Which of the following magzi y9 6k3l7m nq;nks5cromolecules describe a typical enzyme?

  What type of reaction is photosynthesis?59xujdxc.y, k

  What is the substrate for the enzymv,-5z:ebf: zcgd 6zh *0zfnvsx/p o ;se lactase?

  Which of the following 9+oc689alfjoe d pz )lstages of cellular respiration takes place in the cytoplasm? ) 9lcdjp6 z+8oalofe9

  Which of the following would not be useful in determining the rate of an enzyme-.dg2-vj d amr5cd2mj -da5grv .atalyzed reaction?

  Which of the following processes may be desxu a*t9(wl3ybd0m/:;ulw cm(p7x cc zr:1y dlcribed as catabolism?

  Which of the following statements is best depicted-mcahfem7f 2+nxca*: k h o;l(5crx7v by the figure below?

  Which statement about enzymes is notu: kfpt8alsnns/t.c -6 (w4-l eq5pz c true?

  Which of the following graphs best illustrates the relations(ph 8we5g,i; * 6ysiyvj gwbg g79ag1ghip between temperature and the acty 9*5p, ge8hsa7 bggjwgwyi1g i(v ;g6ivity of enzymes such as lipase?

1.Sketch a graph to show how increasing-2b5ta -op mj95uga fd concentrations of substrate affect enzyme ua -t5ag5b9mfo-d2 pjactivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of mwx/v.cj *,1f)g1 pco;jkj jv enzyme catalysed reactions. A diagram outlining the Calvin cycle is shown below.c/f)1 oxjkvpj .j1cm; *,w jvg

The image below shows the cataly3 tkz.i 8*dtg- hk.ga;t6ifnhtic site of an enzyme. The substrate is shown in black and is bound to thed 3nifz 6ttthgag-i.8.;k *kh 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 metabolic pathways q,5qx 3rtsl43t 9ehjm shown below? Letters 3e9qstj5ql43 t rh xm,represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed rplx;d3p.d 0f eeactions?. 03xpfle;d dp

  Which of the following correctly desc xj9r. jnbt13iribes photosynthesis or respiration?

Many enzymatic reactions happen as pathways invo yx3ifs.4mzr5 *sq-vw) rij7olving multiple steps and multiple enzymqr y3 fs45imws*rvo)j- zi7.xes.

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

  Which of the following best describes the-5yfaeht 7t .2kf,n11g umvpf inhibitor in the image below?

  Which of the following statements are true regarding regulatm.) 0+ums5cj ne a3qrw1im/*s7l8mqx zvn0 la ion by end-product inhibition?)wne jlx.q7 m 8*mnm1ci/vr u+mas3a5 s00lz q
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 showg td8u*ua (f12nea- ees the structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at1-*2d ue(tagea un8e f 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 tx51k64h qq ryeemperature on the activity of the enzyme amylase5q4y 61qrxh ke.



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 d w :hx5ux*7w g ol1(r4pt.qou fw.:wzqescribes how enzymes interact with substrates to catalyze reacq(loq: rxz4f5g1wpxu.h w.t7 wow: * utions?
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 catal;0c2 cploj2i3c d9 d8u2xdp3 jbppt 6fysed reactions can be measured.

  How does denaturatiojz kcov p40s*plcw: pmq1e9ft 1j/ 03cn change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statements -c;8wy9 cvvjrare true? jycv8w;-9v cr
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 frojt1 viwx9+r/4w2; osl /pcw lom ectotherms that have fluctuating body texs9ro+i/cwo / v j 2l4t1lww;pmperatures?

  A metabolic pathway that converts threonine to the end-product isoleucin1i,cg s- npig*e 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 in the pathway. i ,inp1 g-c*sg
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 increasiv8hs, 8peku p0at20 q9m8 lfmtng pH on the rate of an enzymatic reaction. What is occleap2 uspm8kvt89q0fm h8,t0 urring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate con(b hb+0ua5)r4w nycq pcentration on an enzymatic reaction. What )w+bbhp (cyrq54 0u nacould be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to /bfmsb;bh 3: hzm(g(9, uhqyu 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 and its ac9fz 0di;ab;oeap ew :+tivity was compared with that of a aai ;p d:0;9be +eozwffree enzyme in solution. The graph shows the relative 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 o 25-zeu:vmusl/h(n a8ip8dx zf the following is the best way to keep enzymes active for a longer period of time?sun8 ma58z l:id(p -/2uxzhve

  Which of the following describes some types of extracellular enzy*d8kq +y 2ol op5kako0mes?

  The enzyme pepsin hydrolyses proteins to re k b zjpxn4g:kef56d9(lease peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity5(9d:z fg exnjp64bkk 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 enzyme with increasing suknm5nr w5w 6chd61(elbstrate 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 activitym6rw hwd65k 5n1lc(ne 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 spw- d5kyxo: 8t 84zjmrtudent cut a turnip root into small cubes.8j-o pzt m8d wyxr45:k 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 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. Inhibp*5vs6w3zmf h:n8 jexitors to the enzyme HMG- CoA reductase can lower the production of cholesnef 6h vp5x3:wjs *mz8terol.


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 invocoj83aw (9oh ;blk 3ko* w(cjylved 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 rea0-, ucq yqtw 4ydfn/8vctions in the classroom and were given an experimutyq0n y-w4d q/8fcv,ent which demonstrated the 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 in-6 oncab8 eahe0y-,xvd( z:rtcreasing temperature on the efficiency of lactase activity is tested. Whb ot0a-8:dyv x,h r(a-z ece6nich is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), tjm4w) a-kj0e analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactw0km 4eajjt )-ose-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 j wm*o iwa* p,utn;(:jneed to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being disjj*w : i*,wauont(m ;pcovered 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 concentratm;i( qfkfu0u8nqb e2 p a.6)eoion of an enzyme affects the rate of reaction. nim( .e q;)bqpoak0ueuf 268f
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 t3;ghmo 0 i d7pakq3z5ehrough metabolic reactions. Which type(s) of metabolic reactions areg3m odz3;0i5hq pk 7ae condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed re14 ra6+mrvb9ep xa es9actions can be measuredrrb46+9 91 psx eaevam.
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 chemical,irayd. p6;ts reactions, given one example of each type of reactiony6t;,spd . ria.
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.