Which of the following macromolecules describe am -ch(xgd0bvn**puj 3 typical enzyme?

  What type of reaction is4q pfh8bed35 wyr+rq 8 photosynthesis?

  What is the substrate for the enzyme lacta-u ujdls+dnhnr3 0dm+ a.w 79gse?

  Which of the following stages of c -forq*g.o bbvs;a9f;ellular respiration takes place in the cytoplasm? * .o;vb9;sqffab -gor

  Which of the following would not be useful in determining the rate of an enzk1c: 7ety ,2k(olc mmeyme-catalyzed(yt c,:o c1lmek7k 2me reaction?

  Which of the following processes may be describa1uyy9*vuhz07 o w4w bed as catabolism?

  Which of the following statements is best depicted by the figure belibi q9w42xk6. taloc .ow?

  Which statement about enzymes ishp693lftf4 s f not true?

  Which of the following graphs best illustrates the relationship betweey,1h2 eub uo(bn temperature and the acti,2 (uoubeby1 hvity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect enxl9,y;az1cq 6uqb8n8 x dyf*b zyme*xu6bnyx ,8clq 8dy1z;f a9bq activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed rear6s e5dx yyr ,xl3qt/8/hrb g2ctions. A diagram outlining the Calvin cycl rxs 5gl2tre r83x,/dqhyb6/y e is shown below.

The image below shows the catalytic sits+ +;h 55qtly+8cgau+f hhp jh(c n(6vo t.etae of an enzyme. The substrate is shown in black and fjanh(ocehqy(+5tgts6+ +v h c; h.tu l8a5p +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 ml*kp/ivym.f8 gu3 :aotk:q f7z2p nb0etabolic pathways shown bel*: fop2fna uizt7yg m8. b/kvqp3k 0:low? Letters represent various products of individual reactions.

  Which of the following describes thek; fs+hn/kfo+xz./p u role of inhibitors in enzyme-catalysed reactions/p +n uf.+z/xhfkko; s?

  Which of the following correctly describes photosynthesis or respirat6 -yq7 er,( ny-aewle:;erdjfion?

Many enzymatic reactione **y9s.z.ly*andd i:hhi*lz s happen as pathways involving multiple steps and multiple enzymdzn s*h*y y.hie:d*ll a.z9i*es.

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

  Which of the following best describes the inhibitor in tjwu 9gj;,pl va: 4os1dak9,q xhe image below?

  Which of the following statements are true regarding regulation by end-produde mny8k( e48mct inh4 8dn (myee8kmibition?
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 showsm +9 pg.gh5pmv the structure of the lysozyme enzyme. The darkened structure in black ip. 9mg+gvm5hp s 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 temperzy-yrze)z96* y j vmt(ature on the activity of the enzyvr6j9) yy- (ez*mzytz me 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 enzyonqcm04x 5: tmp*u9k hmes interact with substrates to catal9k tn:qm m4hux5c0op* yze 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 reactiojo; uuo rsobs7650so *ns can be measured.

  How does denaturation change the properties of an enzivtgvu1.xe,0vtw;e s s 1h ;:sqx2)n 9eglsp(yme?

  Enzymes play a role 6dm +9c7f5jq to 3oisgin catalysing reactions. Which of the following statements ar7moo dg its+5q96 j3fce 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 endotherms from ectothezmu ok, gyn9zs,7o rmr 17x(mgr6v.k7rms that have fluctuating body rk x rmn7. oryvz6og(g 77smmku,z,19temperatures?

  A metabolic pathway that converts threonine to the end-producj-4t ;i 6iyj4ivirw5c8 zk+ gst isoleucine consistik4i5igwc zs68 riv+ yt-; jj4s 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.
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 of0d 9(dreh1d u3 zp 4i3cfsoj5a increasing pH on the rate of an enzymatic reaction. What is occurring dc(sj3zop ur1d e d95ahd4i0f3uring the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate co4 j,y0or-p zdyncentration on an enzymatic reaction. What could be -4 poyj0d r,zythe independent and dependent variables in this experiment?

  The diagram shows the pathway that converts thr2vstxzm5 m* 6e *ml1hzeonine 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 and its act62we d 688ez*8*h csdmnuwdvu ivity was compared with that of a free enzyme in solution. The graph se8sd* un* wd2c86h 6uevdz8mwhows 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 fr*7qe qj, i r-(7qf vlbq0;omyollowing is the best way to keep enzymes active for a lr fi* (,b7vqemqj7q0 rlo;-yq onger period of time?

  Which of the following describes some types of extracel67 ;vu h5lmbhzw*mc8wlular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stvqvj, .7;aahklq/3 xdudy./7a jv3axlh ;qd,k qv was carried out to determine the effect of increasing substrate concentration 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 i9rkq/5 jnox2 nncreasing substrate concentration. Siminkjq 29 /n5xrolar 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 the enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a sky0f*zf yg 616;wzcpx tudent cut a turnip root into small cubes. They measured approximately 5 g in a weighing dis yz 6f1fx6gw*y0kp;cz h, 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. Inhibitors to the enzyme HMG- CoA hl(s56ennez( reductase can lower the prode6n (n lhe5zs(uction 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 are involved in ,n-o;kv 5*;v7 e crj /ndswf zrl9k6godenaturation?
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 were g+. s7kqxnjm;.rmmms )iven an experiment which demm;x.m7 )km rm .n+jsqsonstrated 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 on the efficrj yw* 6qo,klp o7l4-jiency of lactase activity is tested. Which is an app7-*,ol4jprjq6 oylw kropriate dependent variable for this experiment?

  A study has been conducted on ip8f 1) px,mmibp8z/tzvwkm; w(l./mthe activity of a specific lactase (Bg10), analysing the effect of pH, temperature and/,zz il8mtvwmip;1wmx.bp8f p ()/mk 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 for treating pativ/)n + okb8hatq-i2p:nk9bc qents with malaria. Describe how anti-malarial drugs arekbb :q-q c+8kn 2)phvtn/a9io 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 5s)uim7 kfres nan;40the concentration of an enzyme affects the rate of reactiemru074an)k nsfis ;5on.
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 ul8kn/zr 2r0 v,oad2x metabolic reactions. Which type(s) of metabolic react2n o8x ad2rz/0 ruvk,lions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enz3skqqmqtu7 b.*jp t57 in/ch *yme catalyzed reactions can be measured. .q/7qmbstk3h5 j* utncip 7*q
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 cx7s;t)v g2lpbq,/kz extracellular chemical reactions, given )vctl,b2s pq/g7;kz xone example 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.