Which of the following mac.heh f5bv47b2i.i0sdqxw 8r2(upg ykromolecules describe a typical enzyme?

  What type of reaction is photosynt4 6 7b*holtg0s9 iwgmchesis?

  What is the substrate for thekh+l:amor*g (q-b yq1 4uac+q(7fg q p enzyme lactase?

  Which of the following stages of cellular respiration takes place in the crarm:b xyu -c91(0 ipeytoplasme0rb icmu1 y- x9p:(ar?

  Which of the following would not be useful in determining the rate o2yx+r m )re(ffb :9a +h;eironf an enzyme-catal:n9f +oyr ) ee(ifhma;br+2xryzed reaction?

  Which of the following processes may be described as catabolismq)7 6polh:hlb?

  Which of the following statements is best depicted 6t,jo (q9xdgr l bb9g1by the figure below?

  Which statement about enzymes is not tqfbkqjcrl90 qi.8. )zij0b:x rue?

  Which of the following gr2hyd3snim9v4-oq wu 8aphs best illustrates the relationship between temperature and the activity of enzymeq ydw3h smnv2-o894ius such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect en/nm1v8odz c 4szyme activi z4cn1ov8/dm sty.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactions. A diagram outlinin0agm972d):yd m;o m jrfwup7ug th au9d0;gmd 7)u mm2p yfow:jr7e Calvin cycle is shown below.

The image below shows the catalytic site of an xtyo;ys9* *pqenzyme. The substrate is shown in blackt;*y*p so9 xqy 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 descr zl loivu a1-c8z)t43u(ac( jziptions of the enzyme catalysed metabolic pathways shown below? Letters represent various pr- 8c(lta )4zlauizj 1uo3cv(zoducts of individual reactions.

  Which of the following describes the rtela 3 aul,77dole of inhibitors in enzyme-catalysed reacau 73,de llt7ations?

  Which of the following correctly describes photosynthesis or mr/fvq5o kj58p *o:basm m6.irespiration?

Many enzymatic reactions happen as pathwh74mea 6o6n 4gmo45ps .vscjqays involving multiple steps and multiple q6m6 .ova mcp 5oenjs474hsg4enzymes.

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

  Which of the following best describes the inhibitor in the imagy7lskn2s qc4 3e below?

  Which of the following statements are true regarding regulation by end-product xdctv:(nn0c y)xc-( e inet-cnx(cynx (dc 0): vhibition?
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 e /hah9j;np* clysozyme enzyme. The darkened structure in black is the substrate and is bounah9 c epn/h*j;d 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 activeb1f )yuhudnaz87g .cb ( .pdfl;.mh) ity of the enzyme amylase.(.cdlz.)u yh8b1. ;nhgafeupmf)7d b



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 int.em9 u9uea zn7z hhc,)eract with substrates to catna.hzu ,9u 7)che e9zmalyze 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 reacs*jk+p*g9m(josl 3cu tions can be measured.

  How does denaturation chang9t.lx d5 k )o7zfl;pcle the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statemennjjk xh61l4 jax: t-z4wt0 r(hts are truew (6xlj4jktj0 n z-r: 4hx1hat?
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 characteristd+(,tyn( wwh4i i(6crag-ss fic that separates mammals or endotherms from ectotherms that have fluctuating body temperatusywha 4r(c i -isdn+t,(f(g6 wres?

  A metabolic pathway that converts threv+ b4,tzib v ;,vy bot,bzz1h8onine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is convobt4bz,8yb; 1z ,izv ,+hvb vterted 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 eg)1wqpyt hh0.l*lze*nzymatic reaction. What is occurring during the phasepeh.h* ) t1zll* qgw0y labelled section X in the graph?

  An experiment tests trsrd6b,u 32nt jps5 0the effect of changing substrate concentration on an enzymatic reaction. What could be the independent and deptsu,s prr 5b0j dt6n23endent variables in this experiment?

  The diagram shows the pathwaiwahq58m: 1 a;lton6 n(rm4lxy 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 5e11u n 4hms+ vjzdyti lx;; fwtclc+s-2o25i matrix and its activity was compared with that of5 vidhc+tf2lw n;x5j; i+ lo4st 1mu2y-se1cz a free 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. Whichjv zmzg+877+ sieqs.db 7ukn. of the following is the best way to keep enzymes 7nmz.zuji7 +sd qbgvkes8 . +7active for a longer period of time?

  Which of the following describes some types of ext r;bf7d6jyzp9 racellular enzymes?

  The enzyme pepsin hydrolyses proteins to re7 uwor0mhv2 :+sil ex4lease peptides in the stomach. A study was carried out to determine the effect of increasing s xvl+is 0:h4 7wm2roeuubstrate 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 reactionzj x1j*b3sk4 m 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 t3b4xsmj* 1jk zhe 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 tz x5yi em3.,6lp jj:xnurnip 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 tjnexl pji. 3yx65z,: mhe 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 enzymqegmy y2jts eg0, n33:e HMG- CoA reductase can lower the production of choleste2qm0,eyygn33est : g jrol.


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 d;fiee76a jxk9x( mru 2enaturation?
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 remd3 c,u,;wj-0x ez(ie npt8poactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reactioneu jid mp-on8 ;xc3,0,(zwte p.
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 temperaturb;nn6dzm4m z o,(7xsve on the efficiency of lactase activity is tested. Which is an appropriate dependent variabl b,;znxo mzd64s7 v(mne for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10)25ttbkoyrrk91 o)kf1n:j0 q o, analysing the effect of pH, temperature and glucose concentration, as it may potentially b: 0kobqt)59kjt1o 2 y or1kfnre 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 sjd ez z2(* ks72gf.;*3gumgx8xa8)mgv xfxa for treating patients with malaria. Describe how anti-malarial drugs are being discovered with n2fs2ekgm8g 3juzx*s.(*m8 fg )vzag7x ;dxx a ew 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 the raa4txz 3 mhq6h4fi3bv +te of reaction. hqb x t3+z4haimv346f
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 metabolic rea6(+ro jq sb;2qvo ka1yctions. Whic 2 y6r (soqaj;oqvbk1+h type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be /npwn ud .ck(+ d)a6dhmeasuredkn.ddd 6+pun(hw a/c).
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 intracellul:u-09zg vghhgar and extracellular chemical reactions, given one example of each type o-gzg:g h90 vhuf 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.