Which of the following macrupfr d/://ar6qjtv .homolecules describe a typical enzyme?

  What type of reaction is phmweltmo55 :6l75mmgj otosynthesis?

  What is the substrate for the enzyme lackbhx,xml:p5;thm) (.4:ba u:w jw5 rll eb6 dmtase?

  Which of the following stages of cellular respiraokbj6;4(v et qd2j2rfmzf1a4 tion takes place in the cytoplasm? m(41 4fraezoqtdk 22vb 6f;jj

  Which of the following would s-//qybpoik4tlvk:ca3f7y :r- x u 9wnot be useful in determining the rate of an enzyme-cat xotq 7/43ucfp- v/:yklria:-k sy w9balyzed reaction?

  Which of the following processduw-9a:mxsc( l w z36ride 2k*es may be described as catabolism?

  Which of the following statements is best depidf8achdw6)n4/z 6 v3ssviw pr + 0ae7xcted by the figure below?

  Which statement about (3:wkc y8v6i ;nuxn pdenzymes is not true?

  Which of the following graphs best illustrates the relationship between j66cr8 zjn+oo temperature and the activity of enzymes6ocj+n8zrj o 6 such as lipase?

1.Sketch a graph to show how increasikj/rr1gy4ci+f x.8r *th1lh qng concentrations of substrate affect enzyme activity.i4gq+h rtl8x1 .1hkjrcfy/*r
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactions. A diagrar4 o1r3ny 07begrx;qrm outlining 3xnrry er;q 7r0g41 obthe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate ij8 le8x vpu:mk78bg1g h6e0cz s shown in black and is bound to the active sje 1 8uk88xg :cg6v7ephmzl0bite.





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 acqv(-a;jv3 eac 5o4ecatalysed metabolic pathways shown below? Letters represent various products of individual reacaaea43- ;j cqecv5(votions.

  Which of the following describes the role of idsk n .(ux3t0cnhibitors in enzyme-catalysed reac(ncst.0 3xdku tions?

  Which of the following 1udh vf.*v ghl yo5:2ocorrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as paoo va (r yl1*)yio;v:sthways involving multiple steps and multipl ) yovroa i:y1v*slo;(e enzymes.

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

  Which of the following best describes the inhibitor in the, xa)+yffm x*w image below?

  Which of the following stateme.p g5,v ji ovsq/vh32bnts are true regarding regulation by end-product inhibitipbjo2,vsq i3h/. vvg5on?
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 lysozymed3a*:e q0e sls enzyme. The darkened structure in black is the subesq:s ed0l3a* strate 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 ofpt(y1b/ vna1-f0jo z s temperature on the activity of the enzyme z j/n0p(11tasv -byofamylase.



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 o;;(kc xf(wr3x/ 1s4 ijgdpfbwith substrates to catalyze reactionrwi sokfp ;c/(fj 1xx(3d4 bg;s?
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 can becuj52wnnpjlwo 5 449d measured.

  How does denaturation change the prop x73:ifx8tnva erties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of79nz0rh 2)mw 5v4d v9ot s)yzjibch6 p the following statements azo92v)mv) pdh4 biws yzj0 t5c 9rhn76re 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 maw(425cw xk .. b; j.tkaoj+ajgaw ivx(mmals or endotherms from ectotherms that have fluctuating bodyaj bkww x.g+. xj vitaw24.kaj;5o(c( temperatures?

  A metabolic pathway that converts threonine to the en(po mpjfrx) *ooj(o 37d-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by diff j(pfmoj7xp(3o*o )ro erent 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 on the rate of an enzymatic *fi* yfz nd2 *1 sbcmx.dq;1vwreaction. What is occurring during the phase labelled section X in the f*1zw*fy 21s dni *b.qmcxv;dgraph?

  An experiment tests the effect opflf ,68(codn f changing substrate concentration on an enzymatic reaction. What co (fn86,fdclp ould be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isole/ejb10z1v f4;qh m uavucine.



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 ac -vamfe(tsn,:rl7h *)fu lb*3usr/hrtivity was compared with tmvn -rlb7elr*/at s)s3:ffh h r*(uu,hat 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;2ym, ffnqq:68ke m zh9bfwd+ denatured. Which of the following is the best way to keep enzymes active for a longer period ofn6; z 8qfmfk9,2m:fhwby + edq time?

  Which of the following de2d:.9eizto x4b vgt6hscribes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptide+;yyqt-hns -u s in the stomach. A study;s-yqht-+ nuy was carried out to determine the effect of increasing 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 of an e01 cl/ n0p,rpsk6 kfwv,bk v3 m,q1vq/8vycrknzyme with increasing substrate concentration. 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 marfblvmp6 rn0 /s vkwqkvq183v ,,0,k p1ykr/ccked 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 root into small cub7e/ic;+i:4p pduli pgu zf: 8bes. 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 extract was stored in a ugp7i ipf+d;cu/zi 4be:8 lp: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 sh0hqepb ;c.njc-w8m( c :(spo bown below. Inhibitors to the enzyme HMG- CoA reductase can lower the prod.0pc pwb;8c msnceh:(qob -(juction 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 denaturatwmj6 t8ofi.b7 xc 8q4aion?
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 reactionp0bzvtwkp uvf+,w)f* gt2 3v 1s in the classroom and were given an experiment which demonstrated the effect of temperature on a catab3f* wv 2pk10, ptf)+ubvtvgwzolic 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 efmrru9 :g44-,pn mwndxu8 t d;..rm nrjfect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this experiment p ;j:9rr tu 8.4m,mnr4r-gdnmwd.unx?

  A study has been conducted on the activity of a specific lactase (Bg10), an/:fbshxozakm)+f08 z x b1us(alysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commer/h s bx8mu fo: kx1a0b)fs+z(zcial 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 cxxc7 bg24 upugoo5 /1atn -q+find new drugs for treating patients with malaria. Describe how anti-malariaa7p/ gx-c 1cgn5qut +4oou2xbl 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 enzy6vvtgys o*z0:me affects the rate of reaction.zs6*v gtv:yo0
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 through metabolic reaqf jl1.hxe+y5cu4 -u nctions. Which type(s) of metabolic reactions are cocu4 1un-xl 5j qe.f+yhndensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different m y k7os6o2xu+ways the rate of enzyme catalyzed reactions can be measured. 6 o kumx2+7yso
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 intracell *wq1im15y isfular and extracellular chemical reactions, given one 5im1yiqsf* w1example 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.