Which of the following macromolecules describe a typicdghg4l * pbirz(e)3 1ral enzyme?

  What type of reaction is photosynthesiswhc3 det :+6f9 fng5tu?

  What is the substrate for thek4ij4rb n2n0/ hdte9s n 6h-mh enzyme lactase?

  Which of the following stagesdgezgk5)fz xx c0:w :ox4m *k1 of cellular respiration takes place in the cytoplakfxz ze*4 m)xgw1 5gdcx:0o k:sm?

  Which of the following would not be useful in determining the rate of arhq1+ ej mt+8bn enzyme-catalyzed reab+j hr 1qme8t+ction?

  Which of the following processes may be desca.;3i q )pp56 knuydu4gqlk6e ribed as catabolism?

  Which of the following statements is best depicted by tyr ne3jo)p ikd + r)t0vyx;c5*e2f;mwhe figure below?

  Which statement about ) qe8(fk;2cv:elqtj jenzymes is not true?

  Which of the following graphs best illustrates the c5g0 :jm. cpfmrelationship between temperatu.0mjgcf 5 cpm:re and the activity of enzymes such as lipase?

1.Sketch a graph to show hoyc uli -rriw:8 ef4rsje+40zw-v i02pw increasing concentrations of substrate affect enzymes yr4j iv fr 8w4wl0ieue0zr+2p-c- i: 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 diagram outu:i6qz 3vs19-v/ ouqmuxu u g+lining the Calvin cycle is shov uq uusx-vio 31 uz/+:uq6m9gwn below.

The image below shows the catalytic site of an enzyme. The subsznq d-ms z/q. vt.ev(gb*e9c )trate is shown in black and is bound(v q-*)g .dbv9ent/ze zqm. cs 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 n6j hquhdtn+6br, ob2m fd+,q5i a9 b6enzyme catalysed metabolic pathways shown below? Letters represent various products onijd+b6hd h5fbaqr, 6,m6q9un+ 2bot f individual reactions.

  Which of the following describes the role of inhibi8hzt co ff7pnrob/- 0)pua.1 2f:kapttors in enzyme-catalysed reaction20 a 1np8fboff /:r7kpt- tpua).hcozs?

  Which of the following correctl*zbv+k8fct9d y describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways iy ezcumj *2*5mnvolving multiple steps and multiplceu zm5*2* ymje enzymes.

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

  Which of the following fe(q yzddvs 4)1wbi1:best describes the inhibitor in the image below?

  Which of the following statementspto1h /exe) (y,k0 xzs are true regarding regulation by end-product is) zt1xp ,0/ohek(xeynhibition?
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 lysozyme enzyme. The darkened s sy4uyndcgu;y75a(g )tructure in blacgu;uy5d gcy( y 4asn)7k is 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 study the effect of temperature on the htbvrs,*b :6ow9zt54ysb 4 roactivity of ws9z:5rhbb6bo 4y4rv,to *tsthe 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 dp 6 +q,6ymri r;2utiifescribes how enzymes interact with substrates to car + ii6q ur6ptfi,2my;talyze 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 measo0/r40z tn:*kfzmou--ra so t n9)iu lured.

  How does denaturation change the properties of an enaaxf+: 0we, , gav-do6kjja n8zyme?

  Enzymes play a role in catalysing reactions. Which of the f1)fv 5-x*r y ,zsmiilcollowing statements are trisz i*5,yr cm)v xl-f1ue?
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 characteristcxc;fs2y ak /5ic that separates mammals or endotherms from ectotherms that havexfa;52 c yks/c fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-prod-(k:ldw4 hull z7fz9h uct isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isole 7zuf dlh(w zhkll4:-9ucine 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 onb 1yswuumq8+* 3osw- /ddkt m7 the rate of an enzymatic reaction. What is occurring during the phase labelled secto1wdsyus u/q+b*7- wk83 tm dmion X in the graph?

  An experiment tests the effect of changing substrate concentration r3ijx9d1qwy ;on an enzymatic reaction. What could be the independent and dependent variables inwi1r3d;jqxy 9 this experiment?

  The diagram shows the pathway that convpsm()q 3n 5r fzrxcr,-erts threonine to isoleucine.



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

  Enzyme A (Enz A) was im wd(4(5 oddl17+dnqux(p)eudgh6 xd(; zqv mlmobilized on a matrix and its activity was compared with thm(dx(z+ (el p5 6q1 ld wq)d 7uvddnuodg;hx4(at 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 arew4kc;x5at 2tf easily denatured. Which of the following is the best way to keep enzymes active for a wxt5; 42cka ftlonger period of time?

  Which of the following describes some types of extracellular eni ly2 ik)p2ttohs jo+-q :v5e--fsp)kzymes?

  The enzyme pepsin hydrolyses proteins to rele(xt+w)5s:iud x oam *xase peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzy m(a dui:x*oswx)+ 5txme 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 increasvue4q;ya o,7q9dl u6ping substrate concentration. Similar concentrations of chemicalsy ,679d4uqa o;vpql eu 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 no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a studentwh(c33mojkryu6dd5 0wp;0vs cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a bdskvm(5d0j6y u ;whc 3rp3wo 0lender 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 shown below. Inhibitors to the enzyme HMG l,+zce9 *n 7bftpu3rs- CoA reductase can lower the produ fblten,rz97 cp+su*3 ction 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 involve poue4p 0fmt,ld*cgt1 5.sp f-hqt);md 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 in the classroom and weneertcx57ni p v3 1 5q9x52cwere given an experiment which demonstrated the ef519xwcn2 nep q 7r53vcti 5xeefect 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 (+o*i32ck-;nuyr7 ga h4 2bia2 jzu pqekfmy5of increasing temperature on the efficiency of lactase activity is tested. Which is an appropkzjcr oqm2ya y g-aniih73*;(upf eb542+u2k riate dependent variable for this experiment?

  A study has been conducted on the diym+. (k(u to:jm/ ciactivity of a specific lactase (Bg10), analysing the effectyu(ik dm+/omj.i: c( t 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 need to find new drugs for ts l(:*pj5rmtf hl /jg3reating patients with malaria. Describe how ant(gms5/hj 3ljtf* :lrp i-malarial 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 enzyme affects the rate orm,rjyaqmd;4 +e u l.cv*g.5lf reaction..+q;c, jav*rlr.m m e gdu4ly5
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 o az(m14y g)ykwr synthesized through metabolic reactions. Whicmyg1(w)z a4yk h type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the7xg6rhe 2rgu 0 rate of enzyme catalyzed reactions can be measure 2g7u 6grxre0hd.
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 intru q)9ccnfk, - p;+ewxpacellular and extracellular chemical reactions, given one example of each+,xp ucep9)n cqwk-;f 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.