Which of the following macromolecu1g+l oow p:k3/i db.u)1o9yqunvef1g 1u) iz qles describe a typical enzyme?

  What type of reactio 8wwls86gre:0 qul/es/-u wrj n is photosynthesis?

  What is the substrate for the : ha3b9i/epn umzl /o.enzyme lactase?

  Which of the following stag:p; nv)wl l2akes of cellular respiration takes place in the cytoplapw ;vl:2 )klnasm?

  Which of the following would not be useful in determining the rate of an enzy.g;fyi*xq1 pr j89nond.cm yn-y1j u:me-catalyzed n1gyy:8jcip r.xn-o*umjy.n 9fd;q1 reaction?

  Which of the following processes may be described as chna w+db*p.r wrj u7ro:2jeh(0us*l)atabolism?

  Which of the following statements is bylm7hc ls sjxyuck6 j1t-j* kmc/+13*est depicted by the figure below?

  Which statement about enzymes is tl65uz+ nncu8g uf16eap :a2anot true?

  Which of the followi:pnmq9fm4.kq t 5 lh5yng graphs best illustrates the relationship between temperature and the activity of enz mq5.lnfpqk hy5mt49:ymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect eno +o3p4bhjei nn);p +fzyme ac +fo;3pejhop i +)bn4ntivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a seri fu 7;g+my8d+cahrke.es of enzyme catalysed reactions. A diagram outlining the Calvin cycle is shown belomg8c7yer +u .dk+fh;aw.

The image below shows the catalytic site of an enzyme. The serwas;8bt e3quu93 t 0ubstrate is shown in black and is bound to the acet3aeub8;9s0q3 w rut tive 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 enzyme catalysed metablb h6o;fd1p1 iruh +g *fcoi-tfr:*-kolic pathways shown below? Letters chpl*6o: i-t -krrob;fg 1 u*dh+ffi1represent various products of individual reactions.

  Which of the following describes the role of inhibitors in erj 5hv*k.cov/nzyme-catalysed reactiokcr/hvo.v*j5 ns?

  Which of the following correpae:4 9jl;7w0dg4h*h y57 bhx.njlwhq zs7gyctly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involvinvq (2svy3/k(2sbrjznbtxs r 78 g2d )kg multiple steps and multiple enzymes.g(ys 2k /d brbq s7t8)n(v2sz 32jxrvk

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

  Which of the following best describes the inhibitor in the imf gdo5d-m8ve4i y7u* cage below?

  Which of the following statn)vjvbmijf m*g/ z:- 5ements are true regarding regulation by end-product inhibition?nv/j mj v *gm-5:)zibf
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 strucdnfz. ,tvz hf:e,mo31c. 2 iiuture of the lysozyme enzyme. The darkened structure in black is the substrate vi,,m..zh3dfz f1i2t :necu o 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 temperatuoset j8o+i+/xb4-m n ure on the activity of the enzyme am+io +uboje/x t8s-n4mylase.



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 statementsm-xf mk,o; 24 j8md 8o:fo9 bvnkwi7zl describes how enzymes interact with substrates to mvo2km kb,fw df 8;8n9l47joxmzi:o-catalyze 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 can be measurenr6ex k s7o de6k6*.sid.

  How does denaturationvvi+2ft sk r1, change the properties of an enzyme?

  Enzymes play a role in catalysing reacwb,x4ix y9)n8 2 jdqlctions. Which of the following statements awj2 q)8ln,94i xdycxbre 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 o57bf56iqoevd lt4-,lwl l g)v9 h j(hmammals or endotherms from ectotherms that have fluctuating bodhg-5 t 4l h7jfv)(lqlvdbow e 95l,6ioy temperatures?

  A metabolic pathway that converts threonineh:wp((amz l xff4,9lg(k tuitcsu:)9 to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by difklhlcmaf9tp4 tg uwi(uxz,9:) s :((f ferent 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 ejgy)9rfs 0hh/; +fye tnzymatic reaction. What is occurring during the phase labelled sectey/hhsjt+ f0) ; ryg9fion X in the graph?

  An experiment tests the effehrzwyx(c3 3f7w- ,b cict of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables i (rfy , 3c7-bichwxzw3n this experiment?

  The diagram shows the path(y x5(e8urxycy4kxp(slcs5 0 way 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 cbj3p) 4b j1olxompared with that of a free enzyme in solution. The graph shows the relative enzyme activity (yj xlo31bp )bj4-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. Wo f1swsg4,-yd i m.qu):d ch*khich of the following is the best way to keep enzymes active for)i 4fmgch -,s y.s*owdd:qk1u a longer period of time?

  Which of the following describes some types of extracellular enzym6w f hg uudy.x9i/+-qses?

  The enzyme pepsin hydrolyses proteins to releaswg pqmt; 6l.6ddz d*0ve peptides in the stomach. A study was carried out to determine the effect of inc.mz; qd6p lw*6d0gdvt reasing 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 enzyme with increa 65sxmf8go( vasing substrate concentration. Similar concentrations of chemicals A, B, C and mf6g 8ax (5svoD 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 enzycroqmftrg+q. n e/1*7me activity, a student 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 homogenreqt .m+/c7 qf 1*rognate 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)7dlkft::fv t . Inhibitors to the enzyme HMG- CoA reductase can lower the produ )d fvk7tt::flction 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 denaturagg9 2)36rdtu)0e6af vf zw zxytion?
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 metaboli*op(jqxbq q7pdaqd5 q,g0: 6 yc reactions in the classroom and were given an experiment which demon dd*p (7bj xo06aq5g:qpqy,qq strated 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 wjshm+-bca i6ky,q* 63 bqh.x effect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this q- .k+ 36h* a6bwxm,bciqshy jexperiment?

  A study has been conducted on the acb 1xa 41iu(:adxyekrm u.p+c -tivity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial1i -d :m.axb4yp( 1+uk ucaerx 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 continuou;o :qfijqh+.nxk 2, mss need to find new drugs for treating patients with malaria. Describe how anti-malarial drugs a. fkh: ojx+,is 2;nmqqre 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 affects the rate o pcpkovt c 5+ z1/g;chj10no-if reacvkcp j 0+cto51z 1c/ pghoni-;tion.
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 reactiodpzr ci*lo3(f2flu. /ns. Which t3*f pi/dz (ulof.rc2 lype(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed readd q/j:nm/j*dctions can be measu/jdq*:dd/nm jred.
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 chvz+.;osa p(w oemical reactions, given one exazpo+ ovs(a w;.mple 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.