Which of the followinse lvk,dz(/ 6zg macromolecules describe a typical enzyme?

  What type of reaction is photjbcred/5qq8 qw+.bg 6 osynthesis?

  What is the substrate for the enzyme lactase;lt ms m2,lkv 6nmtw*-?

  Which of the following stages of cellular respiration takes place in , 8c6rhfprx 0.nljn(jcryb.j0 qg+j /the cytopla 0b6rg c.rc+nh j0rjfxnl ,8.jjq/(py sm?

  Which of the following would not be useful in determininpl 8b8mx /zec9g the rate of an enzyme-catalyzed reaction?8p/ lcme 9bz8x

  Which of the following processes may be described as ca*u- un8h3.juu0ugjigi nd kg:*; nz/*hxr1 cgtabolism?

  Which of the following statements is best depicted by escad3in t(v -+6*ry ithe figure below?

  Which statement about enzymes is not true?oj*vc7hf5;o; wa5o tz

  Which of the following graphs best illustrates the relationship betwywz/ tpvl64 z(een temperature and the a/z 6tlwy4( zvpctivity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentratr tb +zcwp+//kions of substrate affect enzymeprtc+/kwb/ z+ activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enb:ld3r yv i/ 6vs38:fr, ihiorzyme catalysed reactions. A diagram outlining the Calvin cycleiyirf68r r3i3 o/sd h:v:v l,b is shown below.

The image below shows the catalytic site of an enzyme. Theo-qg v4 qeh5heaw, 58w substrate is shown in black and is bound to the 8wqe45ho vahw5eg -q,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 sh pdia-qc y3:l40oz md+own below? Letters represent various products of individpa3+m4c l0 qd yz-io:dual reactions.

  Which of the following describes the role of il yd9w,k/ 2p5, uyuci7kel8s/pb2 pexnhibitors in enzyme-catalysed reactione7py5kyp8ku2b,wu2,//e p9cx ds l ils?

  Which of the following correctljacdld 5/ r a-r/i1;cky describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving mu3x ca n*y;e4caltiple steps and multiple enzymc*yc a4 ;3xenaes.

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

  Which of the following best describes the inhibitor in the image below58inqbe fe p4q);)epx ?

  Which of the following statements are true regarding regulation by end-prpyq+9h/ ddl6,xkjl/ noduct inhibitio k dxp6qd/h+ l9,jn/lyn?
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 darkene9 k (cquq4j2mld structure in black is the substrate and is bo2 (qkumc9q4l jund at the active site.

Which of the following characterizes the active site of an enzyme?

The equipment below can be used to study ttx3,j,xp eynw fme..2he effect of temperature on the activity of the enzyt,f,.npey jm2 wex .x3me 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 statements describes how enzymes interactv*b x/l)xkn6g+j dv+ ko yk4z6 with substrates jo*k+ n/+zv6 6bgx)kl xk4dyv to catalyze 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 catalysed reactions cano 7r5. nt48 htiuqpobmk7 ghxx5s-1q5 be measured.

  How does denaturation change the properties of anpt* 0*gj9dmr0-doj) n ,regcr enzyme?

  Enzymes play a role in catal z02u9 8zmi ijujuoa,5ysing reactions. Which of the following statements are ,z u5z 0mi u2ai8ju9jotrue?
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 from ecto/w5r.wa) afzjm jgl)8therms that have flw./w)zj58 g jaal) mfructuating body temperatures?

  A metabolic pathway that converts threonine to the endm 29wwb pspg;eu(2.v:iclfi;-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by 2i.i2sce uwmv : ppblgf9 ;;(wthe 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 ratea, qy u;94-y/xvb *obcl3gurj of an enzymatic reaction. What is occurring during the phase labelled section X in the graph?uv ;r-c3yo,gya bql9/ux *j b4

  An experiment tests the effect of changing substrate concfeknj+ ( z(s:zentration on an enzymatic reaction. What could be the independent and dependent varik:nze(+s ( zfjables in this experiment?

  The diagram shows the pathway that converts threonine tof:m;;(ebzp jx 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 anl2cg yc9w pk-rbvp1u4maa +;9d its activity was compared with that of a free enzyme in solution. The graph shows the relatabrkc 9py + 2lp-1 9mgc4;uawvive 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 pez 0- nx npqwp)n1++dway to keen dzn 0+pp+ e-q1pwnx)p enzymes active for a longer period of time?

  Which of the following describes somc ,i)q1l))sb+pmj9vli ng;y fe types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptidegw:r r9yr-e 0as in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity gea9r-0w r:ryat 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 incr25 dksp)p9r4suyuw v 1easing 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 activity of wup59s1s2 )dr p4kyuvthe enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cuta72q9)nc lsnaugy2-x 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 was filtered c)2xn9gn2ayla s7u -q 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 bel e a(7lkw(r+fn:zal3qow. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholesanl f:lzq73kwa (r+ e(terol.


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 followinggl3l8 ab/ caq,b8-bfvcwcq ql8x(z4;r a 84qu 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 metcjw n:l7yq 6ne*uln85-ucu 6 vabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic5vl n8:eu-juw ql6n7u yc6n*c 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 of lact gu vh19nlx57nase activity is tested. Which is an appropriate dependent varia75nu nlx9vgh1 ble for this experiment?

  A study has been condu/9oboo4idsv b4,o+gg p ta q95cted on the activity of a specific lactase (Bg10), analysing the effect ofb4o bod,9vqp 5o+ags9o4ig/t pH, temperature and glucose concentration, as it may potentially 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 fgmqvpez535eb y/ fo: 6or treating patients with malaria. Describe how anti-malarial drugs are being discovered with ne6f vqgye5 opb35zme/ :w 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 concentratiyh:vc7b 1l; :ivdy) kaon of an enzyme affects the rate of reactio kcaib7l;vhd):yv1 y:n.
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 dv 8pqs- 9ru7rc;fpn 0jown or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensats 97 up-q8rcf v;pr0njion reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of by7*rp e97vbe/ rtym6u (ncorrsz899 enzyme catalyzed reactions can be measured.v7ro re/e* 6b(yzm sbyn9pc997u t8rr
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 intracellupet(yznf-.04:;xr x +t lex dxlar and extracellular chemical reactions, given one e ex:nzd-lt(pexx+yf 0;x4t.rxample 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.