Which of the following macromolecules describe 6f3air s6fcu9 0k a*fra typical enzyme?

  What type of reaction is photosynth:goti* vu x6)qh 2e:zlesis?

  What is the substrate for the enzyme lactxv*v mzn*r*.e e,pxu8ase?

  Which of the following stages of cellular respiration takes place in the cytopct j3)gngaj9 n +8e0o vimf7boc( ce22lasm? o3i9j e (nte)2+0fov7bgnm 8cgcc 2ja

  Which of the following would not be useful in determi-x(t) zeesw2u0ei/o yning the rate of an enzyme-catalyzed s2)oi(ete/x 0-yue zwreaction?

  Which of the following processed w09yit z mlln 94eq;*()uyeas may be described as catabolism?

  Which of the following statements is best depictc; ldkr*am6a) ed by the figure below?

  Which statement about enzymes is not tm* jna vd)3 2(omjqqz3rue?

  Which of the following graphs best illustrates the relkw9d/:uqe/w.if*k e jationship between temperature and the activitywkjuk/f/9 eq .ediw*: of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affec/oq(/(z)qkz)qy fg 0o dswe. ft enzyme activitk/qzfo)(./q0 z y s(ogq fwed)y.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a se-*w g+0jed7kd onw:y kries of enzyme catalysed reactions. A diagram outlining thedn:ye g od-wk0+k* 7jw Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substra/ww*ms e0jx8 gx)px6 ma( tic.te is shown in black and is bound to the active 6cx .agm/ew wsit)0p(* xj8mxsite.





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 g:uf-5p a,(uu3a q i) zflo4yzpathways shown below? Letters represent various products of individual reay:og-f(f, uaqz 3u4al ip5u)z ctions.

  Which of the following describes the role of inhibitors in e1onl ej/4j9pcu.ce; z nzyme-catalysed reaction1o4celju9je .zpn/ ;cs?

  Which of the following correctly describes phd0x 8(xrkot /k4bea d4otosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and mmk rp)j3+ebo0j 9 pr.pultiple enze r93m0j jbppk)+pr o.ymes.

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

  Which of the following be0q gjagg.dn)phf g ;ie t*4 z1z(3dr lk*ul9v0st describes the inhibitor in the image below?

  Which of the following statements are true regkg i+:21hews darding regulation by end-product in:sik d1w+ 2ghehibition?
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 struct hnkn: )( i h64o-e.k;p ;gmcdgzdfeo8ure of the lysozyme enzyme. The darkened structure in black is the seh; .-kd;gh: gcd8e i)(mzo4fnpnok6ubstrate 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 dg.(w4xpa dk( effect of temperature on the activity of the enzyme amylase(gx(4pd wd ak..



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 interact with subsatg st +4ufhb/4gclxe(vq/:qx98 hs6trates to catalyze ca tev4(4ut98qhs xqbx /g6l+g/s:fhreactions?
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 f,/8.n atqz ooreactions can be measured.

  How does denaturation change the properties of an ebgzi-1*qsfq 9;qi1) znxuf d 0nzyme?

  Enzymes play a role in catalysing wo r1)q4xv4gb reactions. Which of the following statements are twro44g)vx qb 1rue?
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 ,rfe qcexlxmtfkh8xn. j8-1 ol1f.4fb tu51, or endotherms from ectotherms that havxxljfn- re8uqbfc11 t tex14 85,k.o .fhfm,le fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product :.;lg8d, ua+bw yaga oisoleucine consists of five reactions. Threonine is converted to various intermediate products sequentiallyb+g8ylw g ao:da.u a;, 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 iiqz k*v6 .wfgcq/,t,ov o 8(ktncreasing pH on the rate of an enzymatic reaction. (ftt /8 . ,*6koz qi,wvcgkqvoWhat is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzymaeha ydeb1/+0 ntic reaction. What could be the independent and depend+/ad eeb hyn01ent variables in this experiment?

  The diagram shows the pathway tk:aw spvo .;wk ,b,ud7u btw*2hat 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 immzw/ mjb3k,nuyzg8/* vobilized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relativev/nm3k buj/z8g*wz,y 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 denaturzys1j w azotk- /oljczd 8:b*4 j08y6aed. Which of the following is the best way to keep enzymes activ8a/a1b y:jd zo 0- js8k*6wctoy zl4zje for a longer period of time?

  Which of the following v4 ud tag.xdb1cfl*:v3 d9bm9umn35k describes some types of extracellular enzymes?

  The enzyme pepsin hydrolysest1+eapp,no:le63 sqn proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate conc:taeqn1 sppo 3+n 6e,lentration 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 rawl5lgd7:q vb.n/z1y vte of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C y/gwz1lvl.b q5 v:7ndand 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 enzymmory; .psio.4 e activity, a student cut 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. Thopoim4.rs. y; e 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 bt,9mp2d 8hh0ffj, utz elow. Inhibitors to the enzyme HMG- CoA reductase can lower the productth,,pd0 9jf2t8zu mhf ion 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 ia-sw68x tk;2unb 5idx n 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 metabol*3r; wwfdh (uxjn9 lc,ic reactions in the classroom and were given an experiment which demonstrated the effect of te*f( nw9wx3u; jl crdh,mperature 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 increas+ sww(pcfby. -ing temperature on the efficiency of lactase activity is tested. Which is an c + psfbyw(-w.appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a speci-;qh k6:xcd msxt6xwi bxsi yx(1p224fic lactase (Bg10), analysing the effect of pH, temperature and t2x2q im 1hsxi; :wdbxk xc-6s4y6(xp 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 z- ux9wxf y.0enc 4 qykb-7n.dpatients with malaria. Describe how ynnw cz -uy.-kfxd.4bq e97x0anti-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 affects the rate o5r 0zbil+b,w ff react0 li,rfb5 wbz+ion.
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 bros4u/ucdw yq5 u, v6ngk3nc9j w.m(b 1nken down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation react un5nnyw.m bj/w 9s3d( ucv,k1cg6q4uions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rat hb)jmhq -(hk4e of enzyme catalyzed reactions can be measured.bq h(-4khh)jm
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 chemical reactio jjtj9 k4u (wb)cn2yl2ns, given otu42jy 9b )wjk(l2c jnne 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.