Which of the following macromolecules describe a typical enz(9 /9vcwad45p jq qiumyme?

  What type of reaction is photosyntheh-yvr xyt3hbp 92;qxo 0ea7w6sis?

  What is the substrate for the enzyme lactase3(mln y: xoas5?

  Which of the following stages of cellular respiration takes place in the cytopl hgm7 6e*la4mce.4mg tasm? em4*lm 6.meg47gc tha

  Which of the following would not be umi5an *k+,d:hy mlc)nseful in determining the rate of an enzyme-catalyzed react* +hc:nnik)madm l,5yion?

  Which of the followijbld2m( a s)p2ng processes may be described as catabolism?

  Which of the following statements is best depictedua *; +iec.0t: z; y2ubomngyc by the figure below?

  Which statement about enzymes is not trues. 3fpdes8;t1c 9 xg/eia/unx ?

  Which of the following graphs best l wzj0:vs;gw wm.v9)i illustrates the relationship between temperature and tww jm0zvl)g :is;9 wv.he activity of enzymes such as lipase?

1.Sketch a graph to show how increasing conceg2kq 7u ba0sw)ntrations of substrate affect enzyme actuq)bkaw 07g s2ivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a seril* nedgnj wv3,*9ivl+es of enzyme catalysed reactions. A diagram outlining the *g ndi*+llw 9v3 ,vnjeCalvin cycle is shown below.

The image below shows the catalytic site6 fvwtl u1b6(k+5*v zqaq/m tq of an enzyme. The substrate is shown in black and is t5vq6qtmwbuf*z6kv/+1al q( 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 metabk6noj8xozm );a c2s/xolic pathways shown below? Letters represent various products of ind8socmkja n )zo ;6xx/2ividual reactions.

  Which of the following describes the role of inhy94 8+e5arhwy 2.+ z c7byt x)cfhudlgibitors in enzyme-catalysed reacgyl w fx7+)utah.h2 dery5z8c+bc 94 ytions?

  Which of the following correctly describes photosynth-dicwq; o9q;z 2wysy bzf9,w 5esis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps andt+ 9i4h9gnzbv mo j:h2o;aq)i multiplm29h;9jihaoqz)o bn: 4t gv+ ie enzymes.

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

  Which of the following best describeswfi:1fiqf-m0,zf qw 9 the inhibitor in the image below?

  Which of the following statements are true regarh z/pygt2 s7 ;0v3ouweding regulation by end-product intow; 3v02ph g/7zesyu hibition?
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 da ;3w(v tbh-yuarkened structure in black is the substrate and is bound atwa-ytb( hu3 v; the active site.

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

The equipment below can be used to study the effec+13n +pee bbkct of temperature on the activity o++p3eenb1b ck f the enzyme 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 enzymes interact with s( y72;c teqxuko+umb 3ubstrates to catalyze react 7u+x(q cmbukty3o2e ;ions?
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 reactv l fd;2ptv9/.3 pnxkdlim ;+pions can be measured.

  How does denaturatiolafp0smj*ztqzs0 a 4 q5 iy(15n change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which s gy)xnk.1),ijb u0c2akw n8d of the following statements are)bxgwysd,ua )k1i0 j2ncn 8.k 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 mammalscni3(lb 0s8db oo+udj6i4o -n or endotherms from ectotherms that have fluctuating body te6slono uci-n b(48ddo0 ij 3b+mperatures?

  A metabolic pathway that converts threonine to the end-produjn9vq 4l7cl :x c7i3juct isoleucine consists of five reactions. Threonine is converted to 3u:4xc7in79v ljlcqjvarious 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 of an enzymatic j0a+ o ar:m:il:zh;2 c,w.p crz jv6ubreaction. What is occurring durij.hlc :pw,;zoz2b vjur0:i r:m +a6 acng the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzymatam/xe o2:p -h-ojhm/bqd5-vup 9 z zm;ic rp9mzm--o5qbhzuo; x/ h2v/pe :m- dj aeaction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that convertmto 1ox3s0;me s threonine to isoleucine.



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

  Enzyme A (Enz A) was ig*pzvz.8 r-)ovv4krf mmobilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relativovpk*zzv8 .r )4vf-g re 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 folltoth+ 7 diu8n:0 -xovyfsa*q)) 4mcu rowing is the best way to keep muoysuqtd4: xoh +7 ic n8a*ft-v)r0)enzymes active for a longer period of time?

  Which of the following describes sk4kr ur;1xgu/ome types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release pes6 a ky1v8vr;mptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant tky a6s;v 1vm8remperature 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 reactij3vb;o 6k+sm xon 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 reackb osx36jm+ v;tions. 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 intd/:am 3wxsc l)o small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize thw l cx/)amds:3e 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 sod nq mr/*-iu,hown below. Inhibitors to the enzyme HMG- CoA reductase can loir/od-m,nq* u wer 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 70u1 szc5 pquddq;wlb f /8afk3p2 /ugare 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 ano zq7 /wy(fzj 9+yxi9lxu /i0rd were given an experiment which demonstrated the effect of temperatr 7z/(wlo9 j/i0uz9y+yfx xi qure 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 tebbuaqvje a xtyijjr-77pk)8;4h +i/ )mperature on the efficiency of lactase activity is tested. Which is an appropria7b) hjrbtpuqjy; a-7ivaxik8 j )e /4+te dependent variable for this experiment?

  A study has been conducted on the activity of a specik4c( 99lcfuhn lpw.5sfic lactase (Bg10), analysing the effect of pH, temperature and glucose concentrhku (9npf5ls4. cc9w lation, 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 drunak;z 8-wn ga3wp( :s4ry+ ygngs for treating patients with malariwpk-:yn3a s( zr4nn8;y w+gaga. Describe how anti-malarial 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 increasinezd is;z y.:4dtzspp a11ix-;g the concentration of an enzyme affects the rate of reactios4xyd .-zit:zea;dpiz;p s 11n.
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. Wp kq0h2,mmm til8 c7 o:u;lv6shich type(s) of metabolic reactions are condensation relu ;:mlqs0 78 c,hptvimo 62mkactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme/fiebmx2y 04 p catalyzed reactions can be measured.0 xb/i 42mepfy
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 chemica-i t-a-lm+ ilal reactions, giventl+a-ili --am one 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.