Which of the following macromolecules describe a typical enm+;:lfyv:9 -eb6 wx/m cenknxzyme?

  What type of reaction is50jx5 tk bzkr (t)8 dg56ubg s.gvrd1h photosynthesis?

  What is the substrate for the enzyme lactas8wk j- . qx fm(zb;0r5zbsla9qe?

  Which of the following stages of cel 6jlleb k2enmv p:t a7*z(r5 vhzm+49glular respiration takes place in the cytoplasm? +k4*ztvan9 rp2jl67evmmhg: bzel5(

  Which of the following would not be useful m.)kdi yxhmo6n9u li 9ak1n d::y 1y-65if nbwin determining the rate of an enzyme-catalyzed 6ui9b:knnk a9i1w)x 6:.5f 1d ydly-nyi hommreaction?

  Which of the following processes may be describedis1ac(.d:c+vs/ tugk 4o ,oha as catabolism?

  Which of the following statements is b/v . j5d/k gwt8i9 t euado37)gm.c:mvjgd+btest depicted by the figure below?

  Which statement about enzymes is ndki7 r ;fx0j6rot true?

  Which of the following graphs best illustrates 8y 7f*sjhfmp3:l a7c tthe relationship between temperature and the actyf*cjmf:378a7tsl phivity of enzymes such as lipase?

1.Sketch a graph to showtv i81fq7mc 3okc7csj85 vzk, how increasing concentrations of substrate affect enzyme act tzcmof1q3c7vj7,k 8s 8c 5ikvivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reaction nad9d31v*neh y fe4ouv3z/- qk2n v6oxz6ja;s. A diagram outlining the Calvin cychxqdo/ ajd-n*;oe6v u e33vav1znf n z249y6kle is shown below.

The image below shows t; porx/lu3bv p/d)w )5bl2dyjhe catalytic site of an enzyme. The substrate is shown in black and is x)p3wloy;j / d/ul r25bbdp)vbound 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 t421lj p-g hpsrhe enzyme catalysed metabolic pathways shown below? Letters represent var2ppr4g j s1l-hious products of individual reactions.

  Which of the following describes the role of inhibqt.. d:r5hvdfitors in enzyme-catalysed reaction.5 drv:htfq. ds?

  Which of the followidsc wtw.1fhdc0-44heng correctly describes photosynthesis or respiration?

Many enzymatic reactions happen as patx/7yimd 78uyk2ptn)bv g2lx-hways involving multiple steps and multiple enzymesix7t)vd22py8u yg7/l k- xb nm.

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

  Which of the following best describes the i ju-753twizj snhibitor in the image below?

  Which of the following statement/t lw *ob2)vkks are true regarding regulation by end-product ibko*k/w )tl v2nhibition?
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.c hjkfkc83 *y mp0w0e enzyme. The darkened structure in black is the substrate and is bound at the active site. m 0ehj0wcf38k*p cyk.

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

The equipment below can be used to study 8fyvf -gs ;;fm.4iyiithe effect of temperature on the activity of the enzyme amyl;iff;84mfiy- .svygi ase.



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 descrkna6gqe1o9 a 5ibes how enzymes interact with substratesqeg9naa6 5o1 k to 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 enzyme catalysed re14hf5nd xphce3yd a5 f2acw-3actions can be measured.

  How does denaturation change the properties o 4om,x lf1qi*zsk3th 2f an enzyme?

  Enzymes play a role in catalysing 0-ee/zirso. xf3v gcqz.5s 2 freactions. Which of the following statements are true? 3.0zz2i5vs-feqrocfxs. g /e
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 endotherkg31roqa s i*3 zxy06rrr* o8ims from ectotherms tha 3r6xiiz8y 0q1sor*kao gr3*r t have fluctuating body temperatures?

  A metabolic pathway that convemyii 91g/ j znl-l 7btyu62ou ng-r3*lrts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the lastbn/nmy1zjolg 7*6li3 yu--t9 gl2 rui 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 tjkj (,le x68 ifnq3c6the rate of an enzymatic reaction. What is occurring d8,f qtlji3cx (n 6ej6kuring the phase labelled section X in the graph?

  An experiment tests the effect of changingc )u9bmk2m 6ds substrate concentration on an enzymatic reaction. What could be the umkscm2b)9 6dindependent and dependent variables in this experiment?

  The diagram shows the pathway that conver51p z0 0lxeyauj l)zf33ljqf9ts threonine to isoleucine.



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

  Enzyme A (Enz A) was immobilp ryegp7e9id c7*:-f8c*tm xkized on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying p8mee7id9*f :* 7r -xytcpkpcgH (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 fcj mua zj6;.m/b,bm z*ollowing is the best way to keep enzymes acjm;6 m ucm.a,bzz*/bj tive for a longer period of time?

  Which of the following describes some types of extraxat 7 0 0hhtjq3hjg13 jn6xd7ecellular enzymes?

  The enzyme pepsin hydrolyses proteins to release pe ,o83p bqzn)agptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a b)o pz3g,q an8constant 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 reaoe+t; sxz60rjction 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 reactions. The curve marked A coinzot+ejsr6; x0 cides 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 g.:-l7hcdtpmty, 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 homogenate was h.7mlp dc- :tgfiltered 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 tk.purnqa+5c 1 o the enzyme HMG- CoA reductase can lower the production of cholester+k.rpuc 1 qna5ol.


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 invwj fri 9jbq:v;a1s 43molved 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 reactions in the classrir3xiy4ue6kc *nk/4c oom and were given an experiment which demonstrated the effect of teme ur36cci i4/k4x* knyperature 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 temperay+ yj kxjo8 1,yri4-vfture on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for thi 8+ - fyri1kjxy,ov4jys experiment?

  A study has been conducted on the activity of a specific lactase (Bg10tvnatku w3c(l d)yfc./k2h+) ), analysing tkdfl/cnv)a)uy2h t(. c+t 3 kwhe effect of pH, temperature and 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 j fduw/xa-0i//ye4 sd5enu p9 find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with new techno5yee9d n0j/i/ df-ws4 axp/u ulogies.
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 concentrmg -nz0 gg/0ffation of an enzyme affects the rate of reac0mgfg0/-fg n ztion.
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 reaop + leon7mmv;.6zwh1ctions. Which type(s) of metabolic reactions are cond.1vweo opz+nm6m ;l h7ensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme 6jfm)lr;x q7i catalyzed reactions can be measur7;f 6mj l)xiqred.
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 extracellulko2i3hxx5 qg n+ 3(zbcar chemical reactions, given one example of each type of reacti3gxkb noi5q(h +2 x3czon.
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.