Which of the following macromolecules describe a tyf, py*ovka ;j:ltp.;apical enzyme?

  What type of reaction is phr .+kdipu4 db) ec6kq7 ;,hvyuotosynthesis?

  What is the substrate for the e lm*(u)b vhcc,nzyme lactase?

  Which of the following stages of cellular respiration takes place in the gm h)vb+k6lbng)d d0 0cytoplasm )k +g h6gmdb0b)l0vnd?

  Which of the following would not be useful in determining the rate oqw(*qadrvy;35/sbqtf;0wbs+3utldj r p 9h 7f an enzyme-catal q0ww; sytrs;+rd5(d9b* q pjb7ha/v3 q3uf ltyzed reaction?

  Which of the following processes may be described a,0z 9xp yb 5eedcqqgha)(z.e8.fz bd-s catabolism?

  Which of the following statements is best depj5svs+5ict -rxi+m ,j icted by the figure below?

  Which statement about enzymes is not true?mldf(2 w7.njf

  Which of the following graphs best il. t;rwhai bc*.g9ltwgqs 3g2wg 1:vy*lustrates the relationship between temperature and the activity of enzymes sucg cbqg*ww liw.v.trg ag2*sy1t39h:;h as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect e jd/f32cka jconup+sic: 2-2 knzyme anp-2c k/o +fk:ccjuda32ij2s ctivity.
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 ou v3 01eupug0qxtlining the Calvin cycle is qv p0geu 10u3xshown below.

The image below shows the catalytic site of an enzyme. The substrate nj-ejjj,axda3(qyu8 32 o+o. qs2s td is shown in black and is bound to the2.at 3 sox j ,2a(8nojjsydq 3u-+ejqd 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 v qx-d/;vaun+ metabolic pathways shown below? Letters rx d+ av-vn/u;qepresent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catakp;,w7tzhz.n ebc (v)lysed reactions?n. ( vkpe7thc,) bzwz;

  Which of the following correctly describ)5 wu-scvx t bwy+,*ia:a2cizes photosynthesis or respiration?

Many enzymatic reactions x,g g2fny)vg1 happen as pathways involving multiple steps and multiple enzymes.ggg v,)f1n2 xy

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

  Which of the following best describes the inhibitor in the ima4 yz5r nah370jk)pqu3da pv c;ge below?

  Which of the following statements are true regarad py/o i(3ei)ding regulation by end-product inhibitiod3o/yepi ) (ian?
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 cg2cf8vy d n8;darkened strucc8ny gfdc2;8 vture in 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 to study the effect of temperat)/q9 rrgz qpd1ure on the activity of the enzyme amylase. q9r1z)gdp q/ r



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 ervcw q2gx1 o /-qc*8yd6jh .zwnzymes interact with substrates to catalyze react- vwc g dz/oq*w1hr6q28x. cyjions?
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 catalutw: 6p ;siav yayu)/8ysed reactions can be measured.

  How does denaturation change the propert5 3q0yfn g.tkci he9jmdl8p11ies of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following rx /m)o r .cb0ck;e6ka8r gki8 sb6)histatements are r/)ia .mgr60 s8bx 8kb)krhcoeci;k6 true?
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 endothermshr5 j5s a mw*nw9 1ebvgadb4(7 from ectotherms that have fluctuatin4 5jsgd7w1eav hb nm9b *wa5(rg body temperatures?

  A metabolic pathway that converts kfzz14tsc x2( threonine to the end-product isoleucine consists of five reactions. Threonine is converted to variousxf4 zt2(z ck1s 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 on the rate of an enzymsk8s a:z fz-)gwc1+*g iu )aoh.g3ozzatic reaction. What is occurring during the phase labelled k-zi z w o :3+8asz)oh1uagcgfgz*).s section X in the graph?

  An experiment tests the effect of changing substrate concentpkmxf+g r8x /3ration on an enzymatic reaction. What could be th +mxx3g 8fpkr/e independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucine:b e8.t8v*lunan9xn v.



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

  Enzyme A (Enz A) was itz0f ni*k*nwe47 7hvwmmobilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph showz i7*w *0et4n7fwknvhs 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 of the following is the j/3 ek n*2gspkiahn 4;best way to keep e4 kjs;a*p3/knnihge2 nzymes active for a longer period of time?

  Which of the following describep *lp1mhtztgis+ 5q gy;;vw y+c7q q6;s some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A studaly0 ;ktkbm(1y was carried out to determine the effect of increasing substrate concentration on y ;1lta0(kmkb 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 wi9(-+jy)pf q p sak;maqth 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 activity of thm;9pkq)jyfa-s q pa +(e enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity,: 3tqfan2i7x4 vx /moi a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml wat :a4ixmn qv73x2ot/ifer 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. Inhibevynz3 ask :9cr..l0titors to the enzyme HMG- CoA reductase can lower n9:s0lykev 3tarz .. cthe production 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 followin( eqk mvg 2)2dw; viihhutbo/;er27:tg 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 metabot :0nhb hy)r-xz++z rllic reactions in the classroom and were given an experiment:+xhlrz0 ) ybztnhr+- 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 increasing temperature onau3j7ie- u q 4vxfe+/z the efficiency of lactase activity isj 3-f+az e v7/4euqiux tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactubojg. q;39r tase (Bg10), analysing the effect of o.qj9u3t b g;rpH, 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 opzc6ppj(yxw8d xxf07 ( y5 9zfind new drugs for treating patients with malaria. Describe howx o y7p0f(c 5zd8z6pyj9xw(px 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 concentration of5+u1q75u2my8eow uj3 cechqr an enzyme affects the rate of reactcyewr3h5uo 28u jc eqq1um7+5ion.
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 metabolize5vw4ap ml7(c reactions. Which type(s) of metabolic reaction 4vl57pe (amwzs are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differen)aoq1q u+: qlopku otdzh-b b 099mei2 7-gik+t ways the rate of enzyme catalyzed reactions can be measured)h1eiom du-q+99bzq ui ok0l- bt :qop2ak+g7 .
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 aa+,7pjp6ru haw9 z,wc nd extracellular chemical reactions, given one example of each typepua jz, 9a7,6rwhcw+ p 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.