Which of the following macromolecules describe a typical e8k,y1, jbjhp enzyme?

  What type of reaction is v narb6 )x07fvphotosynthesis?

  What is the substrate for the bce s1mmeke;ze;d;(0 enzyme lactase?

  Which of the following stages of cellular respiration t wdltcno, 84zshgo ,u+s t p*gwe-5s12akes place in the cytoplasm?gwoh 5,cz-ut +8des tossn2 p*wg4l1,

  Which of the following would not be useful in determining the rate8ns hqglaef;+ad ).w* of an enzyme-catalyzed.8wfl + qgan;sa dh)*e reaction?

  Which of the following processes may be described as catabolism,hgw)iunf g)utwzc53 9, 5yyh?

  Which of the following statements is best depicted by the figure below? sig5og, m. 9ew

  Which statement about enzymes is not tru.e6 s/b 7d -wcai1zchzsv,zb6e?

  Which of the following graphs bhj6 1c)tw;8i zhsfwezsi+5 k:est illustrates the relationship between temperature and the activity of enzymes s):1fti5zihh 8c z6wjkw+e ;ssuch as lipase?

1.Sketch a graph to show how increasing concentrations ofg0 (qjexoyb 6.thtz0: substrate affect enzyme activity. h(0bx : yg6tojz.et0q
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed re,2ri; cug6cm: yhc: aeactions. A diagram outlining the Calvin cycle is shown below. 6 icmr;c e: :hu,2ycga

The image below shows th2fi;wcc/m t8 he catalytic site of an enzyme. The substrate is shown in black and is bound to the act; cimcfw8 ht/2ive 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 descriptinf w/m8m m 5(+,l8owmhwc5v kbons of the enzyme catalysed metabolic pathways shown bel5( fm+mbk8 ,8o 5 vwnhlwmmc/wow? Letters represent various products of individual reactions.

  Which of the following de:9:zy+jadcu t y;o1sv scribes the role of inhibitors in enzyme-catalysed reactionsj;yc ous d:vty1+9 z:a?

  Which of the following correctly describes photosynthekl7,ym -t,bvn sis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps anlaz;wn2 dv :ue-x/ ;ysd multiple enzymes. syu ;l:/nzx2vd -;w ae

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

  Which of the following best describes the inhibitor in th2,j wx qh fa8ot+o5a4(kadz1ee image below?

  Which of the following statements are true regardi0e 1ivr0 50x:rl*wlf jkg*g4juub ah(ng regulation by end-product inhibi 01*i40khgwb jer(5flu*vj0gx a ru:ltion?
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 darkened ym j:vil;8) 9sf66av ww;mxuistructure in black is the substrate and is bound at the active site. m6; 89xlw:ai;v6yms wi fu jv)

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

The equipment below can be used to study the effect of temper*x(sljwtu h4: awzi ammh hl,nv2/s: ( s1e3r/ature on the activity of the enzyme amylase. zslu:(m/ ,vlh(3i xnja w:*4hw / ta2mhs1sre



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 yhvuzma ;,t+ .how enzymes interact with substrates to catalyze react ,zym +ut;hv.aions?
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 reactions9tij+fvw 8veu4ao k, 3 can be measured.

  How does denaturation change the proei j 7s97k26brdjy42i5z dvpoperties of an enzyme?

  Enzymes play a role in catalysing reactionxh;sr a;a68vt s. Which of the following statements are truasx;6vh; ar8 te?
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 frotp94d5q,b; wrxsp r (am ectotherms that have fluctuating body temperatur (rb; 5ptw4, srpxd9aqes?

  A metabolic pathway that convert,2ptq ;k pxc4 blcx+x6s threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes 6lqxcpbp+c2 xx;4,tk 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 rem d)8 nvwcjzp3se)x6.action. What is occurring during the phase labelled section X in xp 8s6.3jnc dm))ew zvthe graph?

  An experiment tests wiw/x d*2nkgc;hn9 q:the effect of changing substrate concentration on an enzymatic reaction. Whatn;ghw:92wdq ncikx/* could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to r*e: a6so2grt 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 activit6ldwq-2ks 0xq y was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) wl2wkq 6x -d0qsith 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 oeay1hq n no(k +j2nlh9; /zba0f the following is the best way to keep enzymes active for a longer period of timebh zoa1jk/ l9(e2yhqn n n+a;0?

  Which of the following describes some ty0 6cb 3 1cz,.wwjbfbsebjt(5 spes of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins0tp gmj1--3/ oumb sul to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant t-gut 03mou1 mjs- p/blemperature 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 7tur :41zj5( xoq gw4 6*n5a+flw-yujwzq tvlincreasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, angqyr j-a ut5:+onz14*ftqujlw4wzw 5 x6v7( ld 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 root into small cubs0z(hepc)n-3h8 pq epes. They measured approximaeqhhpp en) c-p(z30s8tely 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 esl53,-v +dg vrtpz i 6(-uvorenzyme HMG- CoA reductase can lower the production of cholesteroll(o pv vr+dt6 z3rivg-u- 5s,e.


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 inv8j3yiak6 z 4;p 3o jkkxvjk70volved 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 wero qmm-pe7t3am 2)q6lcmm cg84e given an experiment which demonstra lcm4omc2pq6-mma 37gtq8)emted the effect of temperature 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 efficiency of lvp;/ aox5* s vo efiiyuc9)62km t;we9actase activity is tested. Whi )ws op5te*x /v ;ue;yi69f ci9avmko2ch is an appropriate dependent variable for this experiment?

  A study has been conducted r0t0jgz f fsh s8 ,d+93q4hrvlon the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concen+z,3vq0d 4 8jh l9gr tsf0shfrtration, 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 v4udohl(8 /a g/3mupoox ,p.afor treating patients with malaria. Describe how anti-malarial drugs are beinup4 op3ad/gvx( mo.l/ ,huao8g 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 wtdx6 :j++hem 5bajh 0qcrb86*h(2a r ouf rc+affects the rate of reactim2c5jf0b+ rcj6ah8uq:b a+hhr6 o*x+tr( edw on.
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 d6vy0gdn)5 p 0hl-u:pq ru ei4jown or synthesized through metabolic reactions. Which type(s) of mpjyug)5iu hd0qrn 40e6:vlp-etabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can x tk+d6/ut w*kbe measured. kt6d/u xk+w t*
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 reaa4b(idgo +,gyf*es.q+ lh )r gctions, given one example of each type of*h) qgb +rdgy(+ea f, .logi4s 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.