Which of the following macromolerqjl5m f0x br9 8:di7di 4w2eccules describe a typical enzyme?

  What type of reaction iwr4 dt nb.9rk4s photosynthesis?

  What is the substrate fora ob5a t*ru.,mfhq4p89 s(g bf the enzyme lactase?

  Which of the following stages of cellular respiration takes h;vlxh.r68ca w4up)an by8d-place in the cytoplasml r 8wyc-6vbhn xuaapd); 4h.8?

  Which of the following wouio5- i hf2yx wp+ )q/m4+qfbnfld not be useful in determining the rate of an enzyme-catqf5) +fwqf/i2+np4bxm -yohi alyzed reaction?

  Which of the following processes may be described as catabolisg57s( (zw-v.fon zrgjm?

  Which of the following stll (ihk2lv q8n4,nh0vatements is best depicted by the figure below?

  Which statement about enzymes is8:q fbr0c8ok.pdr;n 7yqz5f24u w*pw t se6qa not true?

  Which of the following graphs best illusieyg18v, w+e 4:kuaos trates the relationship between temperature and the activity of enzymes such uk g8 viyo4+e1aswe: ,as lipase?

1.Sketch a graph to show how increasing concentratixu918ht.xx ljivgwe 0 5kph4(ons of substrate affect enzyme activitpwk 51vl h4.(xi jeu8hg xt90xy.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a sesf c 3.ng3vj7q(v .pxqries of enzyme catalysed reactions. A diagram outlining the Calvin cycle is shown bg.3p (x n3vq. cqjf7vselow.

The image below shows the catalhyn140k9 g 5zs3iiy sgytic site of an enzyme. The substrate is shown in black and ik yy10nig i39zg5h4sss 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 catalysed metabolim:/2758mab us mtiwdtyqy9ns d;jr+ (c pathways shown below? Letters rsysr7ym ;t db2+8a 5u:(wmdtnj9qi/ mepresent various products of individual reactions.

  Which of the following describes the role of y +)s8dhf5/ztl p cak/inhibitors in enzyme-catalysed react+ dc8 al 5kzst/hypf/)ions?

  Which of the following correctly deamxxgy r2:3z 7scribes photosynthesis or respiration?

Many enzymatic reactions happeng:1 h abz+rriuk ;:x9k as pathways involving multiple steps and multiple enzyuxa:igbk+ r1:k ;zr9h mes.

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

  Which of the following best describes the inhib08rzi98xgi mz itor in the image below?

  Which of the following statements are true regarding regulation by end-prodj1i7nsab der zl-zkk 9 kr5234uct inhibition? 2rr4zkk- zk5i 7j dn3 elba19s
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 thegu)3bhkeo/9pz qq /7w lysozyme enzyme. The darkened structure in black is the substrate and is bound at the active sitkphz) 7gebu3 q/ /woq9e.

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 ax5ph(*/6 1aghvwlp j2y,/ so7ndqp nsctivity of gnpp2yvsh6/5( x/ 7 ,waodhs*jpq1ln 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 describes how enzymes interact with 5kh e8ue0)ou-b9kh r wsubstrates to catalyze re )ewk-8he5 o0r9hbkuuactions?
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 reacti-xh7.d 4svwxa h,s6*wr)r+ o ju6 itkmons can be measured.

  How does denaturation change the properties of an enzixcsy +on)0p) yme?

  Enzymes play a role in ca-+hewtk dpyj1kh- at (rh+) q/s3 1bhftalysing reactions. Which of the following statements are tru)h--qk dy1h 1hs/ebfj+wr ht3(tk+ape?
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 tb(+ir u44m p5 ctnebq(+ay:nmammals or endotherms from ectotherms that have fluctua ny+b4iq:4upn ret5ca+tb((m ting body temperatures?

  A metabolic pathway that converts threonine to the end-product wo+kn.w5k2i xisoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last wk.w x5o+2i knenzyme 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 tiul:j z5yyoec0- yv)2he rate of an enzymatic reaction. What is occurring during the c2 -yy:y0 z)juvil5e ophase labelled section X in the graph?

  An experiment tests the effect of d /c+ekrciv;4kxox/ 4changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in thd/ ov4e4 x;c+x kki/rcis experiment?

  The diagram shows the pathway that converts thr66ty5*t0;g9 2dxqp vtqhuzso eonine 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 compac-z;u 9f fq/sored with that of a free enzyme in solution. Th;osfzq / cfu9-e 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 following is the besa(,p0xx qi pay4h5hz ,t way to keep enzymes active for a longer period ofiq,xh p5( x,hpa z40ay time?

  Which of the following describes some types of extracellularsp7l tfj +s;si*q245mdj 6a pb enzymes?

  The enzyme pepsin hydrolyses proteins to release wtysnwf xyqoms0;:5c,of :87peptides in the stomach. A study was carried out to7wtys8sf m5 o xqc nwf:,0o:;y 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 rate of reaction of an enzyme with increasing substrazabw10leqru 7d(:kq*te concentration. Similar concelbq0 7(we1 kd:uqarz*ntrations 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 enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activit bst77k:4-)xmsivd ie y, 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 b s)i d4 x77tesm:-ivkblender 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 e4r+d pu, k5pzqf*j6cxnzyme HMG- CoA reductase ,pc prq4j*d6+k5 xz ufcan lower the 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 are involved injfr awloc7)+z-63oat ;a9rk w 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 classroom7/j zulez 2(3kgvs p1r and were given an experiment which demonstrlk7(z/uges 1 p3rvzj2 ated 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 efficienw8hba7o2 s 2a lt/zl9rcy of lactase activity is tested. Which iwla89s l2t/7h rob2z as an appropriate dependent variable for this experiment?

  A study has been conducted on s vz-pd 2uh:m5yq-3 dythe activity 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-free milk. z2su 5 d-hyqm:y dpv-3



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 treatin4ky ej9p*.qdw9;yey u g patients with malaria. Describe how anti-malarial drugs yd9* ew4epyq.9 kj;uy 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 eege oz 5w 8ct53;ug9*ig dr62rje1ldrate of reaction. ;uw 6z g lcer5531je ggde2* oi8d9tre
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 th+gk.0e16 ;d wuxreysurough metabolic reactions. Which typ.udw+60esy xugre;1ke(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 be m 4azbilm4c80 heasured mci4 z084ahlb.
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 m9t4hkuh h8xsy (wsoz4w;c;i-2(wxv reactions, given on9w y uthxv4o2hs4kxi8zm(s ;-cw;( whe example of 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.