Which of the following macromolecules describe a ty d hl;9i;:fg,pkn-sbk pical enzyme?

  What type of reaction is photosyntyyc q(;y)0xz nm,3c hthesis?

  What is the substrate for the enzymezzr9 0pr*qb(vz b 0ul. lactase?

  Which of the following stages of cellular respiratx0 :h2ud y 9hetqx;)d3/ . dcsetrxj/cion takes place in the cytoplasm?0cx:3 u)j resq;.2e/hytdc xdxd /ht9

  Which of the following would not be useful in determining th ,x/cwnhs yp*7zx10fj e rate of an enzyme-catalyzexn* fpz,wxch71s j /0yd reaction?

  Which of the following processes may be descwpx3j)o+d+ 7 rye7 mcr6 3itrsribed as catabolism?

  Which of the following statements is best depicted by the figure belof (kg8h z;;nqilo:p*ow?

  Which statement about enzymes is so f/-uhwx-cft6y)gv.(ibgl + hf+-s not true?

  Which of the following graphs best illustrates thynstp()7q.p c83mu zs e relationship between temperature and the activity of enzymes such as lycm8u) pp7qn( 3.tszs ipase?

1.Sketch a graph to show how increasig26i /pw:y6ogib6lum ng concentrations of substrate affect enzyme activit6i g y6pglbioum6w2:/ y.
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 diagrwl* g +mo8mxj;,xie(r am outlining the Calvin cycle is sh(xmr el;i, o* +8gjwxmown below.

The image below shows the catalytic site pf;9n9njdcj1 +9i exaof an enzyme. The substrate is shown in black and is bound to the activj9 +9nd;afcx pn91ij ee 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 thehbivv0 -y 2*os enzyme catalysed metabolic pathways shown below? Letters represent various products of individual react2s*h ov-0vbiy ions.

  Which of the following describes the role of inhibitors in enzyme-catalyse)9hh0fkr 1s/ fn6h(4v qa vzhkd reacti0hnf1k / kh69h4hqzr)vasfv(ons?

  Which of the following correctly describes photosynth.a -v qjrojk iz4i,+k/esis or respiration?

Many enzymatic reactions happen as pathways involving +lm1w25,orots f:ejfct6v - n6 8vyljmultiple steps and multiple enzymes.1jrjt6f feo+:6 ,v-5 llscw nm28vyot

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

  Which of the following best de ,nw,n* pj7i eiagfa1;scribes the inhibitor in the image below?

  Which of the following statements are true 59v ura*rzc8s6tyu3) u9od5am r-diyregarding regulation by end-product inhib 6u oyd3 r-vi5ar*acusm5 z t)99rdy8uition?
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 enzy+wrqagf+r3xdsznxn..y 3yoi+ (l- 0x me. The darkened structure in black is the substrate an03 n3-dya+yg+rql. osn+ir x.z fx( xwd 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 oys 2:jox(vfax;1 3wpj n the activity of 2 xajwoy(xv:fp1j 3; sthe 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 describevxk5j cb 1nbyz1f e0v.m8t 99ss how enzymes interact with substrates to catal .9fmebt 19yv0s5bc8 z k1nvxjyze 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 enzyme3btm6 w9nu.a**t)wrsvrsgej nb b 5 65k(er*t catalysed reactions can be measured.

  How does denaturation change the properties of an end bxs r2zctd 0o*w4u:2zyme?

  Enzymes play a role in catalysing reactions.gw1p(o a;gi;g Which of the following statements are tggwp (; i1;aogrue?
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 endoth (bh:;k1do vi17gufyyerms from ectotherms that have fluctuating body tempera bd;fiok:7vghu1( yy 1tures?

  A metabolic pathway th56; ealon fx6,6ot60 +l+edl rzsof faat converts threonine to the end-product isoleucine consists of five reactions. Th0ofo;d alest a++lzlrxf ,6on665f 6ereonine 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 enzymativ*yn lz1:rnna ko r9/:c reaction. What is occurring during tzkvro:l9r nn n1y/a:* he phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentr7fl64 0gdftzd ation on an enzymatic reaction.f 40 fltdgzd76 What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway thao(x(gy8d -ws zd)o)i5gxc /cp t 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 compared wit(k(fj(bnpdivu9 os z()u7 kn f/ av,c+h that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with vapcajvdv9n (o /fi(bu k(f,znk(s 7u+)rying 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 denatu ;)prclq rvsx- ez 07x-s)fnr+keht(1red. Which of the following is the best way to ek (n -fc+zv ;rr0ex)xl) r7q1pss-htkeep enzymes active for a longer period of time?

  Which of the following describes some types of e33dyzho )z3 csxtracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the st)m84j 8 ei (c62)xmb qcjngeamomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a 6ee8m4ja) mn8)qb m(gcic j 2xconstant 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 ofk)w(f+mo j qkr-)x g)j.-.akydqflv4 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 coincidjdf))- k -k +qjakry .f)xlqg(4mow v.es 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 activi)l -ntab 1ly jud/5wqocc. :g+ty, 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 homogg)w:t +ul bjc -5d.cynalq/1oenate 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- CoA rexws5 aki)16ng/ e qun-7 h+dinductase can lower t6n k5wi/)d7 -uqnnehaxi+sg1 he production 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 as8xtxno(ww*y(fhh 9 ui( (:z hre 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 metval;sr6 av*vld)ey3 i/)- kyv.x b;muabolic reactions in the classroom and were given an experiment which demonstrated the effect of 6l3)iavr;*l y-s/d)vbm uvav;k .exytemperature 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, themgx 303a1wxt z effect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate depende t10gwxmx3a3znt variable for this experiment?

  A study has been conducted on the acte:ynuh;/1h yq 9lk2 qtivity of a specific lactase (Bg10), analysing the effect of pH, temperature and ne1;h/:ht9ylu k y2qq 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 a,7m/z5 zum(fg-u(mu5he rikdrugs for treating patients with malaria. Describe how anti-malarial,( - f/5ukamz75 zuirgmhe( mu 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 radpyu1qaj ; *vh1dfh68te of reac1;ydj h81hf*vpa6u dqtion.
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 reaction7qruewbcj*jzd kji,e4 /0,+n s. Which type(s) of metabolic reactions arc4qew07 ,j/j,iknb*de u+ rzje condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of efp7b3h cm94qh:ym.ffm2vx 8 nnzyme catalyzed reactions can be measured. q x:h 24vmpmm.b 8f3f9yfh7cn
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 reactions, 5d c-ubh9 -hhogiven one example of each typouh95-hc-b dh e 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.