Which of the following macromolecules describe a typicaf o(wmd2rtxp-,w 2paw+ct *9c.wn k9x l enzyme?

  What type of reaction is photosynthe /ohujh,y6 .wqsis?

  What is the substrate for the enzyme lactasfql9 -(u5l n yewliu;,e?

  Which of the following stages of cellular respiration t kokj(*87ac zzakes place in the cytopla*oj k a8(cz7zksm?

  Which of the following wouldqz73 vqbhv89rib,mn/qnbf5j: 1s f + k not be useful in determining the rate of an enzyme-catalyzed reacti q8 +qzmnfj r/ q:f31ni9b,k hbs75bvvon?

  Which of the following processes may be describedh5 ylh)isu,rv)lq dn5 p:*p c6 as catabolism?

  Which of the following statements is best depicted by twdbgty s epp..0/ lo8-he figure below?

  Which statement about enzymes is noz70*u*nn+jazixu r+ gcespf xn7h(3(t true?

  Which of the following graphs best illustraefptxcf41u) fq p56, ztes the relationship between temperature and the activity of enzymes suc1)p,epfufz 5 xqt6f4ch as lipase?

1.Sketch a graph to show how increasing cob2 r1; ..q(wu 5by8ihjxnlbqw ncentrations of substrate affect enzyme acti(h.r;ji1qbl 5w8. xnb wyuqb2vity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of en:d 1 teruyt7*kc 39t.hp4urcw zyme catalysed reactions. A diagram outlining the Calvin cycle is se4u ttrd c1 pctwy9rh:k*.u73hown below.

The image below shows the catalytic site of an enzyme. The po) tcl.rzprgns0t+7:ka+i9 substrate is shown in black and is bound to th cp.+pia: szkgrnlt +)709ot re 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 or0cgbazssn 4im5+ 6*df the enzyme catalysed metabolic pathways shown below? Letters represent various products of indsnsc6r 5 azg+ *i40mbdividual reactions.

  Which of the following describes the role of it(+met(xznfn ;02b sgnhibitors in enzyme-catalysed react+zxgbf(;se 2m( 0tt nnions?

  Which of the followin e oby h/bvdq6dia :n/4gq6;j.g correctly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple s:e : +cwkdrg3wgz0 lr(teps and multiple enzymes.3rd0 g +(c:rz:wgkw el

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 ko k0w3j lu2sbh(mx.8 agmn1 *below?

  Which of the following sugp6r3+a6twevyo (46q xz:cs tatements are true regarding regulation by end-product i66o x:p zy4aq3wgrs+(u tve6 cnhibition?
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 enzym8 /kj c gucp+yel7m-e9e. The darkened structure in black is the supy+8g uj e cl7-c/mk9ebstrate 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 te;qh);me/ *kntjlwu4zmperature on the activity of the enzyme amylase. l jm)4/qt*z h; wnu;ek



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 - b,1c9 mnouu1xo3qmqdescribes how enzymes interact with substrates to cat19 ob cmu,m1 -uqnx3qoalyze 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 c o8 kh7b,hvhq p2cjk(jv4e q x+i2i2s0an be measured.

  How does denaturation change the propertar9qzm. yp5xhbl-o 7(8c h.w pies of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statementsw/qjuhu4*w 4+zsmd 6s are t/ujd hu sq6+s*4 zm4wwrue?
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 ectothermsh9zs 0.xa x2l5i7kc i,h8r trh that have fril0 z95,hhh7.crxk s atix82 luctuating body temperatures?

  A metabolic pathway that con6p -naui0hx iqf w sjx+f234,yverts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by +06a pfxih4n- uqx,3fysw2j i 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 of an enzymati90 oqt03 ,xpcb.wct brc reaction. What is occurring during the phasc pxt 0b.r ,w0qco39tbe labelled section X in the graph?

  An experiment tests the effect bl*1 p 687krdbxc)wkzof changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in thb zkp8cw *1klr67bd)xis experiment?

  The diagram shows the pathway that converts threonine to isouk/hyl+yk412lx2kdy1v 5 wojleucine.



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 comparux z-osb7q/6uxar w)) ed with that of a free euu-7ba x/qwo6zr)x s) nzyme 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 fdfmy94oa2o 1tq 63 udwollowing is the best way to keep enzymes active fyowa3d4 t2q 9d1ofu6m or a longer period of time?

  Which of the followi)sj: bbojo. *mng describes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the lub;,2tlu,c)b 0l(vjg *c npku3y. hustomach. A study was carried out to determine the effect of increasing substrate concentrab0kul(uuy ;bgv ,h)3pn2lc*,ut cjl.tion 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 tuw3n38zqs+kn qk9j 4uhe rate of reaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were a 3 uz n4j9nqs3w+u8kkqdded 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 cutk jhzghn*;qb w -;(is; a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender tohjs (bz ;kihwg;q n;*- 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 bei4a *x*stx ;aulow. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholua4t;asi x** xesterol.


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 involvezf ;0eb,w4q :n* yf3ms; g,in,cswtxod 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 metabolic reactions in the classroom and weo*90z6 vglfubjy mv8z 6l3l1vre given an experiment which demonstrated the effect of temperml0yg1l8 39 bzuzv jvlo6v6 f*ature 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 increasibcsqgu :vhryr.0 /k-. ng temperature on the efficiency of lactase activity is tested. Which is an approprigq0.hs/v - .uyrrc kb:ate dependent variable for this experiment?

  A study has been conducted on the activ,v5 m (b)vvar jb a-n*bmfs80xity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may -) mbf8v vvjb*5nb smxara,(0potentially 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 3w/0/wn7gg en+im h;iv 2j(o odjs1xjneed to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discov/moihj xjjg2n30dev7osg +(w;/ i1nwered 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 thez1/x;tr*gg eh concentration of an enzyme affects the rate of reaction.gztrgex h1 *;/
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 ihokauz8 1a0r+, aejx:i +mb, synthesized through metabolic reactions. Which type(s) of metabolic reactions are condmji8a1iak e0uzx,ro ,:ha+ + bensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differjvj6+.i wszo9 ent ways the rate of enzyme catalyzed reactions can be measuro9jwsvj .z +i6ed.
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 extracellula1 zpc/ j-2l adubf)7l9em3p qwr chemical reactions, given one exm27b)pl- c dqf ewza1/ pl93ujample 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.