Which of the following macromolecules describ-5puw.lt j .yje a typical enzyme?

  What type of reaction is photosynths c8,8kcakq-bv-c fx 4esis?

  What is the substrate for the enzym2ow)ii2ed6 i5d)i nq pe lactase?

  Which of the following stages of cellular respiration takes place 95ei1: dur7gd. fqobl in the cytoplasm? 9 fib1:5eud7r gld o.q

  Which of the following would not be useful in determining the rate of an enzykog7uqxlps-r o q t:/5p(e1 h6me-catalyzed rearp tl-:e poq gxu1oq7h65(sk/ction?

  Which of the following processes may be described vc03 k+qnqh-7q61 lpneonhc* g;zk.m as catabolism?

  Which of the following statements is best depicted by s ;qxt :0q6d+:g zukyqthe figure below?

  Which statement about ene*0:0ka w7u1eg cstthzymes is not true?

  Which of the following graphs best illustrates the relgbwy(,/v(n jtsu-*b- smol h9 ationship between temperature and the activity of enzymhs,(vtb*u/w lo-b(mgsj 9 y- nes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect enzymd7 )z n.2wejo*. pyi1wbyu zt7e activ1.7dw u )pw*z2jy.ynt zoi7ebity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzymn6s-jc9(0 d por h4vjaz*k(ga e catalysed reactions. A diagram outlining the Calvin cycle is shown0j pjk6s*4gnch v ( o(9r-zaad below.

The image below shows the catalytic site of7ys) ;orm kabv/v ;+tw an enzyme. The substrate is shown in k;mr)y7 vbo /+sat vw;black and is 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 metabolic pathwaysr ajr +50*lctr shown below? Letters represent varija* +r l5t0crrous products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catal6sp(lvz,k5:o2xghi 3 bjezg 8 ysed reactions?ej 52: 6zhxlbpks vi, ggzo3(8

  Which of the following correctly describes photosynthesis or respirtd2:: ncffasgi 5:fp q+0b0elation?

Many enzymatic reactioy6r iin+x) 8zqns happen as pathways involving multiple steps and multiple ei6r8z) yqx+ninzymes.

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

  Which of the following best descri :st8 f42 (ep razfozeh2gi8i8bes the inhibitor in the image below?

  Which of the following stogl 976u*hrjw atements are true regarding regulation by end-product inhiu 67hgjrowl* 9bition?
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 da8ob xq68o,s2.t lub akrkened structure in black is t8uob.6b ql82, sxa kothe 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 effe a6n a:,fl;jbtct of temperature on the activity of the en :n;6a bljfat,zyme 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 sg. kdx*fmg(jc5py+ny xy.j /4tatements describes how enzymes interact with substrates to catalyze reactions?m jn4c pxg+kyf./d*xy 5j.yg(
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 reactigw . -y dbd0zi6ly-ug1ons can be measured.

  How does denaturation change the properx-pl t2k)f -tuties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of7k7;vpiovm6q lhs57 l the following statements are trvml7;lks56vhpq7 io 7ue?
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 cyy/6,q/ 0-5ef:v ib cegrmra p:*w itthat separates mammals or endotherms from ectotherms that have fluctuating body temperatur,5i yq6vb: g*ic//ae: fptwrmr c0-eyes?

  A metabolic pathway that converts threonine to the ennfl0 coaowr- u;6v-k;d-product isoleucine 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 pathw0nwkr6lc oo v--au;f;ay.
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 no9 dul13+ a q1owyki,the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the graphiyal1kn3du+ w9 o,o1q?

  An experiment tests the effect of changing substrate concentrati9t2y h vmgo)3con on an enzymatic reaction. What could be the independent and dependent variableso hy v9c)23gtm in this experiment?

  The diagram shows the pathway that converts threonine to isoleucine,9j)h wdn* q1dvu/-ax7 voken.



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

  Enzyme A (Enz A) was immobilized on a mat1,qw 4f ,nkg+wqzr-qnrix and its activity was compared with that of a free enzyme in solution. The graph shows the w,n rkg4w,qf-+q nz 1qrelative 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 following is the best wayrw3(0jc;r ixjzwr z,b0yt 6t, to keep e rzrw(tz, bt0i3x jj0y,wcr;6nzymes active for a longer period of time?

  Which of the following describes some types of extracell+ ,0ibibjb ez7ular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A p16nixty fo s8 (2it:jstudy was carried out to determine the effect of increasing substrate concentxjipn2:f soiy81t6( t ration 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 an enzyme with i*p c0ve 3(k a)i+jaxiincreasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, vpa3 ce+(jiik0 *x)iaand 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 ss* *cm .18 a5fmvt(vy uas,xhw3n(xtr tudent cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The homogenate m8h1 (s,au ct*5.ytrs mw( 3a*vxfvn xwas 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- CoA rynatbka9/hu z4,n hui29no32- 1 jzateductase can lower the production of chole1a-koz 9u93n,taa h yb hunzt/ j2i24nsterol.


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 involved in denaturation? q-p3sivx2w. + cexs..7ag gjnuk03iw
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 and /v/;lr r bn1oywere given an experiment which demonstrated the effect of temperature ooryrv; 1bl//n n 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 tem w g6n63d3h:m5 xyrehuperature on the efficiency of lactase ac:wd5 ne ymu3xh 36rhg6tivity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted c6ijj :xfx8w fk7ne9* 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 f *c 6nwjikfe8x7: 9xjto 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 patomo jo3 c898weients with malari8oweco8mj39 o a. 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 increasing the concentra *.rgeeihfa -0tion of an enzyme affects the rate of reaction. ife. a0-h*egr
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+7oc- kyix,wr metabolic reactions. Which type(s) of metabolic xor icwyk,-7+ reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be me/ 86gh1eqwy iaasured. ayqg1 he/8 6wi
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 prh8;-bal; u4xmpzv6intracellular and extracellular chemical reactions, given one example of each t;-6rhmx p 48z pb;ualvype 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.