Which of the following macromolec1kjjeui 6 *u3lules describe a typical enzyme?

  What type of reaction ipwhu).9mr kukt:. jf )* p .s-lynr6tys photosynthesis?

  What is the substrate for the ez 8y v.6whv 39likin sbpa1f20nzyme lactase?

  Which of the following stages of cellular re7fl5.w/jjw5yuw np +-cz :9oa f vva6espiration takes place in the cytoplasm? c6 j u p.evnw7o/5 al:w+-fyv9fzj5wa

  Which of the following would not be usef:jd p :/k+ru,ve9plgt ul in determining the rate of an enzyme-cjv r::t 9u, ke+ld/ppgatalyzed reaction?

  Which of the followinge n1y udqx+wi4ulj/. ;p eyf;9 processes may be described as catabolism?

  Which of the following statements is best depicted bd fb+/m(zsg* ,9c(b fmsfn*nfy the figure below?

  Which statement about enzymes isz*88g2 fnalqxvpu9n+ not true?

  Which of the following g7 2ryx *ws7g9w qi+sgjraphs best illustrates the relationship between temperature and the activity og7*j s+9ysg2i7 qxwwrf enzymes such as lipase?

1.Sketch a graph to shour ksx +az+h*v+:e 1txzd)f4bw how increasing concentrations of substrate affect enzyme)1+v4ezrs++b :kxt xf*zuhda activity.
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 diagra 9 jj0gy2xt0*b63bbz cm0t isfm outlining the Calvin c6zm2j* ij00 bb03gs xy9bt ftcycle is shown below.

The image below shows the catalytic site ogw:dd5c01 i6j xv:dl of an enzyme. The substrate is shown in black and is bou16 xddwglj::co05 div nd 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 catalydwc3(tq l; 0udsed metabolic pathways shown below? Letters represent various products of ind(q t;u l3dw0dcividual reactions.

  Which of the following describes tuix) 1 ms7shc, l8pn)n0rqt1ohe role of inhibitors in enzyme-catalysed reactinq8x srs7n)o1u ),h0m lcit1p ons?

  Which of the following correctly descry8qq/vq-u *h (4 a 7cla n7ay22mqw xl-vvgkp3ibes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and muc2 e4w6g;rd0f uryl(qltiple yg;u(0wd6crl4 r f2qe enzymes.

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

  Which of the following best describe jomu:rv:d-gm *miw-u) n1cf)s the inhibitor in the image below?

  Which of the following statements are true regarding regulation bks -s.t i1(wiahww1*n y end-product inhistw1 w.h(kiw*s1ani- bition?
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 djasa lr9o+-)qz :;nulysozyme enzyme. The darkened structure in black is the substrate and is bound at the active site+unqo ) -j;zr9a:s dla.

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

The equipment below can be used to stud dbuieo r)z.ah q9i bqs;.z+0(y the effect of temperature on the activity q+;rqb ze(ua ) .o0i9dhizbs.of 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 statements describ xm/*c tbhyp((es how enzymes interact with substrates to catalyzt(( hmcb/*xp ye 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 catalysd m4it1f)+vj. s4bjj eed reactions can be measured.

  How does denaturation change the properties of an en,h*v4oe-wf p):jf as8vtu. xfzyme?

  Enzymes play a role in catalysing reactions. Which of the following statements aca:zbb:fk/at c-6u; wre tru:bz 6c t/k; aabc:wfu-e?
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 sl wdfr xp8y5)0q2u1ei eparates mammals or endotherms from ectotherms that have fluctuating body temperatf l5yp82)xqd1 u ei0rwures?

  A metabolic pathway that converts threonine to thelhm9 v11s11-nrl 4hmnqolo l/ end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converteso9o4q -1hnl1l/mmr l 1 hnvl1d 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 reaction1g i5b25efs*)dd k vfvy02z cb. What is occurring during the phase labelled section X in the gr2s 5b*gdi d2v 1v0)zk5 cbyffeaph?

  An experiment tests the effect of c/l k)pan8s::66 kxxigimhlw;hanging substrate concentration on an enzymatic reaction. What could be the independent and depena wlxnxg i )mls;/6:h:pik6k 8dent variables in this experiment?

  The diagram shows the pathway that conver9 *bt yi4n(k)c foav/rts 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 activity wphz0f 6a k8 77fh-othkn.4zslas compared with that of ath 76s7ha .k 8k0h4z p-lzfnfo free enzyme in solution. The graph shows the relative enzyme activity (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 thep)81t6m fb/6rg kqqy7xwx3g c following is the best way to keep enzyme)7wpbg1gx m 6yt/3rqc86f kxqs active for a longer period of time?

  Which of the following describes some ty *;rprz;5n muhyg5nm8pes of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomac4hbptp/lx s 4).f.1 eyhhube) -ogzp 0h. A study was carried out to determine the effect of increflbys)z- p)10/4 peop hgbh4x .hute.asing 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 lj; 6(wq3nc+v bt cd,senzyme with increasing substrate concentration. Similar concentrations of chemicals A, B3+,v ;nc j(l d6sctwqb, 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, pp/3byy d or,std;iguxj5 3l8i: t 53ga student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used ay 3itp tjsp3u,g/;8xyd db: 3rg o5i5l 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- CoA red1qy2:v)bvks-l )a r0ezgjmc( a -dg 0wuctase can lower the production ofksjl0zr0dvwa g 1q cy (e ma-g2-v:))b 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 involvexp;e9pg1oiei. 4 ow. rd 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 rewd joen,m2*+jactions in the classroom and were given an experiment 2+,j dw e*mnjowhich demonstrated 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 lavrc-srt(y j;6vzf5/o0d h+ qbctase activity is tested. Which is an appropriate dependent variable for this experiment? zc 6 t/hs0v5 b(rorfyvq+dj;-

  A study has been conduc avm98 oay8at9ted on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lacvoaat a m99y88tase 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 patie+e ti34 wd owwy5y75uants with malaria. Describe how anti-malarial 5ywda5+tow3iy4 e7uw 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 increasingw ms1ycr w )n:wh zi,cb0ew8,5 the concentration of an enzyme affects the rate of reactio0c8)e1imr5 zbw n,ws wh:, wycn.
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 throughf1vrj-4pyoivg /fh/ r .w; ;qq metabolic reactions. Which type(s) oog.i;ffjvy/4qqw;/ rr ph -v1f metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of en23x /x8w1vns hk+25sm(tt 5 iaj tkehqzyme catalyzed reactions can be measured.i5w8 (3th+eqkx/1nvs2j tth2askx 5 m
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 reactions,i;dpy22ci v r6 given one example of each type of reacty2id6r cp2;i vion.
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.