Which of the following macrom-0y5r 9hyp a,o9jev cmolecules describe a typical enzyme?

  What type of reaction is phr6fn+: ulss,;e y m/j ae/-tjtotosynthesis?

  What is the substrate for the e: awv c8zs (ntcw.-8*nm yqnal :(1cpanzyme lactase?

  Which of the following stagjxypulxmmi*2n.g :* hwq0 -n5es of cellular respiration takes place in the cytoplasm? *.unj0n*iwypx-l m2 g: xqhm5

  Which of the following would not be useful in determining the rat,dinw x vs8:d*: krbxsl4g-1he of an enzyme-cawsn -bdhv s4 :g,dxk 1lrx8*i:talyzed reaction?

  Which of the following pro/ jqlsjdd+y dg) 3sd++iey (2scesses may be described as catabolism?

  Which of the following statements is best depicted g7 db3oh:/y*z v o7pg9:by+pxv bv .ezby the figure below?

  Which statement about enzymes/nlra dv)naqnq4a/5)z)*ya sixdq 81 is not true?

  Which of the following graphs best illustrates the relationship ncelk3n:2jfe w1+q;p between temperature and the activity of enzymes such as n2f pl;cwekn+ jq:e1 3lipase?

1.Sketch a graph to show how increasing concentrations of substc *caz6f-n5v1,+cn.0ou smlp hxq lq9rate affect enzyme activity. mcoq+nz.x s1ncc *h fl0-u a5vp9l ,q6
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.54ebrfwv l fs59tt1:5hs -r po A diagram outlining the Calvin c:spvte 9r b-54 flhwfor t15s5ycle is shown below.

The image below shows txwuuy)j* q: p7ky50 adhe catalytic site of an enzyme. The substrate is shown in black and is bound to the pwuj0)57k aqy*yxud: 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 th fxtn0*w)6 qn7*db boue enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reaction fo0)q**ndw67xbnb tus.

  Which of the following describes the role of inhibitors in emfudc 26d40ods zlf8,/ / uafknzyme-catalysed reac4uf ldf2f0//8dz6 cmos ,u kdations?

  Which of the following correctly describes photosyntwj*,n0p(m0 c c+ nscuihesis or respiration?

Many enzymatic reactions happen as pathways involving n 5ykzzj/f- k;multiple steps and multiple jzz;fn/k y5- kenzymes.

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

  Which of the following best describes the i7:2m l7zvscnknhibitor in the image below?

  Which of the following statements are true regarding regulation by end-pr:fae45ub 3p xf-bk ic+oduct inhfc3f:eu+4p- k b5xb aiibition?
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 showspk4*,+ * oycv(bhfsiql 5s)gx the structure of the lysozyme enzyme. The darkened structure ,o hslqgiy *f5s)xb c+4(pkv*in black 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 t0ogcpt5dtlyy ;/9 d/u 0pe.nbo study the effect of temperature on the activity of tybdcguty; p.o d e5/t9n0pl/0he enzyme 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 statemel* awi lfihf/a6 6h-zrtu:;- pnts describes how enzymes interact with substrates to catalyze reactio6wralf- u/i;*lp z i:tfh-6ahns?
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 measured.h e5umu 6cs ixp4o;0u3

  How does denaturation change the properties of an enzyj/2kvbjbw- +0 h cq(xbme?

  Enzymes play a role in catalysin.6bfjrp pcwv7iw(d 2 ig,7l 2dg reactions. Which of the following statements arwjw(c2f7 2di.r 7,6 dglip pbve 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 zv9iijwe 9.i 6or endotherms from ectotherms that have fluctuating body tempez6vii99.ji ewratures?

  A metabolic pathway that converts threonine to the end-prodmvytmka-(8 nt7h593s+ h cyf3ntn2o c uct isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleuc m+foannh-t32tcc( vsn 9yy78t k5mh3ine 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 enzymatic reaiz3w54jd -fq3v,nj93ua+p r* p7 lhcys er5lhction. What is occurring during the phase labelled section X in the gr- pclrie + sv3h5flq3nwr*h 4jz pu9y5j73a,daph?

  An experiment tests the effect of changing substrat ig9)78ypcwdax14 jp/7 5)y xws rtnzse concentration on an enzymatic reaction. What could be the independent and dependent v pw)syn1i7djg58a 4yrpct) 7 zxwx9s/ariables in this experiment?

  The diagram shows the pathway that converts threoninin ):bx ,ohy u/;)gqdj l:.xzle 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 activity was compalmod 8-mw5/lrx bnz r7 e+-r i0trat8)red with that of a freebo/a l r8r5 zl70re-8i dtmw)+rtx-mn 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. Which of the follow7(ps * h6dubpaing is the best way to keepd6psh b( *au7p enzymes active for a longer period of time?

  Which of the following describes some types of extrc ey cl(-.do(oij,x2d0, dkcaacellular enzymes?

  The enzyme pepsin hydrolyses proteins to relea y6ocgcfgn *h g1cgpw3v f/)4/se peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperat p 1cogywg/6c ncgv/)3fh*fg4ure 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 increasing substra csy++z olb,2ru7n(pm(cafu5 te concentration. Similar concentrations of chemicals A, B, C and D were added independently to thym2,p + cbsfcnr7 zl5(+ (uaoue 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 a(qf:iz6 f 1sn6wrv s5nctivity, 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. The homqssfwr6i5n6:fn (zv 1ogenate 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 en70gx:a3 + bq5bdnafkdzyme HMG- CoA reductase can lower the production of choles q kda7n5dxa3b +:0fbgterol.


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 inv q+z3u gbm19i3krp n1aolved 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 metao0 0s(jl o xg935yxnjbn(vtl/bolic reactions in the classroom and were given an expe(bv/jx0 (o95n xlot y g0njls3riment which demonstrated 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 temps7 ic6ny v(j:cerature on the efficiency of lactase activity is tested. Which is an apiyc 7sj :(vcn6propriate dependent variable for this experiment?

  A study has been cond+: c.camee2q ducted on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactose-fee2 :mdcaqc+. ree 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 :o p8gv2qg / ,7gpqeajtreating patients with malaria. Describe how anti-malarial drugs are being discove7 p,va qoggqp2/ej g8:red 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 thxk l )rm64w8 0v3ctrqae rate of reac v3 0aqrtw8)crkml 64xtion.
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 h: (14o 4 cw.nqaqm0dn vbl iar8ey;w-metabolic reactions. Which type(s) o c el 8a 0n;ovihr aqmq1dyw4nbw.(4:-f metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions canwxzp+ 4mi 6v+j be measured.6z4i vm+wpj+x
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 a ;/k.;f wwu7glu)gmqreactions, given ogak)m/ q ;;w .u7wlfugne 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.