Which of the following macromoleq/j2h ve*d xt3,a)xc ecules describe a typical enzyme?

  What type of reaction is photo*g4y k7fk*he5w dx z5qsynthesis?

  What is the substrate for the enzyme lact 3 gtyvnhh 1)w7ru-7 n0ppy,7lprqna -ase?

  Which of the following stages of cellular respiration takes place icyoj)u 2y a 6zl3j-s/yn the cytoplas6yc z-j2yl s3j)yuao/m?

  Which of the following would not be useful in determining the rate of an ea(+99iqw5p f kkavv1hnzyme-9p( iaqf5hw+v 1kkva9catalyzed reaction?

  Which of the following u3,alvl8 p8jn processes may be described as catabolism?

  Which of the following statements is b12uyum x2jfh*est depicted by the figure below?

  Which statement about enzymes is noty+1h w. gysdp( true?

  Which of the following graphs best illustrates the relat8glswiaw29e bfr z6dt v 8n595ionship between temperature and the activity of enzymes such as lipase? w 5zwsdlb 8 fn8ar2gvt6959ie

1.Sketch a graph to show hzhuiw pq j5h5kif 8.no5* +tz5ow increasing concentrations of substrate affect enzyme ac+85ok.h nqfz* wp htz5ij55uitivity.
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 outljw./2s evild)bhwsd jn 7b;; g,0pej2ining the Calvin cycle is s gs)2ehin.wd j pd;bls7ve20jb,j; w/hown below.

The image below shows the catalytic site of anmfmau:glla b .i0c0:ftd;-z / enzyme. The substrate is shown in black anfd; 0l :mgc -.tai0/ulz:bf amd 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 pathways sh(b ddz 7xdjeh) i)q7s0h.8q swown below? Letters represent various prodhd8w xdb)hej(qsi)0 .q7 s 7zducts of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed ra(.l+ fzel ra2m4ava9eactaz a.r(l9la2+am fv e4ions?

  Which of the following correctly describes photoo-cmyo4yo*8(0i f,h wkvp9kn synthesis or respiration?

Many enzymatic reactions happen as pathwayy 3 kvcd0)w1daiur (;q wh4gl)s involving multiple steps and multiple evk)3hu(il4d ydaw1r;w0)cgq nzymes.

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

  Which of the following best describes the w x2xe2ow2 :ohwu6d 2dinhibitor in the image below?

  Which of the following statements are true regarding regulati4 ;s h;0-md mue5x(+oewd bniton by end-product inhb(0mxte4u 5n;hmo+-;ddsew iibition?
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 dark *,jf;he(3au-qtc aqi e -tt1oened structure inhatteq,u3f* - ie atqjo-1; c( 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 temperature on the ac:xmaln.* f5 ;blw;i*psbg2v gtivip mgv; 2libfs;w nab *5g*:.xlty of the enzyme 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 statewdv8r6n40hugt )( iavments describes how enzymes interact with substrates to catalyze reaci8n6h )avg d0(tvrwu4tions?
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 catalyse:1(nzy c5:kaa cwc9be d reactions can be measured.

  How does denaturation change the properr3nmfe 9ec2:n2)r zfaties of an enzyme?

  Enzymes play a role in ca9n yq.ghbvmtsog *qb .wex;0ko(1 ;/ etalysing reactions. Which of the following statements are true?yxbk0/om sqt* ;n .1e.(hq 9ewvbo gg;
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 endother(l yr-niq.c *oa-mde-ms from ectotherms th o.r-md(-le yq ac*-niat have fluctuating body temperatures?

  A metabolic pathway that converts thnx/1d 8t b )o8 t.tf3vnjzcng+reonine to the end-product isoleucine consists of five reactions. Threonine is convert8+xt jog 1)dnnv3 t8.bzcnft/ed 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 of increasing pH on the rate of an e) sloc d3 .)mhak;w 0ji .ar;;d8lgchqnzymatic reaction. What is occurring during the phase labell.dwd0hhgcorm8s)a;clk3q ; ja; i).led section X in the graph?

  An experiment tests the effect of changing ()bz1 h 5awfdkf i;3kts 4+qjjsubstrate concentration on an enzymatic reaction. What could be the independent and dependenfkhqi3+41z 5j(d wksbt jf); at variables in this experiment?

  The diagram shows the pathwanh8c-s4qd/*n lnjc 5 ey that converts threonine to isoleucine.



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

  Enzyme A (Enz A) was immobilized o2 oc4qrnat+6 oi-e8adn a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relt6one2ar -oc da8q4i+ative 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. Whi9qeilofz:)u 6,n+wdi8gft hn6 r4 hq3ch of the following is the best way to keetnqf:)u w636ofiq9l ghhz 8 4r+n ,idep enzymes active for a longer period of time?

  Which of the following describes some types of exd 7h5mecm5yt. tracellular enzymes?

  The enzyme pepsin hyz 4wv1f0/e2io, wvj tgdrolyses proteins to release peptides in the stomach. A study was car0t o4,fvg2 j z1eww/ivried 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 increas f.cny9q1w hedqat 77w(7bq;king substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monitored ywa.1bknehtcw;q79 (q 77dqf 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 student cut a turnip root into small cubes.qd9* 7gb:zevma pt87y 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 thet b9dv8* qgemzy :a7p7 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 below28sfxc4.nkjr xw*laj-5ah d9+m 2jkd . Inhibitors to the enzyme HMG- CoA reductajhjwlk2xr n5*8d mck a+s j.d 2xf-4a9se can lower the 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 following are ie*h,(a2pxgg u nvolved 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 rea,r40qorur t, actions in the classroom and were given an experiment which demonstrated rau,q 4r0otr,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 osb;.zn cu6:9z g0 h1ib;xgcldf increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate d c6:0 us.lb9nzi;xdbc1z ghg;ependent variable for this experiment?

  A study has been conducted on the activity of a specific lactaseg6e62yo ;kmh s (Bg10), analysing the effect of pH, teoe ;symhk g626mperature 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 for trey n27jw-1oiuw ating patients with malaria. Describe how anti-malarial drugs are being discovyn 1owu7 j-i2wered 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 of an enzyme affects the r 3s8sar. :dj.fsr bg,oate of reaction. fbsas:d. js.,o8rrg3
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 metabolic reactioyk 8+8kk6kc8nufb )w dns. Which type(s) of metabolic reactions are condensatifyk8w+ ubk8nd)k8k 6con reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate ofq i;/cy,cx4 yk enzyme catalyzed reactions can be measured. ;qyc,/4xk yc i
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 contrab(n2pifnq75 dqq/s x ,st intracellular and extracellular chemical reactions, given oi2b qn5 qd 7n/xs(qpf,ne 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.