Which of the following macromolecules dq g*3uen 3qqa6escribe a typical enzyme?

  What type of reaction is photokuqz6 /6a1o cesynthesis?

  What is the substrate for the enzym1m8-zcphny bg6v55wge lactase?

  Which of the following stages of cellular resic tuhv at9i27s3dz*-1vt*tapiration takes place in the cytoplasm? 3iuchtza7* 2- tva1d*tts i9 v

  Which of the following would not be useful in determiilh x.pys32gz+a,8ak ning the rate of an enzyme-cataly ,8p yx.l3+aizhsa gk2zed reaction?

  Which of the following processes may berle-usiwdmq(( n(,pf fx o). m)1fq6x described as catabolism?

  Which of the following statements is best dep6i.3dgvw5kc p;u7gs-de9 y u +3 zfwedicted by the figure below?

  Which statement abouio nqb tvto0 aq6q,/8lu5xw)5 t enzymes is not true?

  Which of the following graphs best illustrates the-5wh;c( tt pd w 1yvcvil-95hq relationship between temperature and the activity of enzymes hchptw(-lw tvyc5q15-di9;v such as lipase?

1.Sketch a graph to show h6v f a407vdjsuv9oljq11z bhh)a ws+3ow increasing concentrations of substrate affect enzyme activit3u4jd sas0v o1h j1vwhv qabz 97fl6)+y.
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 outlinih0ico9n75zj l ng the Calvin cycle is shown bn 9hz7l0 o5cijelow.

The image below shows the catalytic site of anki zzk b9ls084 enzyme. The substrate is shown in black and is bound to the 9k4 zb8k0ls izactive 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 des8t2gus8r:hmw d g7/zl7jhm* vcriptions of the enzyme catalysed metabolic pathways shown below? Letters represent var8zhg8us/dm7th2 mwl : 7* rgjvious products of individual reactions.

  Which of the following describes the role of inhibitors in enzk l,kafv3x 9p8yme-catalysed reactio3vx plk 98fk,ans?

  Which of the following correctly describes photosynthesis or reapt lv ;wa--9wv8d+ fhspiration?

Many enzymatic reactions happen as pathways involving multiple xk7rom:g9b g:09jxyn steps and multiplejmn:09gbyo g7r k9:xx enzymes.

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

  Which of the following best describes the i*o 9kn9az cjo1/0hs fikh3v(oo4h cv2 nhibitor in the image below?

  Which of the following statements are true regarding re97urj7otzk.;.sd rw agulation by end-product inhi du;9sw.jr77artz .ko bition?
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 darkenzq9yx(*s 2uzss 3ayj. g mj-q0ed structure inszyaqz230 . -ug*9sq s(yxjj m 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 tou)09) hnjjgqu07:u c k0azsyg study the effect of temperature on the activity of the enzyme amylaug0kuy:j 7 0hq0ugnjs9) z )acse.



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 sta9w .hjg ycqf1fcwsn t.),08qh tements describes how enzymes interact with substrates to c f.j0wqsthw 89gh ,)yq cfc.n1atalyze 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 catalyf6p:hw; gb+w esed reactions can be measured.

  How does denaturation change the properties of and5g-m ov.n/a e enzyme?

  Enzymes play a role in cat)vrdo-o+fup 4alysing reactions. Which of the following statements are t-+4pordu o )vfrue?
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 thra2cnpnlj.676s :/ l3k zqag eat separates mammals or endotherms from ectotherms that have fluctuating body a6acknq3r 6zg: s7./nje 2 lpltemperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine conj-1oyp, 8razhsists oaj1zr ,-o p8hyf five reactions. Threonine is converted to various 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 on1m-0 h ej.at0lz )ayd+tq-kol the rate of an enzymatic reaction. What is occurring during the 0ta 1a +ql 0khzjd ytm-e.-)lophase labelled section X in the graph?

  An experiment tests the effect of chatord 6i1 g,q2z gqcs)5nging substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this expe6d or2z1c, qis)5tgqgriment?

  The diagram shows the pathway that converts threonine to lxh0qi wyc2no.7*/ m pisoleucine.



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

  Enzyme A (Enz A) was immobilized on a matrix an(6qwn+*-u acmvwvkj.d its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme aw+wa( nk-*cu.vj6vm q ctivity (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 wa :d7z0 e k+suwems:p0my to keep enzymes active fodswk:mp+m u70 z :0seer a longer period of time?

  Which of the following describes some types of ae38e/m 4 elpq wn8n9eextracellular enzymes?

  The enzyme pepsin hydrolyses proteins to relea1 wk1+d x9tz;buzl1 ihse peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on eb1i +9xw;zkth zl1 ud1nzyme 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 reaction of an idf 5hjtgdn 579+r n:henzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the5 g:hifdn9 dj7t+ nh5r reaction, and the activity 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 turnip0gytlmu o f*+gh3.fq; root into small cubes. They m*u;+gy0fm qgf.3 lot heasured 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 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- -2+kezrhhf*fCoA reductase can lower the production of cholesterol.f *fkz+rh2-eh


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 invht(qs7w; f/wy4jt cr1 olved 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 reac:7mq ieqdu(tcm4td* )tions in the classroom and were given an experiment which demonstrated theqqt*u) 4 ei7 d(dmmtc: 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 temperature on the efficib:)rkgu9j,p5r5c /qnod*vnr ency of lactase activity is tested. Which is an appropriate dependent j) c ubor59d,vr/kp*q ngr: n5variable for this experiment?

  A study has been conducs - c-mpvt.8h o:v,a-mybvxp+ted on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactv.xvpm-8 m ,-vs-+c ytp:aohbose-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 mal hh o*eu7;.tfeisew1j t*x84oaria. Describe how anti-malarial drugs are beinge8hwh7x u41;tjio eef *.t*os 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 concentration of an enzyme affect* z 8tnw2tb(lss the rate of reacti *tnw2l(8bs tzon.
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 rnc,5* hf8xicl x,4wj ieactions. Which type(s) *nljw,if c8hix,c45 xof metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differentxg0 a kum+5vkap)f7f5 ways the rate of enzyme catalyzed reactions can be measured. m)up 50agxffakk+ 5 7v
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 contraa 1ppocvj mt8f;4 c;+zst intracellular and extracellular chemical reactions, given ocjzcvm8ppf1; 4+;at 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.