Which of the followito4ph:*xj3(h ji0w +dm;t h xing macromolecules describe a typical enzyme?

  What type of reactio:a0)zw cp( ynyn is photosynthesis?

  What is the substrate for the byex5 (m1m s c9rhxgb 14ry8*zenzyme lactase?

  Which of the following stagc :0a2ujlpgdr u5v; ke6v(nw2es of cellular respiration takes place in the cytoplasm : 20wgv n eajd(;v5kucru26pl?

  Which of the following h pc)r4dwecz5:7e,u fwould not be useful in determining the rate of an enzyme-catalyzed re p: czf )cu7hree5w4d,action?

  Which of the following processes may be described as catabolis tyfb7/u gz(i-9jni2zisa- 99lh.lj lm?

  Which of the following statementakxfe x63ftr 9f 94(ods is best depicted by the figure below?

  Which statement aboutj +7ha+ukq u l:ky+6:+b6 /;c.oepsjzyontwx enzymes is not true?

  Which of the following graphs best illustrates the relationsumqw7hkc-8.r5 hs8c thip between temperature and the activity of e 758sctrh8m h uk-q.wcnzymes such as lipase?

1.Sketch a graph to show how increasing cn4i o733 ,hag3s6gdt/gkqtj xoncentrations of substrate affect enzyme acti3k7t4 3qtgigjhs / ,x 3go6ndavity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed )o. 9kg a-ugljreactions. A diagram outlining the Calvin cyclejga olg.k) u-9 is shown below.

The image below shows the catalytic site of an enzyme. The su1e opkukw8w(.i n6jz0zkl,) zbstrate is shown in black and8(,e6ku 0 pok1kzzw)l. zwjni 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 descriptionmy)hc.68 rqj6 dgaey1e*y +1 8sk d4t8dspnmus of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reactions)m1*nr6d1 yqs86 thjmsag e8u.cyed dy8 4+kp.

  Which of the following describes the r*7) zsxt4n k3 ob1mbaaole of inhibitors in enzyme-catalysed reaczm 7ts ko1)b baa3n4*xtions?

  Which of the following correctly describes pho g9hy ef0fn;/sf8r8 vu3tpr(/hi er .btosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple step ; ofiwhzw ibwqo,,2,du)6x,qs and multiple enzymes. 2q)d z owwi 6b,o, ;xwhfi,uq,

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

  Which of the following best describes the inhibitor in the ivglys6* 5 mn2( lsr9t 0cvmqb.mage below?

  Which of the following statements are troo ):4ykl prt3ue regarding regulation by end-product inr3ktoy:pl4) ohibition?
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 e unuejj0, uxd*c(l0l) nzyme. The darkened structurell 0,ejd*n x)u0cu(j u in black 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 stu:r9mwyn 5ajy;in .. klty ,;judy the effect of temperature on the activity of the enzyme amylase. .k:y;inywn.m j95uyjl;ra , t



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 s.hy4zy+w1h uf tatements describes how enzymes interact with substrates to catalyze react+zuy 1f4h wh.yions?
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 c4f*hu0e lt ld73*u h,fi)u egbatalysed reactions can be measured.

  How does denaturation change tpk x1qzbvr07 pdq-/edn8:h: ehe properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following sc/ -n,pcyec0 nij zyy/eh760btatements are np e-je0nb y y0ic, y6c7/ch/ztrue?
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 ectotherms m5ij)4x .k lx9 zqmb(mthatz5 .(mkj)9qmmx il4xb have fluctuating body temperatures?

  A metabolic pathway that converts threonine t dg*1j-xc.n:uq.ztave a(pp*o the end-product isoleucine consists of five reactions. T.njq .ed1a(ct upg- a* *:zxpvhreonine 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 o esr ,6a3xasgsm*0si23 jq/83z uz vwqf an enzymatic reaction. What is occurring during the phase labelled sectiqvea z8sz , ugs 3 6ws/ir2s3qa0x3*jmon X in the graph?

  An experiment tests the effect of changing substrate concentration on an en pt*5qlxgjq, :zymatic reaction. What could be the independent and dependent variabltq :5gl*j x,qpes in this experiment?

  The diagram shows the pathway that converts h doazo7+ z.o/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 its activity warlz k,hr5y(/ :uk 8vebs compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axiszb 5yukk8/:,h lvrer() 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 denm w oe,vb(dx0.atured. Which of the following is the best way to keep enzymes active v w(bme0,.d oxfor a longer period of time?

  Which of the following describes some types of extrzfr5p ) uksw;yyboc7zy9-u9 5 acellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stuuhy; 9) g5tl9-htpdp j6t;qgady was carried out to dettta9;ygp- ) 5q lp 69tugd;hjhermine the effect 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 with4t gdgtccft1b -8d2 )n increasing substrate concentration. Similar concent18 ttt d gcdfn)-42cbgrations 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 inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme xc6 (q*bv;tgn y7bn) wb3f) ckf0we8 ractivity, a student cut a turnip root into small cubes. Tc) k6*be; g(b rfn nv0yq8bxfw7t3)c whey 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 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 si p0 8,sczd3sshown below. Inhibitors to the enzyme HMG- CoA reductase can 0sidp 8c3,sszlower 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 involved in denatuqdy oyy+:/3+ p bndl7vzs91 nnration?
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 reactio ;u qu97utf-jqns in the classroom and were given an 7q;uqj -utf9uexperiment which demonstrated 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 effea( oppgsh91f*glg t20rrfi 9h1xg /,ect of increasing temperature on the efficiency of lactase activirrfiex g,thf gag s1h1p90p(2*9g/o lty is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conduclzqz9tgyykba 0; )y(whtvb8- y k+/0t ted on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be usz hy0/tyw)8 ay0(9 kttyk; b+zb -gqvled 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 treating patients with ma 3/itymn h:qss+ 7t4xplaria. Describe how anti-malarial drugs are being discovered with x4t3yqt/ 7 :phsmi+snnew 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 /; rv9 r0lac ut3r6qahenzyme affects the rate of reacrtc9; q/v63la0 haurrtion.
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 brokeozzamfh+ 9 z i*uv-* s)me-7yr;l)nrdn down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are+rz*a;rszy -9ef -mlh )mv izuo)7nd* condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions ca jahn0urw(kjj-w92,t +:mx mun be measured.2jrkn+ mw0j (u,j twx-hu9 a:m
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 rzw ,fjst4xm;d g)9+ )9ltgmxceactions, given ;tx)s),+4j g9wm dc9gxfztm lone 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.