Which of the following macromolecules describe a typi/suqmzb2 t2dwb o7,b) zca9+ qcal enzyme?

  What type of reaction is photosyj.mu8-ehx6vy b6 6pylnthesis?

  What is the substratu+4ea)* 0oefm; fjy noe for the enzyme lactase?

  Which of the following stages of cellular respiration takes:e wfme3o2dym5q , (ev/ h*qgx place in the cytoplasmxeodq5 hmvwe gyf(3 2q m,e/:*?

  Which of the following would not be usefbj5uoimkr f0 5 37zsx8vz48lt ul in determining the rate of an enzyme-catalyz x ot 5zjliu4r03 kf8v8z5m7sbed reaction?

  Which of the following processes may be described a bihtxdm0zv-x/ftz8,ar1 kp4l712x fs catabolism?

  Which of the following statements is best depicted by the figure belo-qi:c2xw h2 (pjk3nlwb* .euuw?

  Which statement about enzymes+ .yi4f r1svp0(flute is not true?

  Which of the following graphs best illustrates the relationship between temperab p.ym0c;0 fb wgd. njzx;/zdam457crd:ph.h ture and;fzd yahrdm.c p c 7b0g n.m.:0b;xz/jhpd45w the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concea :/q uksp.5ysntrations of substrate affect enzymes.:5uk/pa yqs 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 ra5sdpww 4t-9viyc-x 8bi1d )a eactions. A diagram outlining t 58-1sc)ytdv4wx bdi9pa awi- he Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown bd73uqii +di6 in black andb3 d6 i+ui7iqd 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 shown z.*w alg i034pk8 m,7uvcindzbelo8p0i,kl 7gc34 i nm*wvdu z.zaw? Letters represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enxur 5r+( wt;tbzyme-catalysed reactio5+ uxb;tt(wrrns?

  Which of the followin3:y )-xchg ucp:k- tgng correctly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and mu2c b:hu quo-2 5kyz9valtiple enq: kb2vu o25 9zc-ahyuzymes.

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

  Which of the following best describes the inhibb*t qoca0eztoo5x4+ bl b;v8)itor in the image below?

  Which of the following statements are true regarding regulation by e.r0s cmlr wlu: -hzc3 l,z28jmnd-product inhibi mh sc0wr-lzmlz3uc, 8l.j2:rtion?
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 stk8wj1r04ivbb 8k;cf nructure in black i8r4vi 8fc0kw n jb1b;ks 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 on the xvwyv((/d :i0fe an,l activia((eixwlv dn0:/f ,yvty of the 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 stath v: kz8m(yief8o1*r 7i utd1sements describes how enzymes interact with substrates to catalyze reactionsy dm8fv8sr *e:z(t17uik1hio?
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 catalys oajlm7s uv.5)m96 vwfed reactions can be measured.

  How does denaturation change the properties of an:5 xy teq4wj9xllm+5e enzyme?

  Enzymes play a role in catalysing reactions. Which of the fol 9.e4b3 hhxseq*34 poyyefc t)lowing statements are true? e9f4bohyy 34tp) cxh* q3e.es
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 thye8r 6ozlu1crine30vmbv(++cg i 0* sat separates mammals or endotherms from ectotherms that have fluctuating body temperatuy lc1 c n(ir+iu*0ve8 gbmo6+r3v0zesres?

  A metabolic pathway that converts threonine to tjsa-t q1:f j)qokgfprb3++ 8dhe end-product isoleucine consists of five reactions. Threonine is converted to various intermediate rd)jf f: bs+k3+-jqt op81qag 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 tv+ +u 7tt3q vn(a,fnpv.ou8ton the rate of an enzymatic reaction. What is occurring during the phase labelled secti7pq.tv ou++n a8t,tv tuv( 3nfon X in the graph?

  An experiment tests the effemt pa),)myt jtpzz- umd*f*q90q 0e;u ct of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent vy0a ,q*0)tdzutmp* jmu) 9z-tfmqe ;pariables in this experiment?

  The diagram shows the pathway that czjovk3rm+p u7k/h9 1d/ ql5tvonverts 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 activity was compare4g/tl9y1: vnrrl y.dhd with that of a l: gvr.yhl/dr49ytn1 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. Which of the followi+p-uqdar da; u5wad, v122hfnng is the best way to keep enzymes ac hrdf,12+2udaaud v q;5aw p-ntive for a longer period of time?

  Which of the following describes some t b7 a c7wkw2,hahga/9jypes of extracellular enzymes?

  The enzyme pepsin hydrolyses protei1 jws 1ohh.8dons to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concent 1w8dh1s jhoo.ration 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 3z* qld.y:kotrate of reaction of an enzyme with increasing substrate concentration. Similar concenk3 dqz:o*t ly.trations of chemicals A, B, C and 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 enf -lo2 fg0wfdfgb(gju5 3r f mvkkq71ly:*p9-zyme 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-p5f ug2f *j:vb7dlkf mo( 0gf 9lwr-1gyfk3q 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 enzym8sb 6w8tx3dcshj8t8 fe HMG- CoA reductase can lower the production of cholestedbjx 8s w68fcsth83t8rol.


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 ixwrju45pc 4r gb3p7 p0nvolved 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 investigatinocl dq ft*2l(.g metabolic reactions in the classroom and were given an experiment whf* t 2l(.colqdich 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 effeehh f5ub -. t-gk(w/9nqd;iizct of increasing temperature on the efficiency of lactase activity is tested..fi(hdb qwi-n9ut k;z5 e/-gh Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a spe9,3wc381c 8rdztrn l4dwcq 8k;yca a pcific lactase (Bg10), analysing the effect of pH, temperature and glucose cowr4yp,98dw c3c;a3kn d q88zl 1trc acncentration, 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 need to find new drugs for treating patients with malario 1ovg37zv bz1a. Des z3bo1v7zog1vcribe how 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 re++u/3i p jeiytactii3 y+ epuj+it/on.
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 wa: o wr )p2(,drlh6xj2oyd: msynthesized through metabolic reactions. Which type(s) of metabolic rxd :w)pw(o2,yj2 lrd:m 6hao reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different wxxcak.n x( m ate-c;w-nt 75-mays the rate of enzyme catalyzed reactions can be measuectnmm(a7 ac.n;-5 w x -txxk-red.
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, dnkrco;b.x 5;8(ymi;xovir5z ux8i chemical reactions, given one example of each type ofx8oob xci 5d;i(.inkv,xu8r5; z;rmy 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.