Which of the following macromolecules describechzb7 9f, 8u1faq7bzj a typical enzyme?

  What type of reaction is photkuyh4 exes zve +um v8)-r3b;-osynthesis?

  What is the substrate for thes0.:knu9mo de enzyme lactase?

  Which of the following s(2 c xuh1)3a e-qpczirgsvl32tages of cellular respiration takes place in the cytoplas2 1 -eqc2 u(vc3r3gl)sixzpham?

  Which of the following would not be useful in determining the rate of a7 (uywqvt,;yg9 is jj2;g 5sxy v):gmmn enzyme-gy5mvx;jm(i:yts ;)2v,j qg7w y ug9scatalyzed reaction?

  Which of the following proce1,wru9h :dit 0moz:pusses may be described as catabolism?

  Which of the following statements is best depicted by the hp(2kcf, frx1k6rd m8o nr /i:figure below?

  Which statement about enzym o(rmk1i5i rhr6o) 0ages is not true?

  Which of the following graphs best illustrates t**),3f+xa vghvdae no he relationship between temperature and the activity of enz v3 evo ad*ng),faxh+*ymes such as lipase?

1.Sketch a graph to show how incrt(egi (a; sh,heasing concentrations of substrate affect enzym,h; ghsei(ta (e activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalys 7t3nl: vfux5-vme -xoed reactions. A diagram outlining th3 mfvnu7 l5x: t-v-oexe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The svclnf3u 8*q 9r7 v ou5lg2jsu;ubstrate is shown in black and is b23lsjnu;uc ufq*rv g8o59v 7lound 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 enzo2s0x i p/udo o,hcj92/1mv r kkyvq(-yme catalysed metabolic pathways shown below? Letters represent ykxu2sk2 ji vd 1r-,h9c/ /o0op (oqvmvarious products of individual reactions.

  Which of the following describes thexh;ka f2i)4le kfr)7v role of inhibitors in enzyme-catalysed reactions?lf7h) vkaf ;24r )eikx

  Which of the following correctly describes photosynthesis or respirmv5qzt8 4qmz;z*/q t yation?

Many enzymatic reactions happen as p+p1y e(0gwkjz/8 gb9omw+blq)gv l j2athways involving multiple steps and multipl/g op(j 2b+l w+evg qwb1)8l90zjkgy me enzymes.

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

  Which of the following best describes the inhibitor in the image below : n(gmpbelyay spgqt((y ,3+)?

  Which of the following statements are true regarding regulatioqj+2o (ms ad:mn by end-product inhi+(m dam :2jqsobition?
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 ofb .fb5j sszl tgy /wq0k/xb/8- the lysozyme enzyme. The darkened structure in black is the substrate andf./5ybwgxsz/k /sj0tqb8 b -l 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 temperaturegi9oai 68. fb5zt 3qkjal b3w8 on the activity of the enzyme amylaszi 3tq8b96 li8 a3g.k5wfjaboe.



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 80sbs ug.slvm y8 2vlqro )m56substrates to catalyze 8vm 5r uls8lm6v goq0s.2b)ys 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 enzyj )f.k-ikc2d vme catalysed reactions can be measured.

  How does denaturation change the prop54ow: 8 tx ja0k8b1zc9aerffs :r /tpzerties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the followinu*b8 c p*mv3;g;noiombbacwg0tv(rh d +7w04g statements are tru8+prtu0gcbo07h( b*m * 3b mc ;gv dvwi4wna;oe?
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 mat rzqy+r6.hoto 1zh* 5xfh98fvd ,wb(mmals or endotherms from ectotherms that have flucrz th +6roz 18f,bx*t(fdqyvhw5h. 9o tuating body temperatures?

  A metabolic pathway that converts threonine to the end-product imq 2f -x3xhwl83)zpqu 3e8ury soleucine consists of five reactions. Threonine is converted to v3m q8f8xlqwyxh -puue3r z32)arious 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 rat.mb qg(b q+vb1e of an enzymatic reaction. What is occurring during the phase labelled secq.bbqb 1vg( +mtion X in the graph?

  An experiment tests the effe,5cmvg;nb q5e ct of changing substrate concentration on an enzymatic reaction. What v n,c 5b5emgq;could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine 4po 6flf9p .5,p35 klmszqkacto isoleucine.



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

  Enzyme A (Enz A) was immz0h1+pj58 -qw iyphhid kt8o-obilized on a matrix and its activity was compared with that of azot q hiphh1-+ j8dp58wk0iy - 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. Which of the following is the best /hukfo35*j ege*g ;hp way to keep enzymes acto e*3jhggh/u;k5pe*five for a longer period of time?

  Which of the following describes some types of extracellh:hjo5 d6zgw6lgt* *e ular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in tt qdx1it+k1f 3ygrw0*he stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a consta3t1 xy+wf rq0*dt1 kgint 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 en,r sxp rn,-v,zzyme 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 xp rr ,,s,n-vzenzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activitx2/g. d/(za i, pfxjgiy, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing g/ip. (,x2i jafxz/ gddish, 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 pathwaybtjb6a2zob qct 9 rus2;6;yr/ is shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholesterolbu 62s 2 brrz6bayqt ;tjoc;9/.


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 denaturationlja;.axka*34zug f nvx 8ax(: ?
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 reactib;n/m4eghsl1+ph 2;eb ttnv8s g/bl+ons in the classroom and were given an experiment which demonstrmtn81+es gs/bl2;bnlth4/ h ep;+vbgated 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 effect of increasing temperatukr96 ;pb u9jmhre on the efficiency of lactase activity is tested. Which is an ap;pkj99bhur m6propriate dependent variable for this experiment?

  A study has been conducted on the activity o :fr,hqv 2wpkgl: ,. laygmje+qy+aq7e l1(k2f a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used aslh2 v,q:mrq7q: k al 1.j2ee ++gpywak(lfyg, 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 continuo :s25wrzhbr7vzz +uk5 us need to find new drugs for treating patients with malaria. Describe how anti-malariark7 r2 +bzuh:zw5 vsz5l 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 increasin2ytgejcc c98 .g the concentration of an enzyme affects the rate of reaction.29gyc.tc8 j ec
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 metiy)kiz yt- c6,abolic reactions. Which type(s) of meti,tki-c yy)6z abolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different wa niwxf(8-sj5t ys the rate of enzyme catalyzed reactions can be measux ( 5wjni8fts-red.
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 and5 :vxo 5.bw jzk.,s/zn5qrf/hrt8xwh extracellular chemical reactions, given o. ob8kstwv .z h5r5, wxhzrf/:x /5qnjne 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.