Which of the following macr //rh rnzqd /j7ejn0;homolecules describe a typical enzyme?

  What type of reaction is p e.3 2yu 2oyyc+omyh9photosynthesis?

  What is the substrate for the enzyme lactavei1n)1*n3sneoqa q1x- vq.9tdu 4sp se?

  Which of the following stages of cellular respiration takes place in th lt,.dewc5s, bpxnq 3/qp* ie2e cytoplasm 25et/swx *3elp,,b n.piqqc d?

  Which of the following would not be useful in determinx7j f 5.fiz q(xyl- u,cfna55uing the rate of an enzyme-catalyzed 5(l .i 7qc f f5zny,x5fujau-xreaction?

  Which of the following processes may be described as catabol-:pi)ph wpu j00fj o.tism?

  Which of the following statements is best depicted by the figbwh: eza*w dwty )7*z7ure below?

  Which statement about enzym34 v ziu) ycm t:odmyzf.-ce(.es is not true?

  Which of the following graphs best illustrates the relationship bete3v*iv y h.0uuween temperature and u .3y ivvu0h*ethe activity of enzymes such as lipase?

1.Sketch a graph to show how increasing l3s2l,p3vb uedfn /w3jgb,m n7 6 fhk5concentrations of substrate affect enzymefd6,sl3j73uk/nng 3 e,hpf5 lwbb2m v activity.
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 di qcud.,20or acr4h 9dd5qgw,r agram outlining the Calvin cycle is shownaqoh,.c4 c2qrrd u0,rw5 d9g d below.

The image below shows the catnm9nil nh )4qmsa;8 ,zalytic site of an enzyme. The substrate is shown in black and 8smqnnlm h z)n;94,aiis 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 desc( jg 8;z m)lwwxn7m5wey04grwriptions of the enzyme catalysed metabolic pathways shown below? Letters represent vario 0x(r;5 z wg7mw8yewjnwlm4g)us products of individual reactions.

  Which of the following describes the role of1w-1 fq2w.dkkdxu: m y inhibitors in enzyme-catalysed reactions?xd1qmkkw:d1 y2w u f-.

  Which of the following correctly descr-pm8stvo8h ccg9y :gst; a:*/im /m dwibes photosynthesis or respiration?

Many enzymatic reactions happen as pathways ink,))val c.ll rvolving multiple steps and multiple enzymes. va, k).lc )llr

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

  Which of the following best describes t l16r-e qta4rc2evl q2he inhibitor in the image below?

  Which of the following statemenss5szpo-*r,n ts are true regarding regulation by end-product inhibition? ,sr n -pszs5o*
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 , ;dp7 x1rm ;ormhr8strm:g1sof the lysozyme enzyme. The darkened structure in black i81pmmhs; :;xt mo rgrdr,sr17s 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 sg/ 0.2 sztbvtytudy the effect of temperature on the activity of the enzyme amv0/gstbtyz .2 ylase.



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 stata :n(wt1ayp/ pb(.dsbements describes how enzymes interact with substrates to ad1awb n:pps. tby /((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 reactv2ek7 m3wsem*ctl.x (ions can be measured.

  How does denaturation zj8djjb2j65 pchange the properties of an enzyme?

  Enzymes play a role in catalysing reactionslqa ,a+2mskz u/l )k4j. Which of the following statements are trus+a /qa4kjll 2 ,mkzu)e?
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 ectothei) (fvj)x f5vdrms that have fluctuati fvxv( ))fdi5jng body temperatures?

  A metabolic pathway that converts threoni7qci*h0us6y r -xhg :pne to the end-product isoleucine consists of five reactions. Threonine is converted to variou u0 chgiyq:*7xrhs 6-ps intermediate products sequentially by different 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 increasik- 35 at:2cm w3i3srosrgac8zng pH on the rate of an enzymatic reaction. What is o2rz w5cmr: s8tgi33ka o-a3cs ccurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate c t;9n,jvr-n9*k8v uodzqy0kzoncentration on an enzymatic reaction. What-zunvtjqn*vok d k9,r z0 ;89y could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threon 4h//tw 1mvvwyw keyi -5hz6*f8hf,nvine to isoleucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was im4 /nc,e ksyo)3,lab qqmobilized on a matrix and its activity was compared with that of a free e ab,qlcn/4k e 3so)q,ynzyme 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 t8qo/2 ikuao6w)5thxc mu:mmly17. 3s wwxbu .o keep enzymes activxuoym5ac mtk8ihm2 wlow 7.b 6/qs.1w:3u ux)e for a longer period of time?

  Which of the following describes s7 ; 2q+;ssxsjmhjjahpy81 7 p+cl*b: zf,muobome types of extracellular enzymes?

  The enzyme pepsin hydrolyses py.pxl /zdi:cikn. t3p94hgd utx9g)1i;r. loroteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme aggxi y1rl)k3 hip..tzl9;d.tci p:dn/ 9x u4o ctivity 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 r lbjlldi(oh;hi e(r/2 d(;c,keaction of an enzyme 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 marked A coincides with the activity of the enzyme with nockil(id(; r;2hd ohle j,l(b/ 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 cubes.h ow.*72bxr6bu/tn oz They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. Twrh x .b67tu*o2nb/zohe 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 to the enzyme HMG-1yzx; 1 ff1v6sy 2tqod CoA reductase can lower the production of chodzf1t26ys;11 ovqxfy lesterol.


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 a3k- qfb.(1nbcex) *f;egth nlre 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 metabolic reactions xaabey,,5(wv 9hu wt0in the classroom and were given an experiment which demonstrated the effect of tem5w9e(y 0 atbuax,,hwvperature 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 b+-etw/mqqm- temperature on the efficiency of lactam+-tqewm -b q/se activity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activiy)n 059ekhsytxce2 ps6v, :vity of a specific lactase (Bg10), analysing the effe,):skiyh0et y9ep2 5 sc6vxvnct of pH, temperature 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 nebu d*5) fbe;qg9kzc to(z)0 cqed to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with neboqc0zb;k)gdt5 ef c z(9*q)uw 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.,5aoa9n5aaf c)xixd k axj2: an enzyme affects the rate of reactiof5:oa9an ix5ka x,a.d ax)c2jn.
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 broken8s:l v*rekhcc mw24s* down or synthesized through metabolic reactions. Which typ lc:4hmk c*w*s 2se8rve(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions canafw9m (f0rif2 be measure29w( arfffmi0d.
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 chemical reac ;eyr;-4 awrbk:j4 h+, sxtig5w8zbwitions, given waz5hxkt y8g ;sr:wb4e,4wr i +i-;bjone example 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.