Which of the following macromolecules describpv d5l 9e2 eroe3v:iws9x6/yl e a typical enzyme?

  What type of reaction is photosynth-4 t31+n wh4hfuvugnpesis?

  What is the substrate for t z7bi/a77 lrdahe enzyme lactase?

  Which of the following stsxst2./ kla1oiz 0wt-ages of cellular respiration takes place in the cytoplasmxatw.ltz0/ kso-s1i2 ?

  Which of the following would not be u n1i.lo2n kdd4seful in determining the rate of an enzyme-catalyzed rn4kn do2 1.idleaction?

  Which of the following processes may be descr8y p )p11ngq,jvys)**d rqydiibed as catabolism?

  Which of the following statements is best depicted 8 qjm as4lagg )7k; 3w;bioyz*r-,cawby the figure below?

  Which statement about enzymes is e1+ fki ms5wj8not true?

  Which of the following graphs best illustrates the relationship betweew9 v2z 4lz/ktbpj 7.nzn temperature and the activity of enzymes such as lw4 9vpkln/bt 7 .z2zzjipase?

1.Sketch a graph to show how increasing conce9hjesegjjp/)ys/ju.f6 +2 i*kl f q8sntrations of substrate affect enzyme act8 gfqsh*9y/ /2esj jksfi6uejlj +).pivity.
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 out k0pssn8usl.4kckj)p o,f9 r,qb 0vb7lining the Calvin cycle is ss0 kp7 nko4ljsvb )q,b8u,.f p 0sckr9hown below.

The image below shows the catalytic site of an enzyme. The substrjd mt2;9g5 kkk3bu vq,ate is shown in black and is bound to the acti kk 5jmk;,quvbg9dt32ve 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 catalysed7qz.qnj +5o br tzqh08 metabolic pathways shown below? Letters representz zn 0+rq5o7. bqqtj8h various products of individual reactions.

  Which of the following describes the role of inhibitors in enzymejhl +y(1*c30g .xtg- lf wskzw-catalysed reaclgs t-gh10w zk. *wly(c3xf+j tions?

  Which of the following correctly describes photosy2 b45- aydhhyhnthesis or respiration?

Many enzymatic reactions 9 1cn cn4 k9glj06u.gt0uawdahappen as pathways involving multiple steps and multiple enzymes. lg6 .ng0w0ctj99cdka 4uuna 1

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

  Which of the following best describes the inhibitord*2j v5 1(pgynygr-mq in the image below?

  Which of the following statements are true regarding regulation by end-productj+sq2 hw/fgn6c /o0jf inhibitf/6no+ gh wc0qfj /s2jion?
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 enzym c;iooojsf9som9qodnm: +3.23lb /c v e. The darkened strucf c9o3qo2;c+o mo:o9dm ssi nj3l.bv /ture in black 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 temperatu628m2iy+4 l dgawh7oak nu az+re on the activi l2dom6h+yawu7zn i8 + 4a2kagty of 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 stagp:3 .j;.bjf (npmvxjubow 9-tements describes how enzymes interact with substrates to catalyze reac:.bppm.jj3 ;b v jgfu x9no-w(tions?
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 enzymncmk .ah(5l)7 x6 iqyye catalysed reactions can be measured.

  How does denaturation chan0m yu f2v3nbx4ge the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statementqmq2i;t-nlzr7 -0a trs are truelt z --20n7 aqm;qirrt?
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 characteristicc2w /0sqai1 jp that separates mammals or endotherms from ectotherms that have fluctuwc/ is1p0 ja2qating body temperatures?

  A metabolic pathway that converts threonine to the end-producl+g6sl q0s)jl/i*rnae sifw 2 jw58 x7t isoleucine consists of0* x f57l/e 2 sl8 agniij6wl)+swqrsj five reactions. Threonine 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 ei k4o+y buuo2a (5igy)i;y u5rnzymatic reaction. What is oir +ui )5yya25oi u(;y4k gbouccurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrgm :;3,lbk xbuate concentration on an enzymatic reaction. What could be tb,lu m:g3 xb;khe independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine tonbh (owe2m( r0un7mo,:4bpa ,nwrx :c 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 mhc2v)w 0 za- qj2x6xyuatrix and its activity was compared with that of a free enzyme 2wxz cyu-vjhq2 xa )06in 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 easily denatured. Which of the following ildxk/ec0wczrep0i -9 :5ah *q p6*pifs the best way to keep enzymes active for a lone5wcd 0*zhkpie- xpp:l/0rf qia c6 *9ger period of time?

  Which of the following describes some types of extracellulle gn,w 4nwsdq614ou3:0 hdkfar enzymes?

  The enzyme pepsin hydr th)/pnv1s -jmrs/9 hgolyses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentr -vsjh)s/t1pmn/ g r9hation 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 increy-6pw.mw -pzqx xk-g /8rzsx-asing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reac.wxxpp/ykw6z 8m-xsrz-q g --tion, 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 student cut a turnip ro zg3 mt7n9adswfo(v3; ot 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 homogenate was filtered and the liquid extract was storeddf3w93av;gzt7 s(m o n 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. t;z yz710ywowInhibitors to the enzyme HMG- CoA reductase can lower the production of ch;0zyyt1wow z7olesterol.


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 in deqof1 v8qk..d gnaturation?
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 investigatiqmjs( sia c yu.*t2ko9b 9de2l7d4o3gng metabolic reactions in the classroom and were given an experiment which demonstratedl93sqy*2 uidgsm9cad e4.o7t2 k j(bo 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 effi p0fl8y:ghjep3.5nf1 rs cro9ciency of lactase activity is tested. Which is an appropriate depesy 0fr38p cfn1.r9pjho :lg5endent variable for this experiment?

  A study has been conducted onv m1i(2gy2lu p the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may v(l2yui2 mg p1potentially 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 f dgfs33st5vp3 or treating patients with malaria. Describe how anti-malarial drugs are bedf33 tps5s3 vging 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 af3;.q8m,wyx y g dy/cllfects the rate of reaction /yg,mllw y8q.c;d xy3.
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 metabofdz-u 839ttzq lic reactions. Which typz8ftu z9dq3t -e(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reacti1ki ,egmz 05/c+pbmo lons can be measured. km5,g1 i0zmp+ol/c be
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, gi/5fw5s8 6jgv6x1wdfhwe)tj 8 wg0fo aven onex)jswh0/wvatd6je8 6o8f55f w 1ggwf 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.