Which of the following macromolecules describe a typick9k 7d.4/(szjt v:gt2 uaqesfal enzyme?

  What type of reaction isnq8on38 hz+hi(m6 uqe photosynthesis?

  What is the substrate for tx /,h;*v vcqothe enzyme lactase?

  Which of the followiofe g7mef ql /3z8w90lng stages of cellular respiration takes place in the cytoplasm?3wmqeof l9 7ge8f0/lz

  Which of the following would not be useful in determining the rate of an enzymed9,v2ro e ,jni-catadn2,9 eri ,jvolyzed reaction?

  Which of the following processes may be de7 qt7dn ai6jwkd;rz(yoo+w. -scribed as catabolism?

  Which of the following statements is best depez8nna )o l8r)l9fwr*icted by the figure below?

  Which statement about enzymesk ,f.o 2f5 z.y4gzhbll zecw4+ is not true?

  Which of the following graphs best illustrates the relations lp/*xw.uddd2hip between temperature and the activit2ulxw ddp */d.y of enzymes such as lipase?

1.Sketch a graph to show hnrhq 6h2fpk3g/e2+ vuow increasing concentrations of substrate affect enzyme actknegr up3h+f2 26vqh/ivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a se4 m 2k7mzqjd-cz w8d 4f4-tpxories of enzyme catalysed reactions. A diagram outlining the Calvin cycle is shown below. 78d -cm4m jz2k qtdw 4-xof4pz

The image below shows the catalytic site of an enzymef -;-0f3 g5unejcmq am. The substrate is shown in black and is boundc;f-mma0efgnj - 3 q5u 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 c(uq : nrw2+1pkhs tqpo);qj-o;d q *gcatalysed metabolic pathways shown below? Letters sg:t *o-q+; jqn1hqkw qp2)(ru; codprepresent various products of individual reactions.

  Which of the following describes the role ow2 zcu pn.hd*ddk)zvj8 (v;p 1f inhibitors in enzyme-catalysed reactiond18pc(zdd.w h 2u;pvnkv)zj* s?

  Which of the following correctly describes photosynthesis or respiratm4 8/:mrzx jwcion?

Many enzymatic reactions happen as pathways involving multiple steps andvz ix h2;1 vb,soh(m7j6wv m2g multiple egx v z6bhwv2mmho ,2; (7vj1sinzymes.

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

  Which of the following best desz2/9p3qjgl* (pj8wr 5ulrbv ycribes the inhibitor in the image below?

  Which of the following statements are true2l(ym + my )6yv88mhea rym/pm regarding regulation by end-product inhibitionl(my8mm6 ramy 8e+h y)2vm/ yp?
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 structurj m8ejv s) xy)bl+3ul+e of the lysozyme enzyme. The darkened structure in black is the substrate and is bound8+xul ej )lbmjvs)+y 3 at the active site.

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

The equipment below can be used to if fuw/s4 6)vvaekn.0study the effect of temperature on the activi4v)wk eu6 a0inf/fs.vty of the enzyme amylase.



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 del*za,rttgv,b :yplfn 2 33c)l9g a -6z;nbbebscribes how enzymes interact with substrates to cataly:g,6pncl;nl -b f )3ybalbb2*vagr t zz9t3, eze 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 catalyha5qmr4+qknqm2ncf0 ./zx l*sed reactions can be measured.

  How does denaturation change the pqn 4h*( kzh *ddowi+j5roperties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stateme8p :i 2cu dztbo5.m-:bp6bkan nts are true?z:.m5au6-i t 8pd kpo:nb b2cb
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 fromqpy/8njan ): e4xknw7 ectotherms that have fluctuati)748:p k/xwnj n yeqnang body temperatures?

  A metabolic pathway that converts threonine to the end-produccjeatarm 79t ;(svqrkd +a5**t isoleucine consists of five reacti9c+*5d7jr etrms*;qa kv t a(aons. Threonine is converted to various 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 increasing pH on the rate of an enzymat0tr 9f37tih m(8kl;pnth 2hg kic reaction. What is occurring during the phase labelled section X in g9(28phnhmk3 f7;tlkri 0httthe graph?

  An experiment tests the effect of changing substrate concentratio3oo: dbx(8ddo n on an enzymatic reaction. What could be the xd doo8d:(bo3 independent and dependent variables in this experiment?

  The diagram shows the pathway .if1v2 sbu uvz- vt7l(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 co4xe;1zhcrlsifois(y 9+d7b1 mpared with that of a 79; szeyfx1ii cs+ o41(rldbhfree 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 denatured. Which of the follow5/kl 7dc8g f9n)s 3tc c4p p8alih4meuing is the best way to keep enzymes active for a longer ec4983ml5 n/glipsca h7 uft8c)4pkd period of time?

  Which of the following describes some types ofyr/yo j;g1yzsvlr: )zb) * vc, extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stp2vb gf/ ty0,tomach. A study was catpv 2tfy0,g b/rried 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 ratvb 5 ucph9cq9gv (vf2+e of reaction 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 enzymqghv9(5+9 b2v pvfccue with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme a(ybu;0fl nid3 h6lev2 ctivity, 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 homogenate was filtered and the liquid extract was stored in a test tube at room temperature. 6hvy ;elbdfu(i ln 320


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 shog dqco*1lb--2fi)x tn wn below. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholesterol.iq)-2xcbf-d t*n og1l


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 denaturation? .wnti(q 3.eniyy .0t;.l fncv
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 investiku 9+dp9o96dup xgm4m gating metabolic reactions in the classroom and were given an experiment which demonstratmdux9m6 d9kou+9pg4p ed 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 effect of increasing temperature on the efficie+uoumr(*tw j30kn kc ;ncy of lactase activity is tested. Which is an appropriate dependent varimrot 3kc0j un;+uk(w *able for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analysl+ftrpp.-o) ,fgy4dyfwz 1*-63eodh oy w)rxing the effect of pH, temperature and glucose concentration, as it may poten+fy*4- rgf. d1,fye 6zthwo3o) oxr)dl- p ywptially 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 nee,ny xap9ofdu42qs/ b q. px)t.n).vcid to find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with new te..d vcx9 x)tioq,/yqb4p.uans fp) 2nchnologies.
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 *k8+o nri.mvc4czl*a rate of reacti*vlkzi c8cno+ .4*ramon.
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 reactions. Why n+esk. ;xzw8ich type(s) o8kz.+x;yes wn f metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be meaploa) -mlr 85 mk0p(0wpot4yesuyopmr l4 mek )wp58t0(0-lpoa red.
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 ext83yhz 11x ok s 4x1ljvrt(yuh*racellular chemical reactions, given one example o yhu*8(szyxj1 t4l r3hx1vk1of 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.