Which of the following macromolecules describe a t,;f/btro ax8)fy 9d;7dkeeu; 3-4nhbq rimj eypical enzyme?

  What type of reaction is photo+mc:m7+jvo eosynthesis?

  What is the substrate for the enzyme lactas;**o uq(6 ckbbakj,f ue?

  Which of the following stage8xwd)i /at dt,s of cellular respiration takes place in the cytoplasm?dd8 t/t w),iax

  Which of the following would not be useful in determini/7as *8 3ol)zalawozj95c4r ev+hqu*qynur 6ng the rate of an enzyme-catalyzed raru)n3o q8/q+vy49as7e6rw *lo*lj ac 5zzuheaction?

  Which of the following processes may be described as c x5x 7v gk(p9blg3lkl2atabolism?

  Which of the following statements is best depicted by the kq3k-ja; h2 txfigure below?

  Which statement about enzymes is notcy/.+mge ;n+ aty4 firha 6gd6 true?

  Which of the following s88jm zl) mtr pq6eb.(graphs best illustrates the relationship between temperature and thser6jp 8mb8)q(l .mzt e activity of enzymes such as lipase?

1.Sketch a graph to show how incx dw. 42-nc07xkw xwcpreasing concentrations of substrate affect enzyme activ 4xc nx-wwx w7d.kcp20ity.
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 o5n sz50a:5m pe+wpa(gympzp0 utlining the Calvin cycle is s(ppz z:y0nam5w+s5 5p a egp0mhown below.

The image below shows the catalytic site of an enzyme. +j8c9kd6xreo+w2 jbfbwm00k The substrate is shown in black and is bound to wke mk2fjowbc 0bjd6x+r09 +8the 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 metaraj 69yz+ls pas;qvj q 02)y0ep4n ip+bolic pathways shown below? Letters represent various products of individual reactions. 0;ia4 pq9++sp2n rev6q zlajpy0) syj

  Which of the following describes the role of inhibitors in enzyme-catalysed kch4e9.t 5e zbt;:e lwk01nwe reactio.l50 bc w;z etkewh:1kt4e9enns?

  Which of the following correctly describes photosynthesis or respira.ycc3 k+u3 b43arslq gtion?

Many enzymatic reactions happen at*ivma v6jqfw6n up-b8 41ch 5s pathways involving multiple steps and multiple enzymctmaq p8ifv4bw6n-*65 j1 hvues.

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

  Which of the following best bqu ts1yd;zoqrs: ;r -a1*al (describes the inhibitor in the image below?

  Which of the following statxnwdp/tx 9k:g/j0n5n ements are true regarding regulation by end-product inhkxnjd n xp0ntw:5//g9ibition?
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. The darkel5/jm9q(:g7rgfjsj uned structureu(jr57 jgsjqm g f:l/9 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 study the effect of tempeh8n j8m6kjpyyvo1vg 8ud33e 7rature on the activity of the enzyme amy6 7mpyen8ju1jh 38do3vk vy8glase.



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 substrate*vhn 2ucl9:bws to catalyze reactionsv* u:nwhl2b9 c?
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 catagt :prnqdlq c/x ws.)* s8,i5klysed reactions can be measured.

  How does denaturation /zixhxdg3br o x, 9-g mm274y/qosrw) change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statem2 1rim,wrgmk6ents ari m1k2rr6gmw ,e 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 end(j kzu yv5*lnn) r(,vbotherms from ectotherms that have fluctuating body temperatures? vyl n (z,rk(bu*5njv)

  A metabolic pathway that converts threonine to the endz h61 n7c6j* s0eebfkm-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by*jzef6e1cnk h07ms b 6 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 e(oxc2z+bo xoi7 1wmi8nzymatic reaction. What is occurring durin+c ob mi21zo7w(ox8x ig the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate conn imx0j9 ,0u9uom; zgkcentration on an enzymatic reaction. What 9m iuo 00jxn z,9gm;ukcould be the independent and dependent variables in this experiment?

  The diagram shows the pathway th 1fj7xssiw 4k7at 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 zr j nieo*p +uel(09vaa0m(k-7ujlxipn8+z:a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-axis).z:9lz00 iap8l(+uj+ir-pj* n( vk eam ue7n ox



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 bcnre0k1.mr(a h .ax ;the best way to kee(e.0x; ckr nh.m1arbap enzymes active for a longer period of time?

  Which of the following describes some types of extrace6* wj4i5p/k 1rt hu32i ,hbrz or8wwbvllular enzymes?

  The enzyme pepsin hydrolyses proteins to releaseqff:a5p9t -vq 8tn3wy peptides in the stomach. A study was carried out to determine the effect of increasing substrate concepvy9:58f n-twqqf3ta ntration 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 reac uqnh1f,a tcq *qlw014tion 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 reaction*04qtn u f1lcaq w,q1hs. 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 turakx442tlj7 8p u68fnpvqs ,chnip 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 the liquid extract was stored in a test tube at room teqlh k47an pf6jpv tu 8c,2x48smperature.


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 enzyme HMG- CoA redn f80( t-te eu*v(6hn:j bb7;cqv bgvuuctase can lower the productite:v-8nvbhtj*uq vg bn 7fc6;0eu ((b on 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 denatux2 kg fq(,r;tbration?
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 cla)m /maxma3j0blz-+c xzha1- zssroom and were given an experiment which demonstrated the effect o -1m)zzxj 3a0a-x/hmc a bmlz+f 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 effec ,,fg wh1dd d rn6+/2zfow,tzrt of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable f,2h ozd f6,dw 1/,rrz+dnft wgor this experiment?

  A study has been conducted on the activity of avh-47 67aq2bo5 u rfnv fribcq5 fjl/9 specific lactase (Bg10), analysing the effect of pH, temperature andhqa4lin-7 rr/5j6 2 bcuv5o7fb 9f fqv glucose concentration, as it may potentially 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 treating patients6y efus8q (v8o: b7yl b:hrc/v with malaria. Describe how anti-malarial drugy/fr 67el(qo 8b8ycbuv vh: :ss 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 concenayq;go( t-w: ptration of an enzyme affects the rate of reacw t;o:(q-gpaytion.
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 dowbbl5u ho)dcx1iej43, we f z+r1 p0w7cn or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation reactionr, )ce 1pwio3c fb45x1bw07el hz udj+s?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed1umvgog1t/a5 jl9pl cg j;.9m reactions can be measured. v 91p9gg ;l5oltcgam j/ .1umj
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 dla. zh7e:wy0 ( tpvk;intracellular and extracellular chemical reactions, given one example of each type of reaction.d7y:(hk ze0ta .pw; vl
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.