Which of the following macromolecules describe a typical enzyme? qb 2(d nfg;/o*n+ajwb

  What type of reaction is photn,n)e-/ x k1if ax.qmrosynthesis?

  What is the substrate for na+ig0bo,k /llya/+idb g. h/the enzyme lactase?

  Which of the following stages of celluft) lx*3 kjg4ylar respiration takes place in the cytoplasmx)lj4gk tf*y3 ?

  Which of the following would q 3-k5dt-w-lafpxje9xp;-6 ;wzhfyfnot be useful in determining the rate of an enzyme-catalyzed reactdjwkef- 3l- pth6z5wf;y9pxa xq- -f;ion?

  Which of the following processes mk 1bos5adjn4h4 pz*o* m :dm7iay be described as catabolism?

  Which of the following statements is best depicted byc-3i7v ory0o g(j kkz/mz.r-b the figure below?

  Which statement about enzymes i9k3kvw in 0;kscn/w1ps not true?

  Which of the following graphs best fz)f b25z hwe*illustrates the relationship between temperature and the activity of enzymes such as hzwf5)*fb2ez lipase?

1.Sketch a graph to show how increasing concentrati9cij * wtey+* yv*hf-qons of substrate affect enzyme actv9t* y ey*cqj-wi*+fhivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series ofj:k gvfoe8m8g( sqmddpw z:+,7se5w7 enzyme catalysed reactions. A diagram outlining the Ckdp:q:wj5 s(g7s78z mgf od e,m +ewv8alvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The subspy2jcl b f*m-/trate is shown in black and is bound to the 2y -flb/jmp*cactive 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 d)w* roa8qnp;below? Letters represent vari); dwap8*rnoq ous products of individual reactions.

  Which of the following describes the role oft0zuh;w ylgkdv79q1 2 inhibitors in enzyme-catalysed reactio z9wu lq7k ;h0tv12gydns?

  Which of the following correctly describes photosynthesis or respiratione,lzymi ;c,6:c(vgbeqfrmxl)8u7v c4ie *i 9 ?

Many enzymatic reactions happen as pathways involving multi7czy z(4hh2xdyuz:rtkj7 3v 0ple steps and multiple erzd:7kz 0jv2 thuhc y734(yxz nzymes.

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 begmj:2mafwav/7p0d8j i4q dv 9low?

  Which of the following statementfe6n+ n niue )d-z;p)cs are true regarding regulation by end-product inhibi ez ;+nucpf) n-d)ein6tion?
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 ofy;8*yj ze+kqq 0uj xo8 the lysozyme enzyme. The darkened structure in x e0 y8jujzkq+q8o;*yblack is the substrate and is bound 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 on the tetsu cf0d73gf40v e0activity of the enzyme amt f3 0vc70dtgues ef04ylase.



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 inter-m:iq/a t*zli(* zh eoact with substrates to io:a* (*z /qi- hmezltcatalyze 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. ntx*m5 widz.m/ym7e catalysed reactions can be measured.

  How does denaturation change t0v4 u.66gaoevi)r qylhe properties of an enzyme?

  Enzymes play a role in catalysing reacqrl ch:9 cg5i2m*c k;ctions. Which of the following statements are truhc5qcmcg9c; i :l *k2re?
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 thlkd27)v/ilc+5yjh1xnsv3 - ti o:xt iat separates mammals or endotherms from ectotherms that have fluctuat5t:ny2ki 3c)l x+ti- sovid/lv1jx h 7ing body temperatures?

  A metabolic pathway that converts threonine to the enpqc2( axw3wk+ 4j8 btld-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleuc w xplk3j2w8t4c(b q+aine 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 re 8/b9 6msvuhiwaction. What is occurri smh/i98u vwb6ng during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate *ji/* gkl ;f2 y)uwpizconcentration on an enzymatic reaction. What could be the independent j;*/w i f2zl)y*ukigp and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine zxo3ale /9,/li3u xwt4 cehf ew (*lp0to 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 matrfnb3- rzon gwpd). kw /pt3qr:1b; ro,ix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme actfn.;p-/3,b 3n dorkw g)b1woqr:p rztivity (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 denatu+xdfg,m)uchddp0 30 l q;;hgqfy56wx red. Which of the following is the best way to keepchxmg+ w u 3d,g)dyq;0;f0 pdq f56xhl enzymes active for a longer period of time?

  Which of the following describes some types of u+v/+lyln, flszcomg,c 0*si 436 6tya 5bm xzextracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stu a/jvc):qds.ab s3) 3jj2b lu3j1kshw dy was carried out to determine the effbcj.j qw2 halb )3/dsvjju 313s):k saect 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 reaction of p7rn;- ti ;p4o 3ph6c2rc2tksf:qwe yan enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independeyr:4f2p c6n ip7c2ets; ;k p ho-t3qrwntly 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 wf-)qirgyz3l m+/g .2 vehwf+cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added fgeqfhg/w.- i+l2 rvm+ )z3yw50 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. Inhibitorqmhai8 fydv-1l zmtq -15 p.)js to the enzyme HMG- CoA reductase can lower the production of cholestd) p.mmjh-v8-1y qiftazq1 5lerol.


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 involv7pppa pb8qp06b f8nbv.g 8 (fmte4pi4ed 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 reactioheh tsv6 ,l* n bc9t,1lue*3gcns in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reactio*1clhtblegesun6c9 h,,t3*vn.
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 temperaturelwcv c,wofg7 pq6c97 afqe*12 on the efficiency of lactase activity is tested. Which is an appropriate dependent vaeq 9cv7 ,cc 1lwg*2f7qo6apwfriable for this experiment?

  A study has been conducted on thebky t tp :)w/-9w,-oxqoua4 bz activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as i,9wo-)-4youbtbz w q axk/tp:t 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 f -a.*j mhtpe:a6 :j u(fgnq9.dxr bqt/ind new drugs for treating patients with malaria. Describe how anti-malarial drugs are being dixahq*:jfqm.t 9b.u:6(pn-ga jt dre /scovered 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 concenazs c6+5xc;0,os sn83 anesze0 ou-d etration of an enzyme affects the rate of reaction. 6 o0 ,szns8 od-50zec+ ;nxacaes3use
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 synthesi*x l(ya.fouc.+ egnt *zed through metabolic reactions. Which type(s) of metabolic reactions are con(.axtl c+*.uy fgo*endensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catal k/n ocx3db/5,inn0zmyzed reactions can be measurexk,i nc//z3o nmbn0d 5d.
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 extra6mit5 kv p/,uxvkd( f2cellular chemical reactions, given one example of each type of reactio,( vpxfdu/m2itkk6v 5 n.
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.