Which of the following macromolecules describe a rk3pr bi5tqx2pf dg7h)i9 20jnfs t +:typical enzyme?

  What type of reaction is ph2yhlsbt.; x k eupqoi)a e686l66 x:rnotosynthesis?

  What is the substrate fojo*q5*kipj dl/ re6x- r the enzyme lactase?

  Which of the following stages of cellular respiration takes place in the cyt7 iq(0hfgdkhe0, /n qhoplagqh0,0 7/ f(hnqkdehi sm?

  Which of the following would not be useful in deter)qnibby9 :g+vs-3 l )d ez.ylymining the rate of an enzyme-catalyz3 dy.lvi zg-q:ny eb)y) slb+9ed reaction?

  Which of the following processes may be described4m+ljo8 3zz8 9h olhgv as catabolism?

  Which of the following/uk:a3cn zu.u once/ cat;q)9 statements is best depicted by the figure below?

  Which statement about enzkm hr;9bd/jdj kvnuusi.x, ;mijd+e:4 2 (7 noymes is not true?

  Which of the following graphs best illustrates t*eetj4c;sh f+c 7go; nhe relationship between temperature and the actic;ejtfh; 7 4esocgn+*vity of enzymes such as lipase?

1.Sketch a graph to show how increzowr,5fj m)zyd8*/9dj,a f spasing concentrations of substrate affect enzymwdaf,pz/m* o9) dzsyr5,8 jjfe 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 reactions. A diagram outle1(rl6rbn p+pp i( . )d9ujkblining the Calvi 1lp)bjul6.rde (9 rkbp+n p(in cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown* *;di bp-k;m1fkgj/up cl+ib in black and is bound to the active situ fbpbd/kgk j-mc +1;lip*;i *e.





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 catalyevj8dhw+7y ar5 6 mdrgq-5d0esed metabolic pathways shown below? Letters represent various products of individual reactiod5 6-5qeyavh wgdm 8r7+r 0ejdns.

  Which of the following describes the role of inhibitors in ens bxtd5 j4h.+mzyme-catalysed reactio5d+sx mt h.b4jns?

  Which of the following correctllc nd12o22ui545y( e6 ngddz :nxz bbuxe8wf)y describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving /2ay:mv ge0/lqzsl hzp*/p 1wmultiple steps and multiple enzymesvpey/ hpg1 /m*lzs0a l/:2wz q.

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

  Which of the following best describes the inhi 4k8siii y2- )zzku:uzbitor in the image below?

  Which of the following statements are true regarding regulatid n v b-he;t6y(pnea35on by end-product iy(h-;e5n6b 3v d antpenhibition?
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 darkened s knujhfn; , :b)avne66my (hg;tructure in black is the substrah ngyh j;nam nbv6;u:() f,ke6te 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 activiu2b 1g)g7x hhq8r9oum4dc;b0 k m f2s ilwg-r)ty of the en7 gs9b 2qlk -4d h8iob gmcrmrhg;u0u2)1)xwfzyme 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 deschrth o( ;42txhribes how enzymes interact with substrates to catalyze 4;hrtt (hxh 2oreactions?
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 enz+s.ffn 6 no4owyme catalysed reactions can be measured.

  How does denaturation change the properties of an enzyme? pu.s02nm,+fds)xmhkr nx 5xex wt9(-

  Enzymes play a role in catalysing reactions. Which ;pjfrkldz3w x2 n 664vof the following statements are6v l xfr;32zpj4dnk6w 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 ectotherms i1fw1gp k- m4 szbx0b7that have fl4bzxigs-7k 110 mw fpbuctuating body temperatures?

  A metabolic pathway that converts threonine to the end-productz mijax(fhm x(m9,v10 isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by z hix(j1fmm,( 0xv a9mdifferent 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*0j jk wvkd7c. the rate of an enzymatic reaction. *. dc jv7kw0jkWhat is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration ont0 jy8w.6z,;, aynlyk jzmo- x an enzymatic reaction. What could be the independent and dependent variab;y oywjz6,ja. ty0n ,kmx8zl -les in this experiment?

  The diagram shows the pathwayv(oj:b2:p xp 9j*igog 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 on a matrix and its activityz9ys. .d 3c5f9qreq+cxrzs9 f, 7tb ro was compared with 9 cfsre brz.3,fzq57yxrq9sdto 9c+. that of a free enzyme 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 easily denatured. W63j3d+fx l4d4zqe oca hich of the following is the best way to keep enzymes active for 3o4 j+ad4 6 z3eqdflxca longer period of time?

  Which of the following describes some types of extracel d 5.c u2qh4g;oxhqfzk+kb1-xuk0kc4lular enzymes?

  The enzyme pepsin hydrolyses azslw ycy: z i3)2,(puj/6u esproteins to release peptides in the stomach. A stud upy/yusw3 al2z,cj:)ies 6z( y 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 ofppm dow6 *iojo)- .kd/ reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added indeo * )po-wmd.di/o jk6ppendently 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 ak xt-1t(qpk,w ctivity, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 mk-p1kwt x t(q,l 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) esk m2q xmy:b 5vf0;i7yi9df shown below. Inhibitors to the enzyme HMG- CoA reductas)eybm 20f x5:;sdkmyi9iq7fve 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 involvedtmm2 p p46* g5trqod*q 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 reactions in the classroom and eb ow+d:z0(6+dv;d0b j nc ftgwere given an experiment which demonstrated the effe zc0 +od6jwvt0:+bbfdde( ;ngct 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 effp-9ihm qkd+0))k ui5lprfn9m b8ps 6 piciency of lactase activity is tested. kprfb 5-mp09qp8n)i6l) k + 9spmihudWhich is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactcpj8++w y ;hghase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may pothy; g+cwpj+ h8entially 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 patie)* 0n2i2 wgi 7onfegzhnts with malaria. Describe how anti-malarial drugs are bei oi7*0ngzge )h2 fn2wing 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 increasin a +yksexcg7l0 zlnp o. w.o+ay2:k:,pg the concentration of an enzyme affects the rate of reacgz:yn a xcpkl.7yo2eo.a0lkw++ ,:pstion.
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 bh2i 16fw,d p xkza86vor synthesized through metabolic reactions. Which type(s) of metabolic reactions are coavbw1 82 xpf6h,d kiz6ndensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be hj/7 u 7kaeljww9ip62 measurewuhwplk9 j/ji2ea 767d.
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 chemica2 xne::o5by cgl reactions, given one example of eax:b5cg: y en2och 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.