Which of the following macromolecules describe a typinrlk01dp y9/ lrc3 (mrcal enzyme?

  What type of reaction is photosynthescelxr rn b.0d1: 9t*9wyl( hz+kvcd w7is?

  What is the substrate for the enzyme lactasa*(2nr v, ye/(* il- efrp(xidze zqd.e?

  Which of the following stages of cellular ruwaf6 )/x:nses/ qbi :5+te raknrg2+espiration takes place in the cytoplasr+/+b/q5 ek6 i a :euswnx:)anfg 2trsm?

  Which of the following would not be useful in determxl,9 :9id w ph0/bpzngining the rate of an enzyme-catadp: wbhn9 /xl, 0gpiz9lyzed reaction?

  Which of the following processes may be described as cad:(i7ukm kstd,bf3*o t,3uib2:wjyd tabolism?

  Which of the following statements is best depicted by 6xc j t(/u dq(1+lx4mjmeyu626cxamgthe figure below?

  Which statement about enzymes is not tr pu38o.vi v2tdkrk,jm(l l08 diouc62ue?

  Which of the following graphs best illustrates the relationship betz9+.manj4 imq2.fc z-gz o0byween temperature and the activity .z+gyiq- j 4ozmfba0zm.c 2n 9of enzymes such as lipase?

1.Sketch a graph to show how increasing concent e8z5n/ytpd-orations of substrate affect enzyme activinyz5oe/8 d-pt ty.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzymeyji3 uiz62.ra catalysed reactions. A diagram outlining the Calvin cycle is shown be62 iuy3ia zrj.low.

The image below shows the catalytic site of an +ms3r(n maho+tjvb,5 enzyme. The substrate is shown in blackrb+ samo+, mj35( hvnt and 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 enzyme catalysed metab6 qvt ,y wc0s6ry pgsrr/y011dolic pathways shown below? Letters r qpvy, /0ys1ytrsgr drc0166wepresent various products of individual reactions.

  Which of the following desck :e;;(btfoat,ocqeo xp+:7e ribes the role of inhibitors in enzyme-catalysed reac pkoe ceaf: oeox tt,b:;+(7q;tions?

  Which of the following corrh ek d(ej13a bt2lf28wectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathu) aa /6ii)epb (xbo;hways involving multiple steps and multiple enzai ephbiabou)/( ) x;6ymes.

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

  Which of the following best describes the i.q;o z;g )liwfnhibitor in the image below?

  Which of the following statements arho(66s a3litkzgw7r: e true regarding regulation by end-product inhibition?7hg663lat:(ki szwor
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. b3 ql sesl(e0u8x*.;kpyov . eThe darkened structure in black is the substrate an x.blyekv0u;ploqe8s. e3s *(d 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 temperatur3vniqq*;/g dz nf-q.re on the activity of the enzyme amnd i*r-q/.nq3fv ;gz qylase.



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 interact with substyi:g wjj2r5er x5f-j h.2x8c rrates to caw5j g5j2h-f8ijrc: r er.xx y2talyze 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 catalysed reactions c*e 7 dca .j-(pl;weqckan be measured.

  How does denaturation )gjywi71.v m v0rq1nqchange the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following sta1+ +sajkvt(nq 7 mbw+ktements ar7(wqast+ +jnkk1+vm be true?
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 ;fjb+k5e( 10jc q;delxihnk :from ectotherms that have fluctuating bod: 1fk;5ijxkce 0bd(ejl+q h;ny temperatures?

  A metabolic pathway that converts threonine t3t*40gll*r5 xq cadyyxq*re r58w 9kao the end-product isoleucine consists of five reactions. T05**r xagk rqdwt9eq5lc84y a lrx3*yhreonine 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 increasi if k7n3v.1ik;mgs)rzk 6 lvp*d;7eufng pH on the rate of an enzymatic reaction. What is occurring during the phas*lksv1kgpf d6i3 77m; e vuzn)rik ;.fe labelled section X in the graph?

  An experiment tests the effect of changing substr 44 x2itzhm9qyate concentration on an enzymatic reaction. What could be the independenty q9i2ht44zx m and dependent variables in this experiment?

  The diagram shows the w*zyz.cy5*o,pa-ea /aw ,uft 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 matrix and r oex:/b)oxei:b *bveysj798 its activity was compared with that of a free oj9be/)yeio :b7x8s r*: x bveenzyme 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. Whicv+5c y g5eg8xch of the following is the best way to keep enzymesc+x 8e5cy5ggv active for a longer period of time?

  Which of the following descrimje bw14.*ify2.1fvf6mrc wx bes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides inz+)n)jt 0dnmw/oxsy n y 90,on the stomach. A study was carried out to determine the effect oy9 n)t0y smn0n jod+wxnz ,/)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 an enzyme with increasing subst6kc d.vs7xlilo 8 qp(sq0s 29nrate concentration. Similar concentrations of6n k9c 7lqsql.2d(vop 0ixss8 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 inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a turnip root into small cubes.fvsz*k ic 5q85 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 filte cifvz*8s 55kqred 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 e9p )nv7d;wp6gs . mjhanzyme HMG- CoA reductase can lower the production of cholestehpnw.vj6sa )g;7p9md rol.


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 involv6u727mz dffi aed 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 a hov-4f/f sgkf9rj53v nd were given an experiment which demonsrg593/h4 sffv -jo fvktrated 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 e5wvzbnbmyl02z,r+efq d en--q : 2yi0ffect of increasing temperature on the efficiency of lactase activity ieq e2:-+n m,zwyqdzbyv5 2bi fn-0lr 0s tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lac fvf/ pg1ez 1q.0nh;matase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to qmae vpnh1/. 1gzf0;fproduce 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 continuo a f/ tqpdfuig7ud5: v8y:.,gous need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with vy8iad ug/pq5,fg dt:u . of:7new 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 bmti9,*: 0 5fdvt hnwb;bm-c xthe concentration of an enzyme affects the rate of reaction w05dc xm*,vmtt:in9bb-;f hb .
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 metabo cn vu, p f *x30w:kksz,xls3);i.xfyflic reactions. Which type(s) of metabolic reactions are condensation reactkfxn:vf3zcxk.lp w;ix3,f,) *suy s 0 ions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catqwpvx i7,r5-zf. pp 9ualyzed reactions can be measured.zp.-w9pv 5 qfup7x,ir
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 intracellularjhh0m:9wh xhyipi5 .izi,j* q 80 .hgi and extracellular chemical reactions, given one example of each tji,gx0z0 :mpiy . 9hh*jwh h8ihqi.5iype 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.