Which of the following macromolecule3a7l3 x gzitv2s describe a typical enzyme?

  What type of reaction is photosy a5rmp+f0 qg8r/en9m jnthesis?

  What is the substrate for thef r(67:1e pu*nuon cgj enzyme lactase?

  Which of the following stages of cellular respirat :ev5j3-hmj3ny/ x/qid wh6ajion takes place in the cytopla :3jyjje6w in5h/ d -3vxmqah/sm?

  Which of the following would not be useful in wlj*b1pjp.29timtvici8y;by+ * 3 b rdetermining the rate of an enzyme-catalyzed reabt.*3 v ypypib9 l2jm b8itri+wc1j*;ction?

  Which of the following processes3 fd*xqd0cr (v may be described as catabolism?

  Which of the following statements is best du rxat v dbut9*:0/f6tepicted by the figure below?

  Which statement about gms;l.t7okiq8/r e-qenzymes is not true?

  Which of the following graphs best illustrates the relationship between tempertepr -g+2 :uyy5ln0x mature and 2ue -l0 +t npm:5rgyyxthe activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect 7z grx)p.h4wx enzyme activity.4 zh. wpx7x)rg
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed b nd ov8+vq5(woql/ vh2cnf/1reactions. A diagram outlining the C c2v1bnfdwv/vqo(o/ hq5ln +8alvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is show(.g cov: s z*:;4uey)uz rtfmtn in blavg.:tzo*f:uy tm u(rzs) 4;ceck and is 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 descriptions of the enzyme catalysed metq; tw63 ahkgg)abolic pathways shown below? Letters represe3 wqhk6gat ;g)nt various products of individual reactions.

  Which of the following d nw 0j*jr3 rybm/ocg26g y/1gcescribes the role of inhibitors in enzyme-catalysed reacbrog 2/jcy0/g6 3r*y jcnw1gmtions?

  Which of the following correctly describ nve4,ib+((su5 b )e sl*g ss-g0jnkvges photosynthesis or respiration?

Many enzymatic reactions happenkgx;n emw gx-0 1p z:sr;.rln6 as pathways involving multiple steps and multiple enzymes-n .;s0wr;xg6lxg zrp:e 1n mk.

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

  Which of the following best describes the inhirxd 4, a- e2y efq )y(f-hrmfboa32jd+bitor in the image below?

  Which of the following statements are true regarding regu 14qxx)gdyx.p lation by end-product inhip g4x )qy1dxx.bition?
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 o8* qp4f3- zcpt x7mdcgbe :n 2;wc8oatn, ha-cf the lysozyme enzyme. The darkened structure in black is the substrate and is bound at h ftx ;4-wgt8zp7: a2n3e8b qcmna,c c*op-dcthe active site.

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

The equipment below can be used to study the efv v /tkfjc 8zz9 78uyj)w)8nfzfect of temperature on the activity of the enzyme amylase.ckfz)8nz /z89w t8vjy)fj7 vu



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 describelc5f y1sgo5,iu8krh 3 s how enzymes interact with substratesoi5 fck,su rg3851l hy to 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 measuredo3w 52 pdg:ayaj 9re3h.

  How does denaturation change the properties of l)qbg); owa8) jw5jmg an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stateg5jh;or3 +qbjp6sfm5 ments are true?ojq rh mspj+3f5 65;gb
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 m49d 30dsprj5.ob kw:q4corwjammals or endotherms from ectotherms that have fluctuating body 0:ok3jjs4owqr9c4 dr. dw5bp temperatures?

  A metabolic pathway that converts threonine c clg4fz +ar,zd3-y 5hto the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by difgfyz+ c l5,z3cha4-dr 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 incb9 ojx t 58lze ta4uolah79p1,reasing pH on the rate of an enzymatic reaction.1l8tx 4a t,hoj e 5l99a7bzoup What is occurring during the phase labelled section X in the graph?

  An experiment tests the cqac, xgzn,2 5effect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in tx, , 2gc5zqncahis experiment?

  The diagram shows the pathway that converts threonine to isol s:e 2)u3aj cmk,2d kessd,i-veucine.



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

  Enzyme A (Enz A) was immobilizedx,a75i3 h gu(oqh v(zd on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH gvihq(ha o xz (u753d,(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 thev7a 5d:b*u q8jsh )gfw best way to keeph) qv:5af 78gsd*bujw enzymes active for a longer period of time?

  Which of the following describes some typkp6n5n8i dd;t es of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptqbp-y,d7fyg.2clq x2: rum)q ides in the stomach. A study was carried out to 7 q yfg2x c2qy -).ld,mbprqu: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 enzym y2 .acgwzz5j9e 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 wzy9 w gj.caz52ith 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 rootpbb,s4 -i5oor into small cubes. They measured approximates-iborpo, 45b ly 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 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 h6crk *bn2q37dj 4bvqf+yu 2yshown below. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholesterol.+dr h4 knyv2buqbf3 c7y2q 6*j


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 q (yg7 d/d4e )0efkyjjinvolved 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 metabolr 5dpt5 4n5bmy) mbd4gic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic reaction. ) 5mdpdg rbb445mt5n y
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 i)l,k0nrc c 7m .tmxyy-ncreasing temperature on the efficiency of lactl)cycn ym 7,mr-.k0xtase activity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg1ia 0 kwacgj)ob 7e6o/k wt5v560), analysing the effect of pH, temperature and glucose co60kev5wogo a/j aw)it76bk5c ncentration, 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 e5 ,e1u4c :mdc ez )a6xpyh1csm 794c+wwmdwifind new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered wed 5 w7h4)c zm9ui dyecmsm41w1cac+:,xw 6epith 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 increasoo3fggl0+yb;k5 jrggrd: d ant4.2hb n 5*.s ling the concentration of an enzyme affects the rate of reaction. o.t5lo0fsn+ g5.*rj34bdl; rahkg2g y dn:gb
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 synthe4ss ,sb2mcy9h 77q mw2wjk5pjsized through metabolic reactions. Which type(s) of metabolic rw72ypqhm2mb7 jc,ks 5s js9w4eactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzwlkjt:,q6*pn1 t8ehqriy8 s 8yme catalyzed reactions can be measur8lqrtt8i 1 *p68js e:qkyw ,hned.
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 vfgnq* ) hw2s.genk-.reactions, given one exn.q gn2gwv *k-)shfe. ample 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.