Which of the following macromolecules descie *nssb t jnd:5c8a34ribe a typical enzyme?

  What type of reaction is photosynb;(y 00z5fkv8+w n xjtaf/xzxthesis?

  What is the substrate for the enzyme lac)k;q )+ki);w. womodfl- ewbdtase?

  Which of the following stages of cellular respirat np3:jt 5tmo(gi6cp0z ion takes place in the cytoplasjt pn6 :(cpzm305 otgim?

  Which of the following would not be useful in dete:logwswx0* w ,rmining the rate of an enzyme-catalyzed 0sxw lw:,go*w reaction?

  Which of the following processes may be q+fhfi8w.wd 7c):sg x1n *gzmdescribed as catabolism?

  Which of the following statem ;b16dlq,3 jrbmb7jel ents is best depicted by the figure below?

  Which statement about enzymes is not true?i9aw/ bhz5vr s),sr9a-xiel4

  Which of the following graphs best illustra17j (9gxltz+hosnz 9,b 4oxw vtes the relationship between temperature and the acnol9z9,sxhxwj( vt+1o7zb 4 gtivity of enzymes such as lipase?

1.Sketch a graph to showu47 ctrbu. 4d ld6fm*i how increasing concentrations of substrate affect enzyme activityuiu dd 6f7.t lmbc4*r4.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzmsov5rn+ 7 c:myme catalysed reactions. A diagram outlining the + 5om:7c rnmvsCalvin cycle is shown below.

The image below shows the catalytic site of an k*cs d+wkqvn+,5m xr d+* bf:nenzyme. The substrate is shown in black and is bound to the activvscbx:+d+w*mn*nd fk,q r k5+e 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 descriptionsrlye 8worsq+kj.0,3n;c +ca d of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individu s8+. jyo,0nk+ra;dl ec3rcqwal reactions.

  Which of the following describes the rolg xj3 vi;)8s/ g:sqcqme of inhibitors in enzyme-catalysed reactionm;3s/ cq vgq x:jis8g)s?

  Which of the following correctly describ ln3wqx9 y56;u)d*d; cjwczypes photosynthesis or respiration?

Many enzymatic reactions happen as pathm 8z*e*yq 5q7 htel016 xwr(wmsy x6gmways involving multiple steps and multiple enys*7 ghxr twwq lm5m 68*eeyq6z(x0m1zymes.

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

  Which of the following best describes the inhibitoxlt h775ood, ;ly0a0 hdjfds:r in the image below?

  Which of the following statements are true regarding re ogbn wb05m)8opvhnlb4 v .1o/gulation by end-product in)w 1 8bo0/b5.hp4ml bn vovngohibition?
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 +:g59mlpkpa b the structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bouk5l9b pam+p :gnd 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 te)h1 6 fk a, cz/uqq0crkhiu8f1mperature on the activity of the enzyme amy68hfiauq1kcucf / zh,)q 0 r1klase.



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 rv7;n2 36 zx4ec+aeo1fgn xbddescribes how enzymes interact with substrates to catalyze react; xxn7fzn1e2cv4d +r 6geo ba3ions?
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 ca2v kqg+e*tk m(n be measured.

  How does denaturation cha( 2ut*f bkc1 susb(o8wnge the properties of an enzyme?

  Enzymes play a role in catalysing woq5q /;7j +iuz9oll hreactions. Which of the following statements are tqujl7hozw 5/oq9+;li rue?
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 separwys1bu h5fwo 80j+ fr 56m6pznates mammals or endotherms from ectotherms that have fluct61r f6sj05 f5ow8uhbn wmz+ypuating body temperatures?

  A metabolic pathway that converts threonine to the end-c,+tfpxv;k552jo iqy product isoleucine consistyftx5pkqv;j 2c +5o i,s of five reactions. Threonine is converted 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 th(rb7ns:-bxl ve rate of an enzymatic reaction.vbl7nbr - :s(x What is occurring during the phase labelled section X in the graph?

  An experiment tests the effecto xrpug 5s.hdu/: q+e: of changing substrate concentration on an enzymatic reaction. What could bo+ :p :.uquheds5x/r ge the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonin.3(y-o8h p p.*sivwl ppwae f+e 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 hlk6j a:p4mdap8q(i. a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) wip:a.lp68m ih4djq (a kth 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 arelj8j l*v q6goczg0q7 + easily denatured. Which of the following is the best way to keep enzymes active for a lon jz0 jg86*coq7lg+l qvger period of time?

  Which of the following describes some types oit rtn/2fkt8o3dj4:; * lse hef extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in9j g l+gh;+i mv.o.2idxxxna0u5g y3x the stomach. A study was carried out to determine the effect of increagigx.xoyx0 iun3a g+m 2+5vj.dh 9l;x sing 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 enzym4 2 (8x7-euixvywf sqbxwfcen) e*r/+e with increasing substrate concentration. Similar concentrations of chemicals A, B, C anxw4cseu*w2 iy/n-fq v x7e r+8x)( efbd 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 enzyme actu ,*+g0 eurxhne4ooj6ivity, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighingeu4 g xhn+6u oe*0rj,o 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- CoA reducth:49p ou crf7m1 ses9o6 t)dfpase can lower the production of cholesterol.ph r 9uocfesmf9 :odt476p)1s


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 denaturat :wh x)b9fes:foree 43ion?
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 thexbk-aaf 1.j)y classroom and were given an experiment which demox)aa -jk1. byfnstrated 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 of increasing temperature -2a b vfs/l u-hv7u1iron the efficiency of lactase activity is tested. Which is an appropriate dependent variable for thisl av-i1/bvh2-uur7 fs experiment?

  A study has been conducted on the activity of a specific lactase na7t(j4wr ;p i- akgwoo6+ua/(Bg10), analysing the effect of pH, temperature / -rw+wgn akaia;o4uj o 6p(7tand 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 neehs7brli: zv3ader(77lrkpb9 h p6-v4d to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are r7h9 p she6 7vk alrb3r7-dz:vib(l4pbeing 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 concent q2waotq;qma *rf2./qration of an enzyme affects the rate of reacq * /fatwroqq m.2a2;qtion.
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 ds6 i (frxt:,tqown or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation reactio qtrt:6f (sx,ins?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyze bamrk 5dq.*c*d reactions can be measu *cq akd*5m.rbred.
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 r;xadwiiki17;oso d 3e4pt0+ 86sgeao eactions, given one examp+soi1e0;k stedoi ;47o6p aw8ix3agd 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.