Which of the following macromoleculwke 18oc4z ntj2l6(boes describe a typical enzyme?

  What type of reaction b j*uzr:,hi*wdutf i.8b(ql+ mafs1 2is photosynthesis?

  What is the substrate for the enzyme lactakkg.j(.9/fqz :ah ekhse?

  Which of the following s144ms 0jr4mvxyt 1yv btages of cellular respiration takes place in the cytoplasjy4 4xvvmmr4sy 0bt11 m?

  Which of the following would not be useful in determining the rate of ans y85p)ml1nbd.c cdj 4 enzyme-catal5lb.c8sm1dn y)jd p4cyzed reaction?

  Which of the following processes may be dpbs4z *q-mi1o8rk +dtescribed as catabolism?

  Which of the following statements is best depicted by the fx y5zyu7hc e2+igure below?

  Which statement about enzymjd*2q*x w uqe*0 3 gy)jef1z /d6qmfqbes is not true?

  Which of the following graphs best illustratrz6,a tggf ga q) m::c8do;.qves the relationship between temperature and the activity of enzymes such as lipaseo:zvct6 rqa8 gqd;:.afmg),g?

1.Sketch a graph to show how increasing concentrations of su. xye;9gt ;4lvwurg-2d nw hperh4;t+bstrate affect enzyme act4; ;+rhdy v 9e .grnut-twle4;p hgw2xivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of en- qw1 oclw)a r8) i+hup:;rerzzyme catalysed reactions. A diagram outlining the Calvin cycle is sh) q h wl8ora1);ziwpr e-:+urcown below.

The image below shows the catalytic site of an enzyme. The substrate is shown in)9w/n eg 8lfpi black and is bound to the active si)9 n8gi/pfwle te.





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 metabol;74ybvd; qy2ksrt/ clic pathways shown below? Letters repr yc; 2t;brvk7dl y/s4qesent various products of individual reactions.

  Which of the following describes the role of inh ox8xen3.j 8j whb-a.xibitors in enzyme-catalysed reacti -xnhj8 8xae .b.3xjwoons?

  Which of the following correctly describes photos qtkxu .;x-k64mod+z+ejet6k ynthesis or respiration?

Many enzymatic reactions happen as pathways invoa-mnrp3 p,l.k 8xu+aplving multiple steps and multiple enzymes lu.-kapp3+ampnx ,8r.

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

  Which of the following bej e; m-dnd 4xv-de k*i)8r0wha0ruj(zst describes the inhibitor in the image below?

  Which of the following stateme-) 58z m5h3o-livfhwe qxr mling*j 4,nts are true regarding regulation by end-product inhibit3 jhwn-gl i 5z-8i5 me4lrmxv)ofq*h,ion?
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 08qj8nzc/4oj yfuz3ro0 ec 8vlysozyme enzyme. The darkened structure in black is thofcqen/zjo0zy8084c rv3 uj8e 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 temperatu(rv qm04 (wj k 16z;mro2yefenre on the activity of the enzyme amylase.e04o zrnmmek fj6wy(;1qr v 2(



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 intera;-cpldu )bckt)72v jl ct with substrates to catalyze reactions)clv)b-7 l jd2;cutkp?
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 canj9:qt:w ,4cvm/c ely1wep/ w k be measured.

  How does denaturation chang*yezibt :qr s9m7yhc p)j d391e the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of 5th/siofj7yv *y4 : ggthe following statements are tr yy/5:gt vs*gi4ofhj7ue?
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 mammals or endotherms from ectotbrg/v te, a2c6yne:d (herms that have fluctuating body temp/a,:t y envercg b(26deratures?

  A metabolic pathway that convenoo/21p3dz pa+9bf* hfos5 y 7aven5 qrts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is se7bof5z+*o5 3a92y1nq/f onhd pavpconverted 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 reactios 2 e(ksul4du1n. What is occurrslkus4ed(21 uing during the phase labelled section X in the graph?

  An experiment tests the effect n,q *q +*)ramgtji uil-2vde,of changing substrate concentration on an enzymatic reaction. What could )lm ,tq ga,i- d*+eqjur v*n2ibe the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonin f yvotbgide)blf o)4/* ;-;oje to isoleucine.



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

  Enzyme A (Enz A) was immk;hh y-gk4,*p r2omstrnrzp21y zm0-wfc;5fobilized on a matrix and its activity was compared with that of a freh tzr-kf ypfrm05-k;; ywnpo41*z2 2g s hcm,re 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. Whichapwf5uux6lcbb2+kxzemxn ;2w-3n3 2 of the following is the best way to keep enzymes active for a longfanuxx wk5n2pm3bw6;3cb2-e z x2lu +er period of time?

  Which of the following describes some types of extracellular enzymes?;.:czd.l zf9a(9 o drvbg fr)u

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A sw7efik eg 9:a.tudy was carried out to determine the effect oiwg9. e a7kf:ef 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 t) /8h8uu pnzxdlpj e*bf61h4hhe rate of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicn1p6b8/eh)uh*jhdzlf4 8pu x als A, B, 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, a student cut a turni hgfz1hj/7l 2jp 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 liqgf7 jz2 jl/h1huid 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 )nhx 1s)wg3bpderk8+ the enzyme HMG- CoA reductase can lower the production of cholestedrhsxwe) b1g k+p 3)n8rol.


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 al,t4ki+ mj(ja,e+6j iu;:h cb+ yctnwre 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 classroom and were give p7vf hl0lk*7ifu, e2qn an experiment which demonstrated the effect of temperature on a cat ,v*kq u77pie2 l0lfhfabolic 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 thl/ ug*1fxo ha0yi1- nhe efficiency of lactase activity is tested. Which is an appropriate delg*1 ya/uif1hoh-nx0pendent variable for this experiment?

  A study has been condgr nf 7p bs5/-lko7/vsucted on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentr/v5s k /r-7gsp7fnoblation, 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 treayg3mwvc 851qk4n mv8j ting patients with malaria. Describe how anti-malarial drugs are being discovered with new technolog kwmyv3581v8jngqc m 4ies.
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 en99d(xi+s)rbbwh u ku +kv0* bizyme affects the rate of reacti v9rbb+bw(0*i9+ihx uukds k)on.
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 throu.oae dfq.gh44t2 nwoto+ y 07gprrd78gh metabolic reactions. Which type(s) of metabodg+4n7y4o7o re g r8.fhtwaq to. dp20lic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of en;2v.f a+pwb;b8hp liszyme catalyzed reactions can be measured.pl bb i p;hwa.8f+;2sv
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 extracellula uj q,8 mk:8n9c56wp5(pe)zezowf iiwy vd:) zr chemical reactions, given onzewf:mw9q)uijpy8: np5(oecz 86wdi5,)k vz e example 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.