Which of the following macromolecules describe a typical enzymcy7 -1*s mkh3mis1ktme?

  What type of reaction is 3dx(u/9ofcuw photosynthesis?

  What is the substrate for the eb*.3 cpp o rv)l anutap25(4v* n3bgcvnzyme lactase?

  Which of the following(5wcribon(*; j j9eoj stages of cellular respiration takes place in the cytoplasmj9br5*((oi; jojcwen?

  Which of the following woup mz:5 e.7i*hked jw/1ng(ywlld not be useful in determining the rate of an enzyme-catalyzedwy d /5mjp1k:7wzi gene*(lh. reaction?

  Which of the followi fmj)q;pp9 /eaq,+w s5 ff.cja3;olhqng processes may be described as catabolism?

  Which of the following statements is besm4t7 65hdbe/bbkhi /f;v mo z5t depicted by the figure below?

  Which statement about enzymes is notwy,.nx7x +23jw kfb ph true?

  Which of the following on3 1.;hl6t;wc4 cexhkvcuuu hd9q/0graphs best illustrates the relationship between temperature and the activit0uwcuekqu o. h;dh3nvh/;xl6c t1c49 y of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of 4,h ph9voj/y o-d k-j/wwkn7 hsubstrate affect enzyme v/, j-j4 wod7k kh-wphhn/ o9yactivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reu r2;wttem6c2qk16 jzjdej7w f+q4dw u v6(o2actions. A diagram outlining the Calvin cycle is shown q;o m 1w6tcuj2fqedverw2 k 2wdjz4u+7( 66 tjbelow.

The image below shows the catalytic site of skq n 9ckk.0f7ugy br(pp;95k an enzyme. The substrate is shown in blaf r uq9g9.ppknkby(5k k;s 0c7ck and is bound to the 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 the enzyme catalysed metabolic pathways show3gw5a aqyr7mqvw6hh*lesi;( 0 qb +i .n below? Letterh.+;i5qhsr0eqa v7bqyg*m a6i( w3w l s represent various products of individual reactions.

  Which of the following describes the rolemu-82wofuwjgsx4bdiu l ; m k3-+mcw3t 09yr9 of inhibitors in enzyme-catalysed reaction4o;r2 mjk w8m gw iy dw33cmtubus9x+ulf--09s?

  Which of the following correctly describesno v1 i*o3 ;svhr.fa2u photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multods7hhs4y 1g4 ):b/rk v.tpub iple steps and multipl4pr4s bok :d/guhhytv b) 17s.e enzymes.

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

  Which of the following best describes the inhibitor in ;punl-0z- 6 .0qei0 5l- hhvjg yovswqthe image below?

  Which of the following statements are true regarding regulation by end-produc h,8s.eaatt *ah;zsk+ t inhib,t ; ash.k* tz+seaha8ition?
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 str)sy9:7wfcnqwl2l)fr- d ic2ey+o0p n ucture of the lysozyme enzyme. The darkened structure in blacklyy- 2w +0s foiqec rc9f l)n7w)n2:pd 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 to study the effect of temperature onnqc4am/ b.ocs-rtst4b c3 w/. the activity of the 3t./ .bt-r 4a nq4mocwsccs b/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 statements describes how enzymes interact with substra 31puwyx )s6xhu oy0(utesx1uuy)pw ho06uy(x 3 s to catalyze reactions?
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 reac;c b. -qk2 e hq-cm 4fuhjyew2dqm74g5tions can be measured.

  How does denaturation c 2g( kb7z-n//ou bozcmhange the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stateme or;4+8xvhnt uh;z0f 2qei8pt * 1vtymnts are truep v;uhziohyte2 1*f0r 8 4;qxn+8mttv?
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 sepw9mkvxll +ki:tlx+6 0t rxq: 6arates mammals or endotherms from ectotherms that have fluctualvkxt x+ : i6+wx:90rmtqkl6lting body temperatures?

  A metabolic pathway that converts thfg8 w42xk, kchreonine to the end-product isoleucine consists o2 g8,fw hx4ckkf 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 incr8j y 4ufn3-dhueasing pH on the rate of an enzymatic reaction-u dhfy38 unj4. What is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of cham2n:ffh( d /cykf5k*anging substrate concentration on an enzymatic reaction. What could be the independent and dependent variables f*nk kyfdc2fh am5/ (:in this experiment?

  The diagram shows the pathway that converts threonine to isoleuciner 6(0:f )v ymguei0t6tm 3ewmh.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobilized on a z g9 wyanzhtwx0-7 h60matrix and its activity was compared with that of a free enzyme in solution. Theh0w7ag y-t69 z0xwhnz 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 following is h 5 i0w)fmewj7pb(m5c9j/r* at+d fqythe best way to keep enzymesd m)+ ra5fqp0j *c7eyf/wm59 w ji(thb active for a longer period of time?

  Which of the following describes some tyyjp n+go2:uo )dk+2 wlpes of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stuf8whemz qob*6nm 2c16dy was carried out to determine the effect of increasing substrate concentration on enzyme acf zbq6wh2 oecn m*618mtivity 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 enzyme with ibvpoyk*jjm;g (8l 1j:ncreasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was mogp *l:(o1j bjkjy;vm8nitored 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 enzymyp; b m2a6vambt9xj;,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. The hom mb;vpx2amt 96yaj, ;bogenate 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 tp,qfl(b.4 2 uxff c*fro the enzyme HMG- CoA reductase can lolfb,f 2.x(4uqc*f rfp wer 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 involved in den)vniu p( r,hl bwe+jw*n,s:g6aturation?
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 metabj-,ouy acgp : 0x*kba7olic reactions in the classroom and were given anap*,yx7bk-au:o 0g c j experiment 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 increasins+ lz:fqg v(1kg temperature on the efficiency of lactase activity is tested.sk+: 1(gvlqf z Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activit5 eosdhh3s;vxm:9+up;qz j6*yn rw7y wr6 we 6y of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be usjuhxnw o67y 3r wew;6: ;mpsh*69 se5 zv+yqdred 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 patients with malarivq(repjb5 0se ( 4twgqiq2zc;a)l:. ma. Describe how anti-malarial drugs are being discovered with new technolo.a(ptsz q05re2 i;wbqjvglm)eq( 4:c gies.
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-l0khbyu7 6r)e/ztx x/9- gxvou:p bsg the concentration of an enzyme affects the rate of reactio:x opb) t7v9-h ugz//e-ubsxy xr0 lk6n.
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 throughls *8 9ztw5rb,v4:il6cesb v v metabolic reactions. Which type(s) of metab8bl4rts v9w ves:i6,l z5* bcvolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be ma++jn*zu6dhi9 h o6 omeasurzihd6u9mo nha+6* +j oed.
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 i x1 y/i3f8 rym.3w8mmabk/kiok2p g 9untracellular and extracellular chemical reactions, given one r8p umx .mi y2k w3y3mkoagk/9f /18ibexample 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.