Which of the following ma1vv .jrd: 9efpcromolecules describe a typical enzyme?

  What type of reaction is ed7u4abu7oo8s.l0p w rr z;8aphotosynthesis?

  What is the substrate for the enzymeb6 .jsy.nf 7at lactase?

  Which of the following stages of cellular resf5)8ud nc4b3my2cl j ypiration takes place in the cytoplasmjfblc c y8 u5yd)42n3m?

  Which of the following would not be useful in determining they.r 5,*d o(jug(xgq z 10gfwjm rate of an enzyme-catalyo gyrg 5jdwf mz0(x .1qj*gu,(zed reaction?

  Which of the following processe0ie-orayb ipf plno)4-4 6zvhv.8 hf(s may be described as catabolism?

  Which of the following statements is best depicted by the figurt 4 oq+wwv.df1e below?

  Which statement about enzymes iib2nq03qf e igqxtj21 , iyh5(7xi5aos not true?

  Which of the following graphs best illustrates ucwrs et)t:5:ab9a.9 kkmc e2the relationship between temperature and the activity of enzymes esm r5:ab u:)aec2kc t9w9 .ktsuch as lipase?

1.Sketch a graph to show how incr2 fn*diwoli/ji9z;5do . ( q0vvo:zmkeasing concentrations of substrate affect enzymldozoii v(zj5:i9nd/ k;o fw. m*0v q2e 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 rexp8 o t;9wpz 0,sgy3doactions. A diagram outlining thep90g xy;p8 ,oo w3tszd Calvin cycle is shown below.

The image below shows the catalytic site of an ekjejx9p0 w(/ww/5k3dgm lit ( nzyme. The substrate is shown in black jwpxkd gk (t50(e/j w3 il9/wmand is bound 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 eneo7( 2qx na7nmzyme catalysed metabolic pathways shown below? Letters represent various products of individual reaction(mn2 xqa 7one7s.

  Which of the following describ(+9oc jv,ht- 2 5imo06tzr-rap gelpbes the role of inhibitors in enzyme-catalysed react -, m(getr5rlbt v6p o90i+ozpajhc-2 ions?

  Which of the following corujsrpn ya5 g4 2 : 8pyxqtavsr4.q3u07rectly describes photosynthesis or respiration?

Many enzymatic reactio90p4fj s bcp l40a8uq9j uhf-bns happen as pathways involving multiple steps and multipl-90afpsj0l8buquh p9 4jf bc4 e enzymes.

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

  Which of the following best describes the inhibitor in e/fw xdk3a0tc6i9 c4yg( zym* the image below?

  Which of the following statements are true regarding regulation g5*:bgar+eg( io ii.+lr of)aby end-product inhibit )ig++ro lo (ii:* r5bafgga.eion?
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 tq71uh;:t4d,oe)y bc 6tp qlvbhe lysozyme enzyme. The darkened structure in black is the substrate and is boun,tvolt4c: qq)1b;d6he7 pbyu d at the active site.

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

The equipment below can be used tov b2auwi y* y+zly29ufp9mm: fjr.3z * study the effect of temperature on the activity of trbyw39uzfm pyuf vzl:.22**j y9 i+ mahe 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 kst7n5,4f1ha7zhki7 eu b 3x3f7jo tlhow enzymes interact with substrates u ia b hkz737h,3e7l 7ts1 kxf4fn5jtoto catalyze 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 f q+dwf4 u, f2wc6;calcatalysed reactions can be measured.

  How does denaturation change the propertm / edg*;cwmn:3egjr7ies of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the folz+c2 1*q1t eak(t bxttlowing statements are true? (2t+tc1b1t ktzea q*x
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 characteri-:lbdlnn 7r2/b ky w -l ,bni79bnwi-jstic that separates mammals or endotherms from ectotherms that hav/nwn-n27byrb bi-dl lbwn-j, k :9i l7e fluctuating body temperatures?

  A metabolic pathway that converts threonine to the e1jrfp*5c4 m lehotq lx,b91( and-product isoleucine consists oo5l cm9*rtl qhbf(4 p 1ex1ja,f five reactions. 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 ofvwd4r-o . -,qvh;v e/sj eg6og increasing pH on the rate of an enzymatic reaction. What is og.wj 6h ev/qd o-re, v4-;ogsvccurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentra px-umpjhnkgc4-h(4icux ) 3 +tion on an enzymatic reaction. What could beh 4c4kxp uhcxu-pgimj 3+n( )- the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucina qryzk34gd+.e.



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

  Enzyme A (Enz A) was immobilized on a ma.)7b;k1 7 *kij pwyok:cjy zg21bu vohtrix and its activity was compared with that of a free enzyme in solution. The gra7cvbz7o ikhgjpw 1o 2ku*; )j.1:bky yph 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 d mq2en l5 ,s05zv9qoqhenatured. Which of the following is the best way to keep enzymes sl2mno q z5eq59v hq,0active for a longer period of time?

  Which of the following describes some ks+ 7*lq3 ;jolyzarkj :4dq4 ltypes of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in tu c a bfu,*mm*i*o2kf-he stomach. A study was carried out to determine the effect of increasing substrate concentration on e*f uobamfc,ik** 2m-u nzyme 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 showshpcszd )x4;4g the rate of reaction 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 reactions. The curve marked A coincides with the activity of the enzyme with no inhibito dzp )h4gx;s4cr added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, iy,b rip/0r,pbm-kk k1t).ibvm4lr 6 a student cut a turnip 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/kyv,rk 1-0p6)t,miim. i kbb rpbr 4l 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 be 7d2l.u0opoc lg5p sf2low. Inhibitors to the enzyme HMG- CoA reductase cp7og5ps f2.u2lcdo0l an lower the 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 are invole2 j-mo,b2b)iryhn5)svt 2x m ved 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 reactioni:, gp.i qna3 4ttefn0s in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic tnt eii,0fp4q:.ang 3reaction.
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 increasingx s*t an q0zi4so/:8gg temperature on the efficiency of lactase activity is tested. Which iss zg:/q0a* g8sxnt oi4 an appropriate dependent variable for this experiment?

  A study has been conducted on the actyoli + 5x;2 rx/dgqk.jivity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentiallgi rk yxj;o lq.2+x5/dy 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 trea/ut9gwp6k,msb/ )m isting patients with malaria. Describe how anm6t) gubk9iws/p, s m/ti-malarial 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 increasing the concentration of an enzyme affects tn0bgow48jl8d;h qs;q. v 6j.u o bb;gehe rate of reactio;ql8qghe .;sw6ujb;o o b8vjg0.b4 dn n.
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 metav5; tqt;v7bpx*sszltc2 a+b 8df d3m0bolic reactions. Which type(s) of metabolic reactions are condensation s ;dvb0;ts5fbad28p*7 mvxt q+ctzl3 reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways tbdr8aclh.sv 7l;p sec5 *+) i4vznnq 1he rate of enzyme catalyzed reactions can be measuc vzdas7bceph v .s5*nn8 r4+)1lq ;lired.
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 anj cv (awa uby ufff:2 r(jb0a*ti:0224aoh.eid extracellular chemical reactions, given one exampl bb:ue 0iui*r 2ht.20afcaw2 :yja (o(f vj4afe 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.