Which of the following macr 1 pqo4/u)pdpqomolecules describe a typical enzyme?

  What type of reaction is photosyntbsm4x j /fg:ak74 zah)hesis?

  What is the substrate for th7f r3)igpnzj64 vqg 8me enzyme lactase?

  Which of the following stages of cellular respirax+b*b3xi: tuk98bjm xtion takes place in the cytopla8m3 x bb+ukb*xtj9xi: sm?

  Which of the following would not be useful in determining the rate of an x .b r.ogt8br6enzyme-catalyzeo.xr grt8 b6.bd reaction?

  Which of the following processes may be desc1hviyp 4-p:44ogdgaf ribed as catabolism?

  Which of the following statements is best depicted by the figure b::2 8q,wdk c wjvbxb+uz8qu. g5a e3hrelow?

  Which statement about enzymes is s:*a8ll-sjbbe959 gdbv4e r6a td 1h bnot true?

  Which of the following graphs best gawfs r4:* 1uwillustrates the relationship between temperature and the activity of enzy *uag ww:sf1r4mes such as lipase?

1.Sketch a graph to show hol:muzgf6f:d t t m2es f0px+:8w increasing concentrations of substrate affect enzym8fxg: tl:met 0s2:dp +m6fuzfe activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a serie)s s kjq-.:yazltmu zg572 en;s of enzyme catalysed reactions. A diagram outlining the Calvin cycle is s2le5)j7 :gkzna.q s;t- zyusmhown below.

The image below shows the catalytic site ohrjylo :k ic697y3 8syf an enzyme. The substrate is shown in black and is bound to the y ly8ry3 7jic:k9sh6oactive 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 descriptijrxl:+ e)4yvly hx0-jons of the enzyme catalysed metabolic pathways shown below? Letters represenlxl: y v)jrjh40xe y+-t various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-n6v c-x,3xybk catalysed reactiyk3n- c,bxx v6ons?

  Which of the following correctly describes photoe2 uyvr6fph0: synthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple stepia)80b q- qbeos and multiple enzymabi) 8ebq 0q-oes.

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

  Which of the following best describes the inhibitor in the image beloch a/msq/ ()5uu rm0;,jpqrxa w?

  Which of the following statements are true regarding regulation by er etb:a v2h1d 27;lgq, 4)7psxaxvdiend-product inhibition7srlph 4 :i; ad7t,ex) qv1x2d2aegvb ?
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 be:78apc b7z voqt vba /4i+d3;bjwh /enzyme. The darkened structure in blpd v4o3b7:b/t jve/7a ;iqhz+abb8 cwack 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 tempeg 7r(+7tblzsurature on the activity of the enzyme amylase. urt7+( bg7s zl



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 statementscz y:+(+60yh59wsx qykvynhc5yx*mx describes how enzymes interact with substrates to catx+6z s*x5+:kc9hyy w(hvym yycx qn50alyze 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 caa 2uog.m72 )fsy*od9x wmld, 2zhxxg0talysed reactions can be measured.

  How does denaturation change 4mt f+apj549i9r ikg2rvy+a nthe properties of an enzyme?

  Enzymes play a role i:jtc:c4 s tom;n catalysing reactions. Which of the following statements are tmt4 c :jstoc;: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 that6kdpyk5gsf*u 7 e 7rm: separates mammals or endotherms from ectotherms that have fluctuating bod*7:m 6 pygek fr57sukdy temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine consima6lsszk p i7yjv, qw0pny//e2by22( sts of l 22/kjp/iy( 2bzye n0spv,6 aqy7wsmfive 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 ). z+- wkoslw obki6hdpu6b1+pH on the rate of an enzymatic reaction. What is occurring during the phase labelled pwud+zk lski)b1 wh6o.+- 6 obsection X in the graph?

  An experiment tests the eff2; p-c-1z. +vsbmn0f l alktx6 kv1ywtect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variaxkpvym10sf1+ 6z a-tnlb.tc ; kv-2wlbles in this experiment?

  The diagram shows the pathway that converts threonine to isoleucin h,mn+ +txszza1ia7t-;zh 6qf e.



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 woo 6jf9z+s6y eas compared with that of a free enzyme in solution. The graph shows the relative enzyme acti o6osze +yj96fvity (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 o lt hqdv4 bi+b9zo9h0 ,5dfps(f the following is the best way to keep enzymes active fb z045ho+fvt idpb9h9 (q l,dsor a longer period of time?

  Which of the following describes some t;5b3 yf qnda1fypes of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomacu kbkq n,g2,malwhs9u.t4 *5zh. A study was carried out to determine the effect of increasing substrate concentration on enzym,k5gkub*2s tn4z,l.m h 9aqwue 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 ratew,adfr(g fwx*x ealew.7(j.0 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. Td.jgrae xf a .7*0x wwe(wf(l,he 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 activity, a student cut3h5k-y2)d 6dvppmvg c a turnip root into small cubes. They measured approximately 5 g in a weighing dish, addhp) 3cydv 2pk -gd65mved 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 HMc-qw 2(rl)cgrd- c df 33s7ctuG- CoA reductase can lower the prof sgcu-2rdcd wr(c 7t3)lcq-3duction 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 l4k3q1iih9j60 x abbcinvolved 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 mqq cq 9a4v:wp)r4ht2f6a wpm0etabolic reactions in the classroom and were given an experiment which demons 60qthp map qwqc4v9:f)ar2w4 trated 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,98e: tgytkl9y3 fwx s on the efficiency of lactase activity is tested. Which is an appropriate d9yf w8gk3ey ts x9,t:lependent variable for this experiment?

  A study has been conducted on the activity of a specificzhj rh,* q h+s2,chyo; lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lach; cyh s,qhzro+ hj2*,tose-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 pajtlsyut8pv 6)/o)gb xk- *5m ltients with malaria. Describe hy6 )pm*togj k-ub8lst lv x5)/ow anti-malarial drugs are being 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 concentration of an enzyme affects the rate of reac:kb xvm1u8*r:)s.uckg z (xd wtx *kx8 vk:sbdg:w. murc (uz1)ion.
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 syna3nzv bfcy16x0nt0 h 6thesized through metabolic reactions. Which typef60b yh 0c 3zv6na1ntx(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catk :(bj1di/y iaalyzed reactions can be measu( y ibadji/k:1red.
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 in0ck*; o 8vtebltracellular and extracellular chemical reactions, given one example of each tyl e*t 08b;kvocpe 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.