Which of the following macromoleculesd*t6mic xlhsgh 3wv4 7 ww1s63 describe a typical enzyme?

  What type of reaction is p6 quvqxu-eq5-xgf/6(m 0dvit 5, ss eihotosynthesis?

  What is the substrate for,ak0 rt )ld9ha the enzyme lactase?

  Which of the following stages of cellular respiration takeb .ub9u yi)id+s place in the cytoplau9 +.bbdiy )uism?

  Which of the following w m-2 x:(dfng.qtrt t3)l+rpfjould not be useful in determining the rate of an enzyme-ca rt(xr-f+p:).dg ntt3l mqj f2talyzed reaction?

  Which of the following processes may be described as catabolism;z al e(nd6yud(a7to rp)*8rd?

  Which of the following statements (a;w+4x r o .eqc:rkqgis best depicted by the figure below?

  Which statement about el 49rrdmg; o7n2y+xbs sl.tx 0nzymes is not true?

  Which of the following graphs best illustrates the relationsmt: bf(wa: wk/hip between temperature and the activity of enzymes such as btwk :(wm/ :aflipase?

1.Sketch a graph to show how increasing concibi onkb -0b0.entrations of substrate affect enzyme activity kiinbb bo0-0..
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysec4)p9 y/azlkn d reactions. A diagram outlining the Calvin cycle is shown below.zykclna94/ p )

The image below shows the calelb6s; kh,v4:66b:gcjw i9jvd ( gqgqdn/* ktalytic site of an enzyme. The substrate is shown in ki;vl :b*,9j6q6dw(beg jvh 6q 4dckl/s:nggblack 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 mze4 6 myh q 62azd4o;ijamj p);f)p1tketabolic pathways shown below? Letters represent )) ykjfo;i6te4jpzqda m4ap;h6 12mz various products of individual reactions.

  Which of the following describes xs5 ;gwn ug30lthe role of inhibitors in enzyme-catalysed reactisw 5g3l;nxgu0ons?

  Which of the following correctly describes photor7sf 2g)hjjt vw4:5 smsynthesis or respiration?

Many enzymatic reactions happen as pathways involving multipl *kvd4;jz0edke steps and multiple enzymevde k*4k;0j dzs.

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

  Which of the following best describes the unu s/ug,:8+s.9ecsr9-bpsd6f o gq ginhibitor in the image below?

  Which of the following statements are true regarding regulation by end-product es* bpaoha-lj2v d8*0 inhiv l*adhosbpj20* e8-abition?
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 tfs l-8 ,udf)kpr 0*(wc9ba mabhe lysozyme enzyme. The darkened structure in black is the substrate and is bound at the act f8s,-lk(*b)dubc0ma f9wa rpive site.

Which of the following characterizes the active site of an enzyme?

The equipment below can be used to study the effect i chtr3wpj264 of temperature on the activity of the 2 4ciwpj hrt63enzyme amylase.



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 enzymesi q9/ w-addw(xxk.s am5o1 0uh interact with substrates to cath95xuqk ( o/dwa-diswm0a.1xalyze 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 reacti (8 prn iw*mfg1tdz-i(ons can be measured.

  How does denaturation change6vczhp 7ps55 t the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following )9qdm(.frtbros9 d u8 statements are( 9f8m. qut9dobsd)r r 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 mafrteqe50 fnm6pgfuuwa*w8:(h: m5 9j mmals or endotherms from ectotherms that have fluctuatihpfa5uegfm 08 :wnqmr6t5:ef wu9 *(jng body temperatures?

  A metabolic pathway that converts threonine to1ewvnm2hu0 ,i the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme 1m 0uwniv h2,ein 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 enzym8m3s7h9j ryw 3ubgja(atic reaction. ua 7jwsmj3r y3g(98bh What is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing sub v+yw m f(,br 5)qg2s;ftown3fstrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this experiment? v5,ftnr3bm sq +wg(; 2)yfofw

  The diagram shows the pathway that converts threonines3 g9dhz(f7k l to isoleucine.



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

  Enzyme A (Enz A) was immobi ml6 jz:w)u,ntlized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis,m6)wj nltzu :) 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 easilbahy22 ek,s-w y denatured. Which of the following is the best way to kwheyab2 -k 2s,eep enzymes active for a longer period of time?

  Which of the following describes some types of extrac- b u trueu*h7yq.)ki6ellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides 331e )gqad qpj;g 5fscin the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant g q1 g3dsfqe; cpa5j3)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 subxnh jfe6ogb 7zr0f 3m) ;c/gt3strate 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 reactions6t/r zc0gb nfm733jegx) ohf;. 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 ll8/znlo +/p dktt+z4cubes. 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 filt znt+k zlo8d4//t ll+pered 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 enzyme HMG- CoAo0n374(ywr.o qiz)pj9e fr rg reductag(wz93 yief74o.nr r0)poq jrse can lower 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 o z*+lh 6dnk7+i8xqkbare involved 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 and were give1 *l uc)k/r fziz0xv)zdhm gon48+i/fn an experiment which demonstrated the effect of temperature on a z*i)oxn1 h cd+f4 mvf liu0 z/8)g/kzrcatabolic 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 temperature on the efypu w2y,1b ts6ficiency of lactase activity is tested. Which is an appropr by2tpy1, w6suiate dependent variable for this experiment?

  A study has been conducted on tggij c- 7vu/ 2 0);v gw4js8wkzhkoag9he activity of a specific lactase (Bg10), analysing the effect of pH, temperature a7)aj/jg20g8s-w o 9k;vh iczukgvg w4nd 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 gylj5kq sef/ k.w(/ h9to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with ne.sq//jeyf 5 k(hgk wl9w 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 k b1/vjsv zr ann )(,7)h:rsz-.hlyol an enzyme affects the rate of reactrlk1- )y v no)zvhrz hblj7: (s/.a,snion.
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 reactions. Whic(r6 vlab9ohi* h type(s) of metabolic reactions are condensation reactio(va*l9o6 r hbins?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed cl63m/ma v7cvad-k dftb+6 7hreactions can be measured. kfva3bl7avdmm c/+tch6 6 - 7d
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 / blf:e -lqhn8,;lnbl and extracellular chemical reactions, given one example of each type of reactio; ,bf:lll/hq lnbe 8-nn.
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.