Which of the following macromolecules descaz0jm 5n+( yw*pjj 0hgribe a typical enzyme?

  What type of reaction is photosynthec) u u34io1(wzum0ivb sis?

  What is the substrate for the enzyme lactl8r7e.+fy f y0j/,jv 8dxe,gg ezem/gase?

  Which of the following stages of cellular respi3lzs-afg3igl: d;t c+ ration takes place in the cytoplasm? c- t3+l fl:s3dzg g;ai

  Which of the following would not be useful in determining the bm e:a,fx /v;zz) 1f-tz;tfrq rate of an enzyme-car:, zf/;;e mfazftt -1zb v)xqtalyzed reaction?

  Which of the following processes may be descricnver-js l.svt 38ky3u/2 w 2cbed as catabolism?

  Which of the following sta 6;6gx kc7ouzvck2i1 dtements is best depicted by the figure below?

  Which statement about enzymes is noy54za yb55y i:jim h+dt true?

  Which of the following graphs best illustrates the relationship between temper:9rz+:) 1fnudn u6l pa /syhd bkp/4bsaturd kn /apypzbu/1 s 9nbd4)fhr6l::su+ e and the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of suvsx041jtxr ;tjxqo q 7t69* llbstrate affect enzym tx; 10jvjx4l6*qst7 rxq tl9oe 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 diagt7m9h/ 5clbkwram outlining the Calvin cycle is shown hc5 w97tb/kmlbelow.

The image below shows thp 90 i0uhpom 8r p2+x1kbongww6y)m9 he catalytic site of an enzyme. The substrate is shown in black m2i0pu1w6 9yp8r m0 b9xoo) +phhwgk nand 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 catalyse-dyfcuitdn yl7a)2k+5r 8w( s d metabolic pathways shown below? Lettersw(2 r7+ 5dyd )clyi-kaf8ns ut represent various products of individual reactions.

  Which of the following4ikwh*ta uua7:8 8l ww describes the role of inhibitors in enzyme-catalysed reactioa:7h8aiukuw8 t *w w4lns?

  Which of the following correctly describesa0l) 0cpc a1 .kvh93sxd b-obt photosynthesis or respiration?

Many enzymatic reactions happen as pathways invdaucu z ,7g9cg un9)v*olving multiple steps and multiple enzymes. cn ,gu*9z dvu9u7)gca

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

  Which of the following best describes the inhibitor in thtv h)y/,l/+ntpc) uxoe image below?

  Which of the following statements are true regzqxbsqqj1u4h;ud 5jqj6v1 a+o 9:a6o arding regulation by end-product inhib4s zuquj v1+a:q b15q 6;qha6 jo9jdoxition?
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 lysozyt9vyx9hay 4 7;tm,sfime enzyme. The darkened structure in black is the substram,7y994 xy; vfatsith te 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 fv: ;pr6zo;x oactivity of the enzyme amylao ;;r zfpvo6:xse.



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 describes how enzymes interact with1oh.n (:qg/zb83 vxpvc xw0cr substrates x30qv:n.c(/gw8or v1z bh pcxto 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 enzp.www7/bks 4*:r1fy ocv1cc m yme catalysed reactions can be measured.

  How does denaturation change the properties of mvlqse 1v7 j;)ibwjxn6sn8*, an enzyme?

  Enzymes play a role in catalysing reactions. Which of the fo x1c(y(c)pdhtq-e1 x allowing statements are true-e1 phtd ()xy(cxcq1 a?
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 pb:gh) 7gq7mr7,j) c pzi 8ccuectotherms that have fluctuating body temperature) cbz7gp7iru c)7 8,hcmjgpq:s?

  A metabolic pathway that converts threonine to the end-productzc7e,u y+y k5venqdks/ ( *so;wcn 77co6cc)j isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by thy*dy(knw+n) u,ckccs7 ce 6cesvj 7qzo5 /o7;e 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 enzymatgo 5*n9xsgr8/v0p dfh ic reaction. What is och8f pr5n * 9g/gsdxvo0curring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzymatzag9y-f+/fzpgste06 vd o:2s ic reaction. What could be the independent and depep 290zgt +oydasz /fvfse 6g-:ndent variables in this experiment?

  The diagram shows the pat1g-6dnyofos. hway 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 wbo) 3ox).yvrugcog gl4f6 q)e8* 6m2tjc0s fmas compared with that of a free enzyme or)bgovu0 t y6j8.lmg 623c )f4)efsgqox*mcin 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 easiluvy 2drn 5f+ c,2/q*v hsu5.qkz7goho y denatured. Which of the following is the best way to keep enzymes act5vq+cyvg. 5q fhsu2hoo*z/urdk ,n27ive for a longer period of time?

  Which of the following d)vaxrod6 ywd(x9i 7x3f6;apmescribes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to relealq pw:fuud)1 .sz f i17gmpc l*+an48yse peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperat.zu +alu*1:) f psmynpd 481icqfl7wgure 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 opselvff(*s z .qn,)3fwo8)o of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the act8p)s q3.weo)f * ov(f,losnfzivity 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 activitx/*vohm ajp- riv6a1/. ybi1v y, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish ia.61 pvbj ioy*1hm-v//xrav, 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 pathwayt1g5 u xp*nn5b is shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the production ofb51nt 5g x*pnu 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 followinglo6 jn/w1st 3m uh..el are 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*:fm;slauk:tr4)jm; 4*ne0ao ap ucz reactions in the classroom and were given an experiment whichf jp*0s 4 :aeuana)cm *;zum;4t :rlok demonstrated 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 ef;li9a/(w++o mb oyas nfect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this+9w+sol/a n(iabym;o experiment?

  A study has been conducted on the activityf 8lu*q f78r 0b8 yh7qsjh5ubv of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactose-frv75 8hbbu0* hrs l yq7j8fqu8fee 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 drugp 9 8k+1 n-bb1zjr cn-;3)kuyoglkydn s for treating patients with malaria. Describe how anti-malarial drugs are being discovered with new technologien-y-lyk p+) 38kj ;knurg 9cbzd 11obns.
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 affect je3bf:h;ktl+ .pb5m *jq 0dg0tbuv8e s the rate of reach0bq8:0e; gvb bjjtmul3.f p+5ed t*ktion.
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 metabol u*n 3zmn vvl9g6man91xpy5u1mgyz; :ic reactions. Which lym9y31g nuv6mz n v1 xap:;59*mugzn type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can ln2 4 a yxh9t8gf7 )floi4,pj6t wprj-be measured.rhpj ol yjx47a8i n6, 2ttl)w4g fp9f-
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 contray t0 +/te3p .dsdhz1ibst intracellular and extracellular chemical reactions, given one example of each type of reactio te .p3 ihd/s+tzydb10n.
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.