Which of the following macromolecules descrc9ih9 oqryl-4 ibe a typical enzyme?

  What type of reaction is photosynthesi/ph mfc4sh:2)hz jbfu3/h li 2s?

  What is the substrate fo c1 0z4t45v;zcqr,s1 z ed c*wgkcc *uj)rgmq0r the enzyme lactase?

  Which of the following stages of cellu88t pae;aydb *nma,.k lar respiration takes place in the cytoplas;,da k*tp8aan8e. by mm?

  Which of the following would not be useful in determininaqaa8 /t8dw)d g the rate of an enzyme-wqda8a8a d t)/catalyzed reaction?

  Which of the following processes may be described as catabolism?(z2ql4 h+ fnzb

  Which of the following stateme1;pid wsl7( dz- f6udknts is best depicted by the figure below?

  Which statement about enzymes is not true:+5 x*y4ueu z/inwghr?

  Which of the following graphs best illust 9 00fwu2 ts1cxe,d-i;nmo z7ntcdm3 irates the relationship between temperature and the activity of enzymesc2scin,7fio0 u d xmt;1d309-nemw tz such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affe0o1 do) :rj k:iezlr4*teaz*9sqh2f vct enzyme activity.zoh01*q*:2 rfsa l )vz4r9dke ojit:e
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series oc3r, -a)onkehf enzyme catalysed reactions. A diagram outlining 3e,)ac nkr-o hthe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. Thei,8ip9fzf:lp:ge a5drh u0v ) substrate is shown in black and is bound 89ae f0rp) v5g f::piui,zdlhto 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.+5yc5xbk-1 r6p6p/vmk kiqzeafod8bo k0 1n the enzyme catalysed metabolic pathways shown below? Letters represent various products -bkb86 xf+1 5 krn6 oqpcz/edkak0moy1v5pi. of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed y82 (4r 63zlb zt. rnf7xcj8bd 8n)ns+xueabrreactions?r)nxf6yb7bc 8zze a 8. (n4+sjrrdxt8b2lu3n

  Which of the following correctly describesf7 5go,mg xmu)tcg72r photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and multipfa216o 8d vxlf0-ci fole c1lo2f0doa fxf i-6 v8enzymes.

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

  Which of the following best describes the inhibitor )qqj6ec9pe. 2 (bp txcin the image below?

  Which of the following statements are wej(ric-k-a t:t . s.xtrue regarding regulation by end-product inhibi. t-t(cjae:ks-. xwrition?
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 structur9p 9 q;h*ip7zj q+:) mqrdftvoe of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the r)9*d+qp qqih;j p79mv:t zfo active site.

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

The equipment below can be used to study7hf9n4 3a0a0klpxro x) j8dr5 l:gevl the effect of temperature on the activity of the e4 rxon5p ) lhx0k 9aj3g 0erv:all87dfnzyme 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 statementsdk 0foi(5/fv-p p1mns describes how enzymes interact with substrates to catalyze rk 1s-v0pid5fnf om( /peactions?
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 v )mgy2/g9 i(iqck,s(pw 6fef catalysed reactions can be measured.

  How does denaturation change the properties of an enzy( s gp(:(1xovv7*to uxnl 8hpume?

  Enzymes play a role in catalysi ;tzgy 2sm(6cmng reactions. Which of the following statements ar(ct2z6 g ms;mye 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 ejc )xo0i 7hj)dndotherms from ectotherms that have fluctuating body temperaturei)j )cjh7d ox0s?

  A metabolic pathway that converts /9a z6 wx+fkin34j .gws*qqzbthreonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzf*jzwxi3 / 4. aw9qkn6zg+sbq 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 rak7; t er txi;+tbf9tr7 ap,(y(q;iuaj bip5)qte of an enzymatic reaction. What is occurring during the q;(7ab;f 59t+xty;,)k rpqaib t urpiit7ej(phase labelled section X in the graph?

  An experiment tests the effeg3cg c;yzkgb cs5uzh():xk 9,c :q /prct of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent varia; y9rgp kkzxc/c:z:,b )gh3(c u 5qcsgbles in this experiment?

  The diagram shows the pathws(s/g-jr drbg*1suo t01n9 dway that converts 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 co;d61 xv r 1sn:a)ft-ip2tzgjrmpared with that of a free enzyme in solution. The graph shows the relative enzyme actan 2sjtg-zix pv;1:r1 rft6d)ivity (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. Whrc6zom rkk kr63++i- iich of the following is the best way to keep enzymes activekrrir+c k6mz- +oi6k3 for a longer period of time?

  Which of the following desbj5sm lwelio ,bqvux74(; o 1*cribes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A llfpxzy.:xm w05( og3study was carried out to determine the effect of incrpw x(.z3ll xm 0ofy5:geasing substrate concentration 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 rate of reaction jobsl crf;4lnp.l(, ; of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the ac(c, jlpr nl;b;.ol s4ftivity 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 a turnip bbozv+3xq*ao aa5 q -:blsx;, 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 aasz,-l+5b 3;qxxo: bqvo ab *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 w3eock26 k4 lyto the enzyme HMG- CoA reductase can lower the prod3l 2k6 e4okwycuction 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 denaturation qoaz-g/t9e/4 )w rjtm?
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 metabolic reactions in thm/:w kyte8;/gz cc.oqe classroom and were given an experiment whico;mc eyg8.z wk qc//t:h 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 temperatur5ifhb6nn 9om z*pv /):dspqw: 3pkv ,be on the efficiency of lactase activity is tested. Which is anpk n)v/9 bp,q3mz p6 os:5fhb i:vw*nd appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a spemt 7fe2i*6zffcific lactase (Bg10), analysing the effect of pH, temperaf6i7m t2z*f feture and glucose concentration, 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 fiofn9 y/y+f5 isog+ sn,nd new drugs for treating patients with malaria. Describe how anti-si+o,y/of n 9y fsgn5+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 t tqe8(glz 6(0vki ,brof an enzyme affects the rate of reacttgz,( rlev iqb6 k(80tion.
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 synthesiz/swdmgwz q :y52aqcf4fc w(6- kr9d h2ed through metabolic reactions. Which type(s) of metabolic reactions awk-5/2d wa2:hq(y w9g c6m4drcfqzsfre condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzcf1jwl;f/ ab: yme catalyzed reactions can be measured. b/acfj1;flw :
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 extracelludg2c bdg*d .b4 3vjin1lar chemical reactions, given one examd.bdb1i4v3jg*ncgd 2 ple 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.