Which of the following macromolecules describe a typicalj.)w)r.y empt enzyme?

  What type of reaction is photosyntid 5 k/4ieh8-ujt /ehhhesis?

  What is the substrate for the z*r8z,ypukl ssv20*x l*rzha)h:h+p enzyme lactase?

  Which of the following stagnkc h-;r ;otb5es of cellular respiration takes place in the cytoplasho-cbk5;r;n t m?

  Which of the following would not be useful in determining the rate of an en/(ru:e77 4x. yna.gbncia wjnzyme-catalyzed reactin4/ea .ar .j y nncx:bg7(u7iwon?

  Which of the following processes. wr tfcw.81wo may be described as catabolism?

  Which of the following statements is best depicted by the fig hi 4wa86fok1/qdcv8h(idl d5ure below?

  Which statement about enzymes is anmd7h:j i -n5au1vorz 5f4p6 not true?

  Which of the following graphs best illustrates the z o9 ;sou u7pl291rkflrelationship between temperatureuuz9 ;ok2r fol7lp9s1 and the activity of enzymes such as lipase?

1.Sketch a graph to show how inrw8n+el8teak5e7qhtrmz 0 4p ku8 g)7creasing concentrations of substrate affect enzyme actzl4wt0u 8e 7e5 qe8 knk7t+a 8hr)pmrgivity.
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 d+ (kc5rb.uh i,tx rg2viagram outlining 2cgi5.+b,xvr k(rt uhthe Calvin cycle is shown below.

The image below shows the 5a8ohe o*6+bte7z lhmcatalytic site of an enzyme. The substrate is shown in black and is bound to the ac6oa *7+m hbtlzoe 8he5tive 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 dv9nkn31pcy 6of the enzyme catalysed metabolic pathways shown bev 3kdpn91 c6nylow? Letters represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catayeo dp1/6qsf.lysed reactions1q6e/yps. fd o?

  Which of the following correctly describesnc0 v ,/-moujq photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving mul0gfls4v1a;a8 hlvpv;y .t/b ftiple steps and multiple g;l 1ha4;fp./av8bfs0vl v ytenzymes.

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

  Which of the following best describes the inhibitor in the im 2y5g5*my zb.fxkflu 1age below?

  Which of the following statements are true regarding regulation by end-product +j0ug; 9nozqdt. o v/einhibitg9vot/ u nz;.q+od0jeion?
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 strovx0/rgz 95ewufjv4)ucture in black is the substrate and is bound at the )f5/u0eg j vz9xr4 vowactive site.

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

The equipment below can be used to study the effect of temperaturei gvbe /k76-rk on the activity of the enzyme am7ek-vg br6 /kiylase.



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 describese/8f eq9) hht bvtw.h- how enzymes interact with substrates to catalyze reactiv -b9th/ e.t8h)qfw ehons?
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 redm y9s2y*3tgzwy9v1ieg q13sactions can be measured.

  How does denaturation change the propertie (.(hjhds t7u5j2dgfrs of an enzyme?

  Enzymes play a role in catj/jzus* lm8v+ alysing reactions. Which of the following statements arsjv z/m jl8*u+e true?
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 mammald( f7.0xbs tb,e.admhos10rpn *:s k:1pi vmss or endotherms from ectotherms thv(. 0rdk:bx:.mdb ophs mss107af*et1p,nsi at have fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product i/j)wrvo 7;94sftzloc :7q ii6.yer uvsoleucine consists of five reactions. Threonine is converted to various interm lc.q6 :);9vz7sewtvorouj iy4/ ir7fediate 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 enzymati *c;/j +lhonhpc reaction. Whpl h*+n;o/jc hat is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzv psmm :r)gk::q;hd*zymatic reaction. What could be the independent and dependent variab z::r vk q*)gpsm;md:hles in this experiment?

  The diagram shows the pathway that converts threonine to isoleucine.gd s0o bllqxx8,n) 3z)o0 zekp3v k3k3



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

  Enzyme A (Enz A) was imm vzpzcglvs4 4o:, wes 9/6)ujqobilized on a matrix and its activity was compared with that of a free enzyme in soluo glus) 6/wp:v qvzj,4z4e9sction. 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 followin sf1+tsxw ym g+:uzbg+5up+,falhe0 /g is the best way to keep enzymes actie f/ahyg subzgt+ s0wu x+f51l+p: ,+mve for a longer period of time?

  Which of the following describes some types of extracellulaystiq7-6(ntg am1xq7(b i co/r enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in px52 55gin r0jjb1a*c 2gaeu +vx of/pthe stomach. A study was carried out to determine the effect of increasing sucvo gia5 rf 1+j2*anpg0x xj5ubp/ 2e5bstrate 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 3.*zll k5o*nrjshn :i 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 r5zk rjln* nho:*3 .slieactions. 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 student cut a turnip root into small cuf d8+ f12xj8 afnjy:fcbes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homod2cj1fn 8a8 xf:+jyffgenize 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- CoA reducw(1h-y06tgxwnio78 tjzm (/er kx,zqtase can lower the production og8nxjzw0hmxti (qy7z wk (,/ro1 -te6 f 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 i 4.vv3tq:pxaonvolved 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 metabolc5 poi k2; xp (wup v8ae4.q5e .m2tlm7xveaf-ic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a .owp2xv5.(eck7-8qfl 5aa pm xv;i ep2 4m teucatabolic 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 ul0d-o5khuhdl8u lyhxey- 5lg4 )59 q0m vke*on the efficiency of lactase activity is tested. Which is an appro4-ee-50k5d m ux0lodh) lhq lvukhyg 85y9ul *priate dependent variable for this experiment?

  A study has been conducted on the a8y--n pjwi2o+ 5-sog i gs5x*ub vwrt8ctivity 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 produc2 -ort8jw i+-ygsig5*p5 8 w vnboux-se 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 fihajs0 bowuw ,a (6)i/nnd new drugs for treating patients with malaria. Describe how aosb h0/iwjn , (ua6aw)nti-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,)n(3a hpljj n affects the rate of reac)jpj n,3lha (ntion.
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 synthesi q 1hn1d1ls3idzed through metabolic reactions. Which type(s) of metabolic reaction 3s1qdl1id h1ns are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactgqcwdt:b61 bm./ g97da ld)jtions can be measuredlw a9mj1cg: 76.)/ dqddt bgtb.
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,rqsv * ) nm-iih/f0;jt n4qdog2xl, j7 given one example of each type of re) xldi sn* -htvqgo q f7ir2,/;m04njjaction.
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.