Which of the following macromolec *ib(zo5jn2.bepmno w /f5poa r0/,p iules describe a typical enzyme?

  What type of reaction is pho9qjjxpji+ b.oy. ) uh/tosynthesis?

  What is the substrate for t 6t-, . as0ip vucm3 ahv1rwe2:m9rgtbhe enzyme lactase?

  Which of the following stageefa2ujb l( e)k11stf9 s of cellular respiration takes place in the cytoplasm? k lafj9)11eu(2 fbtse

  Which of the following would not be useful in determining n.r)8s+afrz rqj 52okn4jro ,the rate of an enzyme-catal j)8a2rozrko5,4 n.jsfrr+n qyzed reaction?

  Which of the following processes mvn4j+w;f y1nv5kn )fday be described as catabolism?

  Which of the following statements is best depicted by the fiqecat:too -8i, -4xu sgure below?

  Which statement about enzymes is not true nj1 +o6opfit5 herbf aj9yv8e2mz;pq9p;n76?

  Which of the following graphs best ilma3 l)4y0nvk qi -xg6alustrates the relationship between temperature and the actiknai0-v43 lg6a yxmq)vity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate af o( 4tnb.pqko8fect enzyme activi8.t( oqbop n4kty.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a f-ia -mijj3g0gpa. 4eseries of enzyme catalysed reactions. A diagram outlining a.0a- mf jiig4g-e 3jpthe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is s.b(8 mq ay5k xz7h3zqfhown in black and is bound to the active site. aqz5xmq3y fk. ( zb87h





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 pathwayht2tqb7 1krs g g :u-yor1oh3*s shown below? Letters represent various products of individual reh7uyor *-sg2r g1 :bhto1k 3qtactions.

  Which of the followinor gf vgm( ja,5ynjnl*/.cnoe/j3(4s g describes the role of inhibitors in enzyme-catalysed reactions nr*nfjl4ny3 cgg 5( s.,ajjom //evo(?

  Which of the following correctly describes photosynthes;.c5k62 m8wgx hz ax4cvrkii .is or respiration?

Many enzymatic reactions happen as pathways involvinan f1+jxga;, 0; vlnulg multiple steps and multiple enzym+a v;n ,g01;jxu lfanles.

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

  Which of the following best describesep qkh v(:i na7sk.88sgc5kz6 the inhibitor in the image below?

  Which of the following statements are true regarding regulation by end-pro+ x- -xlh6gbphduct inhibition?hb +hg-x-lxp6
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 da: lo6tbmnp)1 wde c26b ez8itz u1yj-,rkened structure in black is the substrate t: lo6i uct1bpe-1enydbz2m z8j w6,)and is bound at the active site.

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

The equipment below can4r5t 57 jkr1absphcr1 be used to study the effect of temperature on the activity rj1c5bsa7 5r14phkrt 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 describes h2gpiy :3czz 6zb0grz7ow enzymes interact with substrates to catalyze reactib3z:r ggzc62izy 0 p7zons?
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 catix m a+,fv1q;ialysed reactions can be measured.

  How does denaturation change the propt 4u8 *b rfgtmx;rl2v+l1aj 95j6dxpverties of an enzyme?

  Enzymes play a role in catalysing reactionykeo tv25 ,sk+s. Which of the following statements are true5 v, etkyok2s+?
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 mamm5;y ex xlz6y:y: .zexaals or endotherms from ectotherms that have fluctuating yxlz zy;::5 exy ae.x6body temperatures?

  A metabolic pathway that coez6k(n1qbpi 8hae5i6(rc5 2grln:.g p7h maanverts threonine to the end-product isoleucine consists of five regq:a2ba6aer.p(7 5hp5e n1(k i6cnzh mi r8glactions. Threonine 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 enzymatlhlpu,5 agk .3r6.u hzo)bj3,cgr k7wic reaction. What is occurring during the phg5. lbw.c ) 7hk3rz l,uo 6kr,pjag3huase labelled section X in the graph?

  An experiment tests the effect of changing substrate concent2ggwalm(1:iex9g*v . j uk. xhration on an enzymatic reaction. What could be the independent and dependent va9( .mlki gg wh1exg2avuj.x:*riables in this experiment?

  The diagram shows the ,ejn8wn854iglasy * i pathway that converts 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+y i4*:o yrlb9hh3n +exksb8z matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme ac3+x8: ho4skb 9iy*n+b hyerzltivity (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 thdqwn(o0q t 2.l/eux: l 6+bcjle following is the best way to keep enzymes active for od+ (xl/6nqb:e2wjc.ul lt0 q a longer period of time?

  Which of the following describes some tyu k npzfpt7j76su6/p+5x+.k v;i xpfw pes of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in-v7ou -wblba 5 the stomach. A study was carried out to determine the effecolba -u vw7-b5t 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 rea+x vp:.vyk7:dq ,h zaj gz-ea;ction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monitored for each of the reactioagdj7e:zx: qzpa,h y+vv ;.-kns. 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 actvn0:(i4 ge5p;ir7dt 5tjc wd xivity, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water andet icjn5i:(4vd;p7grw5x0 dt 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 enz:7ovy 8h0h nq- f0oi9np4unnqyme HMG- CoA reductase can lower n8007oo:i9fq nnh u v-y ph4nqthe 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 arelmx;rhv-r 27i xa36hg 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 reacti pg7vtyb,mflt9 q0hl .g3s2kpk28/ t bons in the classroom and were given an experiment which demonstrgl /m2th98 pkvylk3b7s, b2tg.f0tq p ated 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 h ee/nw-41tr athe efficiency of lactase activity is tested. Which is an appropriate dependent variaw4ra1t- enh /eble for this experiment?

  A study has been conducted on the activity of a su) xe9gu+ rg4j2gux8o pecific lactase (Bg10), analysing thexg248+ xue jurg)9guo effect of pH, temperature and glucose 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 treatin+(r nnxxh7f8k g patients with malaria. Describe how anti-malarial drugs are being discovered with new technol8fr 7kx+x nn(hogies.
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 enxb/+ q70 -alc;sznjgwzyme affects the rate of reaction. jb 0;z+-l qcsaxn/7gw
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 syntheuv4uu64 nir7y*o,gh-lf b0 u rsized through metabolic reactions. Which type(s) of metabolic reacti,ruih04lgun*ybv6r- 4o u 7ufons are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyojn)7(g t /t*r*dxhzks/vt7vme catalyzed reactions can be measur7vo/ *(g7tz *njtk)/x tsdrvhed.
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, giveay9y:,hrrl;j oi77yzv9ht8 rn+cg:yn one example of each type of hyyr;ty7nrv:og,jcyr+z97h8l a :9i 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.