+izln) 5,m of enzymes such as lipase?

1.Sketch a graph to show how oh cu,cbd08.4: iqaisincreasing concentrations of substrate affect enzyme ac,a8h ic4s:ioq .cb0 udtivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catamr d36ty 7:f7pim8lgwv(7n c zq;j3ur lysed reactions. A diagram outlining the Calvin cycle is shown br7;tmd: lny6pjgf r 3c37v7 mqz8uiw(elow.

The image below shows the catalytic site of an enzyme. The sub.9h q *8gcw3nl+vt ms.qifx.rstrate is shown in black and i9 fr.wt.+c8slnimq*xh 3g.v q s 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 owy + iildz-q6rj0+s5d 4 m-zutf the enzyme catalysed metabolic pathways shown below? Letters rs 6ii--ddmq4lt +z5jy+zr uw0epresent various products of individual reactions.

  Which of the following descryfy( li 1)m jh07 zq9cnsp+5klibes the role of inhibitors in enzyme-catalysed react5y zn1+k7 mhcsyi09l)fl(qpj ions?

  Which of the following correctly descri:*y vl5rft om.bes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and mo cqng r/s 4kc-c-mu93ultiple engsq- nk/9c4cc-mor3u zymes.

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

  Which of the following best describes the inhibitor in thm0 ez7ux 2k2prmvruilidh- -5v* 4e)u/t ps+ qe image below?

  Which of the following statements are tr53 6 bwijgqg jm ;ywwz6b(01llue regarding regulation by end-product inhibitiobw 6 wlj56bigmqwl;j3z(g 01y n?
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 darken; n-l jy,idv5 yy+h8xbed structure in black is the substrate and is bound8jvi xyhy+ ybld;,-5n at the active site.

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

The equipment below can be use3y2v.s4l fa*s3+)q ecancux kd to study the effect of temperature on the activity of tx) alc3 se*cuyfk+a3 n.24vqs he 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 enzby jvu pxe:as5eu33p ++dvrbh ; 0c4m.ymes interact with substrates to c bj hb+sp:vcdexp3 04uya5.+;3 ume vratalyze 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 md*qx(juiia1 e/i4q f3easured.

  How does denaturation change the properties b s* z3xyn4pk3glm .p(of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the followinn::94bgemmt zg statements are trg n :9tzme4b:mue?
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 mammwxa6e5;, l mchp;gd*kals or endotherms from ectotherms that have fluctuating body temperature, dpxek w6hm;5 *;lagcs?

  A metabolic pathway that converts threonine to the end-produ r-km3- f2tc7-eu iflcct isoleucine consists of five reactions. Thrf e-mc2k-7ulfi3tr- ceonine is converted to various intermediate products 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 on the rate of an enzymatic f+rnj5w2x 0zsj2v )yoreaction)fr0jvsyz+ 2n2 j x5ow. What is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changin+5tlb53 opv uy nmxr1yozr++3g substrate concentration on an enzymatic reaction. What could be the independent and dependento5p3 oly yb xur1+z +3+5nvtrm variables in this experiment?

  The diagram shows the pathway that converts threonine to isolee- zvt1go .sb hio;0p-xy*szh9w o2) fucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobjjgbf+m7 , gj6ilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varyij gj m7fj6g,b+ng 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 denatu fn5v j6bl.-xre 14bsgred. Which of the following is the best way to keep enzymes activeg. vfn6brl1jb4 -xes5 for a longer period of time?

  Which of the following describes some types of extracellular eng1ft(//cwqa de1 d/duzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in tl b ap+vk5x*r(e6j9qihe stomach. A study was carried out to determ 5jl(i*k 6e+ 9baqxprvine 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 a d:3wg jalx+o )kf3r+en enzyme with increasing substrate concentrat3j3k +rfx ad+w)ge:loion. 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 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 xs3eh-czx 0fol0n v/2root into small cubes. They measured appr-c00sv ezlh2oxxf3 n/oximately 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. Iykr( -0q8nwh*(jh d+bq fd.h6)n cm yynhibitors to the enzyme HMG- CoA reductase can lower twy8 y*jfq-kc( nn+ 0)hhhdymq(d6r b.he 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 denat/ a)ynstgiemt.v 9(: vuration?
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 classrs )qczco v53o)oom and were given an experiment which demonstrated the effect of temos z3)cqv5 o)cperature 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 temperature on the efficie (hsw smme 4l*0 ,byals c2)rs7v(ob,bncy of lactase activity is tested. Which is an appropriate dependent var c*e,,bss(mom72 4 )l(savrbws ybh0l iable for this experiment?

  A study has been conducted on the activity of a specific lactasyo 0oy6og k(j1e (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commerckoyy 1oj o0(g6ial 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 ;ow xc 6mmjpjs3*,)y vfind new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered witsj),wxm3p*c ;vy6m joh 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 rate of reac:i zp32wj +qyrt3rwpz :yi+qj2ion.
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 synthesdwum2f; fqzxg:r8(w jj,bvv)ju4( )gized through metabolic reactions. Which type(s) of metabolic reacmfw2 z: ju,gfqb )v vr(ju8d) jwx;g4(tions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzeyu.v* .n/kq.wn3 l jzsxn94ifd reactions can be measureiz w/*k .3fn4q 9s.xvnn ljyu.d.
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 intracelejde90*; (n x 9rmmnuk64cgqd lular and extracellular chemical reactions, given one example of each type of reaccjn9(6dr4m uq90 neg;e*dmkxtion.
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.