Which of the following macromolecules describe a typical enzyme? a89k.). e5ylvmecigj

  What type of reaction is q4j-4djbi - qrphotosynthesis?

  What is the substrate for the enz 7rtzgv b1z;7z/ rvke0yme lactase?

  Which of the following stages of cellular respiration takes place in the b ukj7k0vxgu8y8rzxv+( 5 (ko yt58 jacytoplasm?5 +05 y uabvk j8jk78(x(t zovrg8uykx

  Which of the following would not v.w*xf4sybg g8g ;amwcq-w8- be useful in determining the rate of an enzyme-cat 8vxgw*ywb8 -a.g-q m;wf4cgsalyzed reaction?

  Which of the following processes may bevsu6 f w9xqp.) iwye eox5p57, described as catabolism?

  Which of the following statements i 9o wdz;*pgv(krzws;9s best depicted by the figure below?

  Which statement about enzymes ia -3wqujhsep y 8r1s*/s not true?

  Which of the following graphs best ib*c iwkl s72 5wmdi6wj0/c3ynllustrates the relationship between temperature a3y2i nbw/ s *kimj7dlc6ww5c0nd the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affts0*pzc:ld h1 ect enzyme activityzc0tlsh* 1:pd.
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 diagram outlixs *e .u-0jnf8u f1qtmning the Calvin cyc-8.mu*se1j x nqf0tfule is shown below.

The image below shows the catalytic site of an enzyme. The substufnwz- iad lv.1:704 tybqe.xrate is shown in byd el-t: w.1 fzvu70b4xiqa.nlack 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 descriptiwobcrnqn2m2;p 7- q; tons of the enzyme catalysed metabolic pathways shown below? Letters represent varp2m nwo 2;-btq7; qncrious products of individual reactions.

  Which of the following descrij .b3c* lr)ztubes the role of inhibitors in enzyme-catalysed react brju)* clzt.3ions?

  Which of the following correctly describes photosynthesis or respi:arzgy1h4 m .bration?

Many enzymatic reactions happen as pathways involving multiple steps ans1f 6 g1a6 li;1(/rj8eajmtoped1 svb d multiple enzyme6dae(lf6ov1r1gmps1 s /j;a8b et 1 ijs.

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 below:jw(zc8 oqz* c?

  Which of the following statemenzb i8uy (9 wlf(oft0y7e9y r6dts are true regarding regulation by end-product inhib7( 8r bf u9fyoi0w9y(l zydte6ition?
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. Tzaj+,oy ,1-v r szwe*uhe darkened structure in black is the substrate and is bound at s+,,jvr1u-zyw ea* ozthe active site.

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

The equipment below can be used to study the effect of temperature on tt2dd xu7; zoeym22r oqo(8b w)he activity of the enzyme 8umtd w2 y) ;dx7o 2ozro2(bqeamylase.



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 enzymes interact with subsx enry dq-klr ko+*sq0pn6pgq(:3 9 g:trates to c *ppd03n:n+q xq lgk- (r: okg69syqreatalyze 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 measuredz4ub)be n7hdft:( o+d.

  How does denaturation change the properties of anp9xi3l*. k h-y c6ntid enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statemenma7aem 3-8hwmo/q9p xkaw: i: ts are true /qiaw w39x-ea8:mm 7kmaho:p?
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 characterih8tgm o;zr( u7stic that separates mammals or endotherms from ectotherms that have fluctuating body temperaturez8h(muogt;r 7 s?

  A metabolic pathway that converts threonine 3/dn(lrp0:v z:1nu r- pcovi oto the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isole ro-o(z1/ cp0rvdi:pnv:l3un ucine 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 ream;u u v4 +7m3,btqlf4.a;uqz2a5ax rzg2 daphction. What is occurri+. 7 blhdpmz2u3v;4atxau2a5 qaq4mf;z,g r ung during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentratxt9*gpky2d2 )luodb 88 sq;ufion on an enzymatic reaction. What could be the independent and dependent variables in thu yopud)x8t2k d 28gls *9;bqfis experiment?

  The diagram shows the pathway that converts threfuohla0( rs s,f893c qonine to isoleucine.



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

  Enzyme A (Enz A) was o(djmgt47v ): r3p ydpj4.o amimmobilized 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 ma jjdy)pvrop:t4gmd43 7o.( 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 fo bq-v +6fybvu(llowing is the best way to6yv qf-(v bu+b keep enzymes active for a longer period of time?

  Which of the following describes some types of extracelby)/mjuru.swxp)e i 5w1, ut2 q1sxw 0lular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stud6b aml/fkp* aq8;mbq,q8ndr ,y was carried out to determine the effect of incq r* ml,,ab pbq8d;/6kaqnf m8reasing 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 re05eqgqv i7xetlz 8 wvq-rt 0;f6bte2,action of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, Cx 6qi 7eteq-z00 fw8gvlvt;5t erqb, 2 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 cut9fblv1wts b1 9 a turnip 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 was stored in a test tube at room temperature.9vstf1b b9w l1


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- CoA reductazql3;vm0hxbl;i8 39mby;lqv c * txnj,lt ;e-se can lower the production*cl; y xt8v ;lhz -bn3vblq;jmt3, x;e0q lmi9 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 5w s5.g5rrjsqdenaturation?
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 reactio 5 -agoxt6cc14lrvam* z:odevfs e,66ns in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolzlem v*vegsdo1:- 5c 6o466tx crfaa,ic 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 on5 ;pib 67om z4bg4ux1 gt3gitt the efficiency of lactase activity is tested. Which is an approptgtu tz go454bp3mi 1;b67gxiriate dependent variable for this experiment?

  A study has been conducted on tzk 8w j:lq s9u5p .kjc;7ej8bbhe activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose kj8bj we: jkb8u5z s9.7pl;cq 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 treating patients with ma,d wwe2vl+ t w2+wsy 3tbt99jplaria. Describe how anti-malarial drugs sd wwvytwt2p3l2+9 9j,t+ ebware 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 increasinglnm2u a2dd2isj8qe0 l s,7a/x the concentration of an enzyme affects the rate of reaction. e7 d,n282 jd qas/lxl2mi0uas
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 th+s *3fr yu2l m ,f6r-i6uflpbw8jmfh*rough metabolic reactions. Whic6r ymf-2uipms3ff8f6b,hjl w+l *r*uh type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rjc9(xqcfg 03 wate of enzyme catalyzed reactions can be measux f0gwjc( 3qc9red.
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 e uou9 umiob4(/xtracellular chemical reactions, given one example of each uu(om9i/4u ob 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.