Which of the following macromolecules descrina9f ,m kz00org5:n w:am, xhsbe a typical enzyme?

  What type of reaction is photosynth1-)cm 0s bkk ,5pcdspzesis?

  What is the substrate for the enzyme lactase?8b kr:my(f8 db

  Which of the followin/./xh x2evjlml *ti13yelr 5fg stages of cellular respiration takes place in the cytoplasm*y5lf et31 x lh2/rx.lei/jmv ?

  Which of the following would not be useful in determining the rate 8r/ v*ywnlj3c/xrz r9pqvm n)(i3fd sch32u/ of an enzyme-catalyzems82cvhwp/z(y r/* x3 9)u 3 3flvqjrdcnnri/d reaction?

  Which of the following processes may bktg9cdx(jl g5e5 s; s-e described as catabolism?

  Which of the following (csq.g d w89kfstatements is best depicted by the figure below?

  Which statement aboujl (1 e0+fxakyc d *vzs9yld);t enzymes is not true?

  Which of the following graphs besta1 7 umofroyck:6p 1o1 illustrates the relationship between temperature and the activity of enzymes o 1mf1uky7o :pa6oc1r such as lipase?

1.Sketch a graph to she drbfg:9v nut+6 dc;jr,l,x /ow how increasing concentrations of substrate affect enzyme /rj r+ gcdbf9tx,v6l ;,u: ednactivity.
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 t7p;zxfo; 7 :+a1y85et9ljcsk rtki/x fnyb - diagram outlining the Calvin cycle is shown below. x/f;i 8ttzakxet bl+ y519pk7jsnry; co 7:f-

The image below shows the catalytic site cuo owh;g(7ppn ,sp2 e5z+u vof:7x5qof an enzyme. The substrate is shown in black and is bound to the activzpu:;vfx7o52u qpchn g+5 o o(p,s w7ee 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 desc7ci 8z pr2j p-km;ov6qriptions of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reacqij v2zc p8o -pm;67krtions.

  Which of the following describes the role of inhibitors in enzyme-catalysedu- /, udq,jecqs7uv4l reactionse, q-js 4u,u vl/7cqud?

  Which of the following corrc+ ;8vz vtvg*23pv9wbmbks8-espl + eectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and m6/4l nauvt ,xmultiple enzymes x,a/t u4lvmn6.

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

  Which of the following bes8;xjvrqugzfqmg vkf n:+ obj 0 )l4(0.t describes the inhibitor in the image below?

  Which of the following statements are true re;0jlo rnbw)) jgarding regulation by end-product inhibiti);nob)0 wljjron?
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 enzyncf,flm sh x):h0o0g*me. The darkened structure in black is the su*hxl ms0cfhn,0ofg ):bstrate 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 6lvk wt17()crbwyp,a of temperature on the activity of the enzyme amvw6 c1r( tb)7,w ykalpylase.



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+q f.3guusb/pe; nr;z how enzymes interact with substrates to catalyz+ eu;z; .buprg3 fqn/se 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 catah lqwj inp t43ez+;9ufo6v*p/ lysed reactions can be measured.

  How does denaturation change the properties ofo .4ez 3-ca:lb tjpq1)wqc ai, an enzyme?

  Enzymes play a role in catalysing reactions. Whichb20kll kls 3h2pc+/q u3o c*wh of the following statements are truec/hlw 03hp*ul c lkb s232+qko?
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 endotherms frb5t/mwk- vu -uig:ju3om ectotherms that have fluctuatgu u3- /:ijmv-utwkb 5ing body temperatures?

  A metabolic pathway that cy q8x2kpb btvxs0 7s0*h 1acn6onverts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is convet7 hbkxy1cv qx 8nps2 0ba6*0srted 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 s yry*zs1 7o:yx*8rkz of an enzymatic reaction. What * s7rzzx k8y1oys: *ryis occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentr6h c4h ypt:8bration on an enzymatic reaction. What could be p8 yrhcb6th:4 the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threol a2e6uw-j0(+xy awuxnine to isoleucine.



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

  Enzyme A (Enz A) was imm37 l1luy l5zcgobilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity llz 357guy1cl (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 denatureequve 3 t d,j/ 0ex(fs/kau3w6d. Which of the following is the best way to keep enzyks/0qe xd (f63/uujte3va e,w mes active for a longer period of time?

  Which of the following describes some types of e5 v o.2u;pwmccxtracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A nxk2prvqw9 q:ii/x4 8 pyh/fryr*pi3l7/3h t study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperature ofw 34qlxpxipry*i:/tnq9 v 3h7rhk fy/ i8/rp2 $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 vc.za6 h2fn0p , 5fa s,urb5.qy0r )8jplmiqusubstrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activi,b aml) u6f0zrn qq8p0.ajpcyv55rh.,u2 isf ty was monitored for each of the 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 turnip root into small cx/wjn+(qnk jj/q) fz 3ubes. 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 storek/nf qj3w )nqx/+z(jjd 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. Inhi)qfd ,(w1jdr ibitors to the enzyme HMG- CoA reductase can lower the production of cholesterolr1,d)fwqj(id .


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 followin8. fczoi.h 3kjg are 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 5j mjibrl6eg3jn ngp.0d5)p( classroom and were given an experiment which demonstrated the effed)(.gb5mj 5lj eng6i0j pr3npct 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 temperature on the efficiency ofr2 g/s dmsu6q4 lactase activity is tested. Which is an appropriate dependent4q d2ms /su6rg variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bl b-+xxw,; vxug10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produ+x,uvx; lxw -bce 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 patients with malari7s1t ojp0m; ascvnf:/ a. Describe how anti-malarial drugs are beftsv mo aj0:7n;pcs1/ing 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 co2--vf4 c tzy3e8gyoponcentration of an enzyme affects the rate of reaction. 3yvzc2 to --fgpyo48e
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 thmjeuv /4 n;a x( oqv4v;a;n/co9pi5g mrough metabolic reactions. Which type(s) of metabolic reactions arn4m/4 gv /9u;omqc;vjo aav(ix5pen ;e condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways ce,s;t4bg nk/ ;u8utqthe rate of enzyme catalyzed reactions can be measuru84gqcke/us bn,;t t; ed.
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 contra -resn:bw 7m1wst intracellular and extracellular chemical reactions, given one example of each type-wwbs1n :m7re 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.