Which of the following madq8ksnbwt w3.wq 69;0svhs e: cromolecules describe a typical enzyme?

  What type of reaction is photoi 2rzhv.2vkav 3kc s 1fpk,ssbc 4(0bu4 2x0risynthesis?

  What is the substrate for the enzoeni9 b/ 1*whxyme lactase?

  Which of the following stages of cellular respiration takes place rhj i (mpk31r5awws-3in the cytoplasm?ir1p33(hwk5 rj w-sm a

  Which of the following would not be useful in determining the ra:uz5/aqt( 5dbfu- dw jte of an enzyme-cdf (bda5zq: w5t- uj/uatalyzed reaction?

  Which of the following processes may box7vf0.,z4 +uduci i4s7hgvzr 5id yft9u +z ;e described as catabolism?

  Which of the following state6,dorsz:n* yo+beo8a ments is best depicted by the figure below?

  Which statement about enzymes is not x fu z./+prh0f2nu y;01srjbytrue?

  Which of the followin 647xw-i ++ enjfmdnuig graphs best illustrates the relationship between temperature and the activity of enzymes such as lipas-+ 4wim7j+ x udin6nfee?

1.Sketch a graph to show how increasing concentrations of substrate kad1fk4nm 1 6kzekxd3m 5t,+aaffect enzyme6,nf1k4x3 a kktzmm k1add+ 5e activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series o7qj fe51mnq+u t,7.mvn92vn fl7x h 4c6djymqf enzyme catalysed reactions. A diagram outlining the Calvifl 21+q ex c7yvnqnumh5,d6q79 fv4mj.7ntm jn cycle is shown below.

The image below shows the catalytic sivzx,.pqdwg)h cx:c 0 ,te of an enzyme. The substrate is shown in black and is bou v,0dczqxgpw ch x.,):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 catalysed metabolic pathways shown rug w q5 zomf:l(9v+x6below? Letters repr(uf5xz6lqo v+gr9: wm esent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed reacy(h,jy-op s8p tpjs p-y oy8,(hions?

  Which of the following correctly describes photosynthesis op(fxx (/vuk* xosy y)yg0 v;k) )bwt5pr respiration?

Many enzymatic reactions happen as pathways involving mult1ga .)ak ax)r.yi-emgiple steps and multiple enzymes. ae1gaa -)ig).myxkr .

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

  Which of the following best descri:a0ad,dqn ,:lhfpjrn28q t d5t+o; kkbes the inhibitor in the image below?

  Which of the following statements are true regarding regulation by end-productub+ .ii*vr+ gc inhibition? +v.ic ib*u+r g
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 str7-3k) aa zo in//monjjbuj6k,ucture of the lysozyme enzyme. The darkened structure in black is the substrate and is a/nu7ajmk,jbo- j kio z) /63nbound at the 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 onp i n;w;s+go8:1kq hih the activity of the enzyme ahnws ;1oiqi8+hkp; :gmylase.



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 describom :( afoi;/vnjo1e t0 gs5c,ees how enzymes interact with substrates to catalyze reactions? /0(;fe iogn5ecm ,tj1o:o vsa
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 reactiof7 g u,:am9,onw qctov h1)tz/ns can be measured.

  How does denaturation change the propert9 y+ c o-jyys7pni trnp7()f4qies of an enzyme?

  Enzymes play a role in catalywn5pyd /p +(c15zplda d,8 byqsing reactions. Which of the following statements are tyw p,8/5+5ypc dl dpn1qaz(b drue?
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 j9jvu2 pj;sfbjte 071nug-9e separates mammals or endotherms from ectotherms that have flujujvj;utps19ef n-07ej 2g b 9ctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product isu zpznn9 2;2rkoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by differen2 r ;u2zz9knpnt 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 *49i lkw,zodhenzymatic reaction. What is occurring during the phase labelled sect* wl9i,zk od4hion X in the graph?

  An experiment tests the effect of changing substrate concentrat/tbz7r1b(hh- vxs(f afu *lh 4ion on an enzymatic reaction. What hr/(uzb (hx1*flh f-a4s7bvtcould be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucycrb71xs*z d+ fi ;+rieoze.4ine.



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 hroa0r) mhk 47 +od:iiactivity was compared with that of a free enzyme in solution. The graph shows the relative enkrri)0h 7di+4aho m o:zyme 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 denatur p.x9bzg*es;lln ;p*oed. Which of the following is the best way to keep enzymes active for a longs ; *gol.e;*pzpnlb9 xer period of time?

  Which of the following describes some types of extracel1w-lkicq z en7ilr zsjqm,a-/.e 99h9lular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in thehe:w2;ao1h -a cacu x.bzf9(t stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperature.9z ;fboh-ew 1a2:ctcu a(x ah 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 ratwb1ph2wui*ha x-l x4. e of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were addh-2wxuixa41lhb * p w.ed 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 st+xda;r z0*z epudent cut a turnip root into small cubes. They measured approximately 5 g in a zarz+e;0*dpx 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 enz9k 9qm*be s)(s og: s8pb(i4zf7tv ubjyme HMG- CoA reductase can lower the production of cholestero qo9gzj9fusbp(4e( st s7i*)bv :mb8k l.


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 b* a6lx800b:z kvsiuz are involved 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 classrooqumnn8p *e8 46g/nyga m and were given an experiment which demonstrated the 8un6 eynpn /agm*q8 4geffect 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 d: dk;a)e yyx;of lactase activity is tested. Which is an app ;yye :da);dkxropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analysde rpp6o:.5v 7z7injk ing the effect of pH, temperature and glucose concentration, as it may potentially be:ondr57p e7 k6v. zipj 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 treaoq)jn0td78v w ,ger :no/spz .ting patients with malaria. Describe how anti-malarial drugs are being discovered wiw 87 negqo0vrd)/t,jznpso :. th 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 enyj)5.yozabb5 *c;uvb( s5 nauzyme affects the rate of reacnu5yu.ay5;ov c*b )sjb zab(5tion.
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 reactiovj4d:a +x6l3w:n oq vsns. Which type(s) of metabolic reaction3jdl4:swo+ a6:vxqn v s are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalj nwon.2*bse6) *jy*3y b2rtmf)u cmqyzed reactions can be measuredm)m2tj q.b3 eb6rufn y2 **jy)wcon*s.
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 reac( hzgy z* zf0-phs 6g8,b+krzwtions, given one examp ,y-gprs8+ kgz( fbw6zz0z* hhle of 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.