Which of the following macromolecules describe a typical rhw(f/ hg w 0i-+b;cx ;s;mmxgenzyme?

  What type of reaction a aro/y2zfb9 m*5uj)*uu9auris photosynthesis?

  What is the substrate for the enzyme lab;)avu mak7s lw +-xtnd:1lb 8ctase?

  Which of the following stages of cellular respiration tae*x6( sol6bl j p;(6a7wzne)m.0y+lv ts nzbokes place in the cytoplasm? yz;tn0lev6 e +.7oxll (*6 )bo6 jssw(azmbpn

  Which of the following would not be useful in determininge.f+ bodnz(pb-q3b p6dspt+ 0 the rate of an enzyme-catab60b pnpot pd fq3.+ e(bsz-d+lyzed reaction?

  Which of the following processes may be describ:x8 sgbef0vl5+xgt3, tglm k0 ed as catabolism?

  Which of the following statements is best depicted by cg1 c s(, ibwsj9 o fdg8r,4zpjv+j0s2the figure below?

  Which statement about enzymet a6c+j7mg 1:( t/w fmz1igkhds is not true?

  Which of the following graphs best illustrates thet4ejvrkzo)9c7w pq*f+ b)wl ) relationship between temperature and the activity of enzymt7)w*9vr)z+ec bqwo kf p4jl)es such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affekkr5 sk:g e1+pct enzyme activ 5kks+: r1epgkity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is t 1zxw .d)3go4yyul7, hk*kkla series of enzyme catalysed reactions. A diagram outlining the Calvin cyc,k)zh d.k w74ol t1g3l*uxkyy le is shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown i6*f v0ya; q 1+h1s08nqoej xwlwm 1rshn black arqs+1hhqamxyveow 11 ;06f w n0s8*lj nd 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 enzymet5* ic79zx/kqsdd l. iy/y j5r catalysed metabolic pathways shown below? Letters *qc j.5 d/r9lktysi/zd7i5 xy represent various products of individual reactions.

  Which of the followiyw w- 7y*kbl0qng describes the role of inhibitors in enzyme-catalysed reactwyl 7-w0yq*kb ions?

  Which of the following correctly describes photosynthesis or resvvk:0lel p-x3 piration?

Many enzymatic reactlk 7xng-)5wd8uqw l:aions happen as pathways involving multiple steps and multiple w ulqdn7x8klwa): 5g- enzymes.

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

  Which of the following best descrik b ox3h:bd/)nbes the inhibitor in the image below?

  Which of the following statements are vob9fw 2j 6yw,u6rkc4j i-v*x true regarding regulation by end-product inhibito wb9iu2f *46jw,v6j cvkr x-yion?
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 enzymewk66fj oj7b e4. The darkened struw76 bjk6f oje4cture 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 to stud 7(abkp 5z,rrry the effect of temperature on the activity of the enzyme amylase.p(rzk ,r5b7ar



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 intc2 d98ijqqh-j eract with substrates to catad-jiqhc98q2 j lyze 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 reactions cajci0r / p8qxv5f2mox(n be measured.

  How does denaturation change the properties of an enzymeuu4* rf8w cm/;tes 1ylrnpko 70tt-x /?

  Enzymes play a role in catalysing reactions. Which of the followi:bd8wsk7+cru ng statements ard7brs:u+kw8c e 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 or endotherms from ecfo7k+h 7z3hi7ori 7autotherms that have fluctuating body ti+ 7ohaou7hz37f7r k iemperatures?

  A metabolic pathway that conv2,j -y s+np.ia1qxq)nx; ucia erts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes bja,qxx-2snii.quy1 ) ;n a +pcefore 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 o uj -:1snofbi(n the rate of an enzymatic reaction. What is occurring during the phase labell(fjus:n1-boi ed section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enz pthi+4ou //9iyqyuxe4;agn/ ymatic reaction. What co/tqu/yn9 yxgei4a ipu 4;+/hould be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucinnmn5+ hqb8 t4lnap e77e.



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 compa6e:onnio a/+ured with that o/no i+en6ou:a f 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 following is the best way to )zdql--h*fp x keep enzymes active for a longer periqdz)f hpl*x--od of time?

  Which of the following describes some types of extracellular enzymet) ojiczgcwz01: nz6 :s?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. mzgbkc um5 ah6ls2./, A study was carried out to determine the effect of increasing substrate concentration onl.su2bz 5k, mm/hacg 6 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 rate of reaction of an enzyme with ihd (m52mq3xo m k m5rv0l5y9* /ryehkgncreasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the h yr2mdo5 gm*r( kk3hxm5v 5l9m/yq e0activity 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 studentd,:vp1* raayi 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 homogenate was filtered and the liquid extrac1,i r:pa da*yvt 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 enzct )i+ru ;,6hajmtmap5;clb/ yme HMG- CoA reductase can lower the productijt/u 5caia;,)hc;+m r 6tplb mon 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 followin 5,yh hq97ruzfg are 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 investigating metabol81 -aa(47i bbcoz szaae 3wzk;ic reactions in the classroom and were given an experiment whic3( o-ea14a;b7a az8czzs wikbh 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 temperature on the efficiency of1 w;d. x6qfa-er9iynw lactase activity is tested. Which is an appropriate depe9nr 1.6qywd-w;efxi a ndent variable for this experiment?

  A study has been conducted on thq v r ,slbl6-7dq q2(,wt9grkke 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 labr 7l,rqkqvqg,sk 9(t62- lw dctose-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 e.-ci dzo3syi6li22ndrugs for treating patients with malaria. Dizei-ys 22nldo 36 .ciescribe 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 affectsf5 p1grg7tatjvl9 w p97/to8n the rate of reactif wtgo71r/jap987t5ngp ltv9on.
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 throug5 siu68s5efb gh metabolic reactions. Which type(s) of metabolic reactions are condens565g8usf ib seation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different wayszx spxsay*d;*t5 v)9jn. 5nnp the rate of enzyme catalyzed reactions can be measuredd.anp j s 5xy*)p;t 9vzx5snn*.
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 extracekkr1k*g m..hq+ o zxe3llular chemical reactions, given one example of eachk.g +*ek mqkz1.oh3 rx 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.