Which of the following macromolecules describe a typical enzym34 wyzcf brgm*z1j3ky*,tv i0e?

  What type of reaction is photosynthesi) qyj3g)dn(j ns?

  What is the substrate forawd;np+ mo00 a the enzyme lactase?

  Which of the following stages of cellular respiration takes plac3v,hq fnmv ,;re in the cytoplasvf;3n,, rvq hmm?

  Which of the following would not be uqiho3))gl q3 pseful in determining the rate of an enzyme-catalyzedgo)) ih33q qpl reaction?

  Which of the following processes may be descri 9 t0zu3g4:sloq7 tocebed as catabolism?

  Which of the following statements is best depicted by the-fc(.icb7z. gg)obz wdfll s/x) d59d figure below?

  Which statement about enzymes is not true?)h:6h2 uf0pykt +:6ymlf nxou

  Which of the following graphs best illustrates the relationship between temperat su,eyqwnbyig2zmk7l;,ar43 (dcv) -ure and the activity of enzymes such as lipaseg7ykw 4 -mls qr)zv2 yd(e ua,3;inb,c?

1.Sketch a graph to show how increasing concentratiod 4r,fdruqp /0v.v xp9ns of substrate affect enzyme 9d0 rvp4.rdvfp,uq /xactivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a serie+e0 +qa.mruyus of enzyme catalysed reactions. A diagram outlining the Calvin cycle is shown beuyq0 +mur+ae. low.

The image below shows the catalytic site of an enzyme. The substratedvr/ *uyvb jm ( lp7r.l5 i9pi+gf7t5u is shown in black and is bound to the active sitel pvuriyu 5tm *bg9p f7(jv+/id5.lr7.





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 sho.f 26tsv-tczwgb h ik17lfb,-wn below? Letterstbc hz2gktv s,bl.-6-7ff i1w represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catagidhon024;kj or. j l;lysed reactions?d;oorh4.g2; kijn j0l

  Which of the following correctly describes photosynthesid-4l royrk2 i9s or respiration?

Many enzymatic reactionss, mbo)7 +hrxu happen as pathways involving multiple steps and multiple enzymebh,+r)xms7ou s.

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

  Which of the following best describes the inhibitor :ex pdc;i ev8ggn,x(/b6ob -y in the image below?

  Which of the following statements are true regarding regulation by end-produ ou9.)o.-afcz-mcr dgct in -rco9)afocd..z - gmuhibition?
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 th)v(1(: dxegn4/c glq hf/jklo e structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at tohf /dl(qg14 g enj( kc)lv:/xhe active site.

Which of the following characterizes the active site of an enzyme?

The equipment below can be used to study thq xm:w80s72 meirrr)ie effect of temperature on the activity of the enzw0xrs2rmi)q:re m 8i7 yme 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 substrt * fyw14 +wnae2htn,dates to catalwafdywh,2 nnt4+1e*t yze 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 cata; mypngaa4q :wj0 3+uulysed reactions can be measured.

  How does denaturation change the properties of an en5b8a ig3lbrkan.5mr ) *w .aruzyme?

  Enzymes play a role in catalysing reactions. Which of the following s:57jlgmvz3kz tatements are true?jgz klvm5:z73
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 or endotherms from ectothermbe lu -vfgq3m(r: q4)tk.5jfls that have fluctuatijbq :. tmkv34f-ufl5lrq( ge) ng body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine consisjvn5k,95kk/p n 4rccsts of five reactions. Threonine is converted to various intermediate products sequentially by different enzk/j5np vn,k4c9rcsk 5 ymes 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 the rate ofm,2y u9y 2wqvo(a+ dc7a i+uve,wn/vg an enzymatic reaction. What is occurring during the phase labelled section X in the grwc7y9eyd(g,uu2qaovn2 a+/,w +m vvi aph?

  An experiment tests the effect onbpd k96cs*d9/kr u* nf changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables9 kd/r*b uc6pds*nnk9 in this experiment?

  The diagram shows the pathway that converts threoninee x ijrx-qu.2z3w-3z4+ pyj nwrd6*ye 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 mat2 *7qiea(4 5yde joojbrix and its activity was compared with * eb7q y4ado2i(j5je othat of a 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 followiam -lq0 ,nfq;:l x4ijsng is the best way to keep enzymes act-ql,;i: m4 s0ajxl nqfive for a longer period of time?

  Which of the following describes some typesm8y/,i hytnq3 2 x(fee of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptidescrsj v5p 9pq40 in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperats9vcpp4 r q0j5ure 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 substraqp(-qx fc.i z*te concentra.*p-x(qqz icftion. 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. 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 activity, a student cut alwd/s1 tni:9l turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 5w/: 9ilsltn1d0 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 shb8zzg w27x 2ob -m.tg9uhykqzgr )w*9own below. Inhibitors to the enzyme HMG- CoA reductase can lowerz7g)r9w g.* oygk 8b 9-z2huzqb2mx wt 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 arqwkd)-oc6g m,cx0 fi 4cj xj/+e involved 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 investwwgt52z;.*l f um/xbaigating metabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a ca*ugbw/z;xlw tm 5fa 2.tabolic 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 effectfg1 . u4 o7yel-i:ugxh of increasing temperature on the efficiency of lactase activity is tested. Which is aniygg ufh:u 1.-74lex o appropriate dependent variable for this experiment?

  A study has been condu9an d rq wxgi9hxexs7x.7+2v 6cted 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 lac. hix6 x x99nwqrd77 avexg+s2tose-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 wirbo;vh9 y(+jhth malaria. Describe how anti-malarial dyh;+9(v o brhjrugs 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 concentratio(g w,yh1 5gsxrn of an enzyme affects the rate of reactgg (hs5xr1 yw,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 synthesizep4ip22x:j y0x xc2yg qd through metabolic reactions. Which type(s) of metgx:c4pyx0jiy qp2 x22 abolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzedeznd *mgoz(y3 f-u ;3y ah,ra7 reactions can be measu(a -yf3zna;3mrozy7u*d hg,ered.
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 reactikvkbt)(+ork s -x1z e*cu 5e8ions, given one example otv uk k-biscxke1o)ze*8( 5r+f 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.