Which of the following macromolecules describe poec i6)8px5)wl5n bw -bta6 ya typical enzyme?

  What type of reaction is photosyn0/wwc k; fxl7+o7qzgm thesis?

  What is the substrat ;3sq9k zfqhk ez-- txqq0oi/.e for the enzyme lactase?

  Which of the following stages of cellular respiration takes place in l g,gf4rp;p8jthe cytoplasg8 pjlrf4;g, pm?

  Which of the following would not be useful in determining the 1v jqt- z(0ldbsp9;hp rate of an enzyme-catalyzed slj1;t (dvpp9-bzhq 0reaction?

  Which of the following process af3.iv ij1midh*cvzi r;y(4-es may be described as catabolism?

  Which of the following statemenv/r25hxo:t ai wc 9l,j.dte *mts is best depicted by the figure below?

  Which statement about enzymes is not2 f0qbs xl17sl true?

  Which of the following graphs best illustrates the relationship between temper j,(pa,3byh1( guvl6grl7otoature and the activity of b,(1 g7lo pvhug l3,r6ay(jotenzymes such as lipase?

1.Sketch a graph to show how increasing concentrag0z1b6 4e xk-m dp0g gsbyd;mc 3t-t:wtions of substrate affect enzyme activbmb ;g1pdgc-stm3gk6:0zwx y -4ted 0ity.
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 outli gxok7fta)oc j t-w,,fbg pd4(i4z)7rning the Calvin cycle is shg k44)ifdz )ca- j,wx7rtop7 f(bot,gown below.

The image below shows the catalyt+ (hzvsgiv 5 finj u,ct625c:bic site of an enzyme. The substrate is shown in black a ,2vifz cn:c tu(vshg+b 6j5i5nd 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 catalysedx6,3stf 1izen metabolic pathways shown below? Letters n 1ie z3tf,x6srepresent various products of individual reactions.

  Which of the following describ il -h rsn*63:n8 7zkmr+: -fo86lrporjfae byes the role of inhibitors in enzyme-catalysed reacti6 o3jz+ 8y me r rip-af8lbr-lk*o7s6f hrn:n:ons?

  Which of the following correctly descriq ury4uovo6*-lrt l93x-j9 ;tmkof k4 bes photosynthesis or respiration?

Many enzymatic reactions happen asl wwz 71t0ttz tmev;/ rb /i8t3en14zh pathways involving multiple steps and multiple nt / tl1z7t/wwz0vh i4b8r ;mtetez13 enzymes.

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

  Which of the following besqkv h ):;qmk:a,/4rr torma; gik+k1dt describes the inhibitor in the image below?

  Which of the following statements are true rbg ix5p0k bi68bpc8i)z.wa 7h egarding regulation by end-product inhibiti wz i58g6hb0apcx .7bikp)bi 8on?
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 structure1t yuma sur/.q) 6fw ++o+yuaf of the lysozyme enzyme. The darkened structure in bla6s /y+yqw+u)1 u.a+ruf om ftack 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 to r3qkz(*fyz 3he activity of the e( 3zz qorkfy3*nzyme 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 enzy0kym 8tybjq 9c8;wj(ymes interact with substratesy98 tcy8qkwjmy(j 0;b 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 can be measu cp3xzt o8h9:pok*eri xq7c71red.

  How does denaturation change the properties of c5x q b/n2/phtan enzyme?

  Enzymes play a role in catalysing reactions. Which /6 s( 2ekzwohkof the following statements are k/6soz(2h kwe 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 mammal)aae:ab my(f/ h;aeiba2 /j,us or endotherms from ectotherms that have fluctuating b )jm/( ,fh ie/buaaaba;: ay2eody temperatures?

  A metabolic pathway that converts threonine to the end-product isol9 bm17g6pl adneucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes befo9p1bgm7 an ld6re 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 o5 )b)d3 0u)fxq qpj1u*xm lhyyf an enzymatic reaction. What is occurring duringxdqm*p5 )u0)yuq yjh1f3x)lb the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate c hvtzgq96ufjr/b(15 uv ma2)rjkk:m(oncentration on an enzymatic reaction. What coul2k56:kvf hq ()bu(m1 mrv zujajgrt9 /d be the independent and dependent variables in this experiment?

  The diagram shows the pathway thazl;,g13 zpln ncbjcnk) 9ky 5-/fgz6 ut 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 on a matrix 3gdcbpl (7e / daof*9yand its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with* g 7pbldy3 aec(/dof9 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 easil tla5c 4,9rpgjy denatured. Which of the following is the best way to apr5g9,c4tl j keep enzymes active for a longer period of time?

  Which of the followinr 6osy2ff8m,6i:yr8k cup /d og describes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins i;c, n. 4p-seonfmc)a to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant tempenecp m.4,fna)-s coi;rature 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 increa sx-u5fw 27rye8jeu; dsing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monits u8udx j ry27wf5;-eeored 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 studente du0uq+ 9dn0zx:on/x cut a turnip root into small cubes. They measured approximately 5 g in /nx9doqd:z n 0x e0uu+a weighing dish, 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- Coq9+t5m kcslk)5h hh0)kek1 d x 0ea)ezA reductase can lower the productio1k eh0d9 5 q5aez)0m)h h s)t+kekxlkcn 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 denaturatip w(,0w) nmeobon?
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 metabbc sa8n - lium9273cntolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolicb3 7mns9ctniu ac l2-8 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 ojn -bs:y4b .p,mzq ,xbn the efficiency of lactase activity is tested. Which is an appropriate dependent variable for t,z - .nbbmbp:q ,4sjyxhis experiment?

  A study has been conducted on the activity of a spe,yv : k:u)ucrk:fr9bb cific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lav ku)r 9 ,:uk:bfy:bcrctase 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 for6g/ o9is4owg aq6 2pzzwsb :1d treating patients with malaria. Describe h zibwagswq9 p: o/1zg 42d6o6sow 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 of an enzyme affi,z8(j9n a(xws7 vypqsd,rk4no bs4lh5m2 8aects the rate of reactiok s(dzn9wrm 48,axs8( y np,7lj5o4haq vbs i2n.
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 throy5t0v 0s wi 3z:x cds9k(zbno;ugh metabolic reactions. Which type(s) of metabolic reactions are condensat9y tzn ;d50kbxc(ozv 0si s:3wion reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions canrg: p5y zo ku9h-k/ds4 be measur4 :o dhgr/kys5z-up 9ked.
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 extracellular chemigavhrf 72 rx:-1ci3qpuris 87 uy6l)v cal reactions, given i:cfaxrqi h y l68vuuv3rp 72-gr)s17one 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.