Which of the following macromolecules,ht 8s-bb p+np describe a typical enzyme?

  What type of reaction is photosynthe8a:o pkuw )ig 7)zm)qdsis?

  What is the substrate for the ey8 fx.2xtr ft8nzyme lactase?

  Which of the followizi xczz6r-4j1h v-djrqm / +1jng stages of cellular respiration takes place in the cytoplasm4jxqzd h/-zj-6z1i 1 rc+mjvr?

  Which of the following would not be useful in determininat .18jh o2msig the rate of an enzyme-catalm8s2. 1atih ojyzed reaction?

  Which of the following processes may be described as cm/gw8j ngd0 oz,qqs. ;atabolism?

  Which of the following statements is best depicted by the figur 0i +cwv(t5dkv,0mtwp4wv 3 n03brnole below?

  Which statement about lt lhh5.1xh:b*b t p xst-uf8ru3 93ujenzymes is not true?

  Which of the following gr2hkefo v/,-j9lw, uqsw j7l*(vw+ngyaphs best illustrates the relationship between temperature and the activity of enzymes +vwqglu/7wn-hl wfk *v9j ( ,ejs2,oysuch as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect enzym .g6:u4.o)jm2.xb1yj phm9 c owj mhjee acb1p) 4.joh ug jje9 o 2mmy6.:xchjwm.tivity.
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.wp 726bv emo2y A diagram outlining the Calvin cycle is yeb m2o7vp 26wshown below.

The image below shows the jbtz-2;tlwia6+ z8xdh.( ye scatalytic site of an enzyme. The substrate is shown in black and is y(i8d 6jw 2+lx. t z;hb-tzaesbound 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 ;hz2uq8 vnzo9;a1mk othe enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reazzunh;2amk o1 q9 8vo;ctions.

  Which of the following describes the role of inhibitors in enzyme-catalysed reac+ cf6yo 6sb(r f;y4t8w/gqu hmtiyqwfbm ( fty/u6c84s6+rh;og ons?

  Which of the following correctly describes photosynthesis or respicbr9q q1foq j6/;sbje5x r*, zration?

Many enzymatic reactions happen as pathways involving multiple steps and multipl0 wto(:tszttcmw* ( pr .4f2xge enzymf t2m0 cp:(t ztwso.xw(t4*rges.

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

  Which of the following best describencqg f5: mb. 1-vxbi*is the inhibitor in the image below?

  Which of the followip5dyk;h h )w/jng statements are true regarding regulation by end-product inhh 5j;)kp/wydhibition?
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 structu+0fliivxl vt m8sh8+ 4re of the lysozyme enzyme. The darkened structure in blv t8vxm8ishfi+ +0 ll4ack 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 tempet,p w u- t*f;xjy0d9(jc1i zkvrature on the activity of the enzymjt k0v9-;cpitf1(yzd, w uj* xe 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 statementk) j(;m:gx xetio s1p9s describes how enzymes interact with substrates to catalyze reactkoe1s )9mj;( x:xitg pions?
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 reactions can be measured.n-51nz)r imd v

  How does denaturation change qmo0u(x9plel 5-elk )the properties of an enzyme?

  Enzymes play a role in catalysing (50r db m;z 8*r6pqn sv4w1pxy5 tnsxvreactions. Which of the following statements are sn *0 s(tqxpzd;np16r5mvxyv85w4 brtrue?
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 th4*crz 5qra 6wmat separates mammals or endotherms from ectotherms that have fluctuati4a6wz mqrr *c5ng body temperatures?

  A metabolic pathway that converts threonine t ifb clug;u51 wpm)f99o the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by differl);fwuf 5 9gcbp9iu 1ment 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 increvj)+v-t k jc6nasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in t tjnv+v)jk-6che graph?

  An experiment tests the ec+xm +ar )m0cuffect of changing substrate concentration on an enzymatic reaction. Wh0mxr amcuc)++ at could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that c n i6eizif*l d0)7+j +z.-n- qvprrdabz 5rm0ronverts 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 a matrix tcmdpm5+-b41:v esqr 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)+1em :dc5m4qvsb rpt-.



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 tqo -:,f: yoqzfhe following is the best way to keep enzymes active for a longer period of tioz: f,f- yqoq:me?

  Which of the following describes some types of extracellular enzymmimt774 cv jlk64+rik;3d,tl;r m t hpes?

  The enzyme pepsin hydrolyses proteins to rer+ rejgfi7 4wcc7 z4s(lease peptides in the stomach. A study was carried out to determine the effect of increasing substrate 4c7 (js+7igcwzfr r4econcentration 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 reaction of x;tpj1rtw4bp8.g s2 q 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 reactions. The curve marked A coincides with the actixtpp4 ;.g1 jqsw2tb8r vity 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 turnips0pmc,df9 2fmj* +-w 5oacgwb root into small cubes. They measured approximately 5 g in a weighing dish, addw5mg ,2a-c+dfmbcf9*0o ps jwed 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 HM+e1eacv sf d(.bam9s s 5k)i)yG- CoA reductase can lower the prod aym s)c5b ifsa+ vekd).(9s1euction 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 ke tzquus2s. *m 2z9u*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 classrol4n5kn b(5pzd0jr;/3 xnqu xoom and were given an experiment which demonstrated the effect of temperad 4ol5j /px 0z un5r(b3qknx;nture 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 (38iayd+ lcmptemperature on the efficiency of lactase activity is tested. Which is an appropriate dependeni+ alyp3( dm8ct variable for this experiment?

  A study has been conducted on the activity of a specific et;2/)m/ w nele(qimv lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may m /emn(e)it /2we ;lqvpotentially 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 patientrcd u+jv3honla/g ll8z.s :*6s with malaria. Describe how anti-malarial drugs are rzjn8a3h sg c6u .lo/vl+d: l*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 increasivksa:yz 8x p/2ng the concentration of an enzyme affects the rate of reacty8pvax /k2 z:sion.
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 s4t2b0ae /wy v f(5 kw-avqo.hiynthesized through metabolic reactions. Which type(s) of metabolic reactiyb45a/.(-20 v fv at hqwwioekons are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzevi;98tlgr zx *d reactions can be measurgvr ;8*zx9 itled.
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 contrasz s8bq5:.hfokyz 6,k mt intracellular and extracellular chemical reactions, given one example of,:6zm8 qsokfzb.k5 h y 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.