Which of the following macromolecules describe a typical elpjju p lai8lm+e .). 357 jfpg;sby0pnzyme?

  What type of reaction is photosynthesi2v vvhic1p/ i7s?

  What is the substrate for 5wo,f,tf/ phhb fq hu)vg6o 5jo829cgthe enzyme lactase?

  Which of the following stages of cellul3ut :uuj(pyl, ar respiration takes place in the cytoplasm?ju t,upu3y(: l

  Which of the following would not be useful ig7a v vn9 ocs)27b(6fgkgjk*cn determining the rate of an enzyme-catal*j7 7 va(ccks)fk2bgg6 n9vgo yzed reaction?

  Which of the following processes may be described as cata0 b*0j8afz1i ofxa1iz 55oj qebolism?

  Which of the following statements is best depicted by the figure6bc,vj) w4ayy0oe2 oh below?

  Which statement about enzymes is not tg+hmfwd7 aj 5tyg02t 7rue?

  Which of the following graphs best illustrates g(p+ly /2avw29(ovq mmxc.:ccp huw2 the relationship between temperature and the activity of enzymes suchg.h2wval(opy ucc 2 c92q( m+mwp:v/ x as lipase?

1.Sketch a graph to show how increasing concentrations tj lpq*fq5*q8 of substrate affect enzymeqft*5q* lq8p j 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 reacov2l +fcs)+yk tions. A diagram outlining the Calvin cycle is shown belk2 )+vofyc+l sow.

The image below shows the catalytic site of an enzyme. The substrate is shown i;/vaga a. y l:hlg,d*zd g;qn0n black and is bound to thevqdg ynl;d*a; zhg.g/l, 0 a:a 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 descrw /dbd/q) m5j gw83wedx x7dh.iptions of the enzyme catalysed metabolic pathways shown below? Lettersx7h/3mw bdd5/x qjdgwe w)d.8 represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enza5mb0fae bqd68f)p v 0yme-catalysed reactioa m65aq d0be 80pfvbf)ns?

  Which of the following correctly describesfo-x akfscab0blpg-2fk 4 732 photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and mu .bacm1urf5 n5ltiple enzy nb1 5mcau5f.rmes.

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

  Which of the following best describes the )jmfm6hni8(;xtt6q( dthg/ zxj.ys 3 inhibitor in the image below?

  Which of the following sc* i4 m(mip 64we/7u9l oqybewtatements are true regarding regulation by end-product inhibitiie9 *7/qwem(b6w o cum i4l4pyon?
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 darkenek5t zigf*- g dq;jwl+-b0(b lumry :1md structure in black is the substrate and is bound atz5; -(qflkg0muidlb* 1+w y-mt: jrbg the active site.

Which of the following characterizes the active site of an enzyme?

The equipment below can be used to study the effect jn5de z7y4kqe4hz.7/ ;an7law0 oktjof temperature on the activity of the enzyme amd50z yen 7nok/;aaw7 .tz44 je lkj7qhylase.



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 zu /qkgnp7kj )ug6j-4how enzymes interact with substrates to catalyze reaction- qkj6 )j 7ungu4g/pkzs?
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 .t*e0 k:yyv+m 8 ghabscan be measured.

  How does denaturatiovwnn :dwzu3wz;/ e/6xn change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following st6szwf/ rc*v*muv*n(z atements arcmr6fz*s* / zv *nwu(ve 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 mam;sa )75 vl,d y8wqhlcamals or endotherms from ectotherms that have fluctu) lq;dyl85,w hv7 caasating body temperatures?

  A metabolic pathway that converts threonine l h;j/cozkiin p*8h1.to the end-product isoleucine consists of five reactions. Threonine is converted to various intermed.j /; zkn*1hlipho8ciiate 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 enzyma nnfkslw ;m8a/e m87t j2 :*bcokdtp./tic reaction. What is on not7m fwed/*tl:s.2j /8 m 8kpac;bkccurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate c 2 8cb708cp fs5ljkhzqoncentration on an enzymat 5bhslz82 k8p7fq0cc jic reaction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that cowsfy o4lh*hhq2s2c6i2v/bg.tu9 a o(nverts 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 o:fcm . du*(ba5,a4adisjzox 9 n a matrix and its activity was compared with that of a free enzo5d 4,j.*i : 9fasud(zmacabxyme in solution. The graph shows 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 eo amw ,if14zw)asily denatured. Which of the following is the best way to keep enzymes active for a longez1a)ofw,i 4 mwr period of time?

  Which of the following des.wwnu *v zxjef)f.+h6t4g 3macribes some types of extracellular enzymes?

  The enzyme pepsin hyj , ypa9h6pws-5 zzci*drolyses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate*pw6z9pc-z ijy5 sh, a 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 rat/bxwah8 /*y5ufhcl1 ge of reaction of an enzyme with 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*wb8y/5ul a chfgx /1h 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 cch gtn* dmoe;k )e-9ay.*b f+a turnip root into small cubes. They measured approximately 59nmd*ht*a c gbe)y co;f- k+e. g in 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-jxgd(/w/nr h *8kj*tu CoA reductase can lower the p gu*rjdhjn* tx(8kw/ /roduction 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 denati+k; )q +wn(nft.y upxuration?
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 meg-pvlhynx7) ;yw *vt8tabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperv7gw;vpy) *xl-nty h8 ature 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 temperatmy,d6. fzv+x9r9oxs wure on the efficiency of lactase activity is tested. Which is an appropriy+ 9mfxs,wv.ro z6 x9date dependent variable for this experiment?

  A study has been conducted on the activity of a specific lacta; +dkr4wcwm6 27c gnlvse (Bg10), analysing the effect of pH, temperature and glucose concent 74ccrnw 26+w;kvmgdl ration, 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 nat *8p89z 2nni sh*b:5jooep7qg 6nunew drugs for treating patients with malaria. Describe how anti-malarial drugs are being discoveret:ezj2 9p*675bin 8qon8u phs nga*nod 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 afb8zo-1lg 8. 8fhixjw f a0ebf5fects the rate of reaction. - x885.j1 e fhzwf8oaibfbl g0
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 +.; omfl7pz,rvr,6 dxyw(ojd metabolic reactions. Which type(s) of metabolic reactions are condensation re +d;7pj w z.f rol,rvyo(x6m,dactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the ratejtw tfq cal90 jl,l15r ;xu6r. of enzyme catalyzed reactions can be measurl0r9tx;cl jqlaw5rj6 1,tf.u ed.
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 reactio8c og5aiwui:h+r*u : rns, given one examp iag*wh8:o5r+c :iruu le 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.