Which of the following macromolecules describe a typicap 1zu 5asp 6z.t ;ok+xptts-i)l enzyme?

  What type of reaction is photos5uy gylb 1c)x.:k k1enynthesis?

  What is the substrate for t7(f/z gn dzu x8fcy 7(jauwl--he enzyme lactase?

  Which of the following stages of cellular respiration takes place in the cytopb s 7o1e z-80zg,tm1b,gbstfwlaegts,b gs bz1 z t8-bfow71,0msm?

  Which of the following would not be useful in determining the rate of an enzyme+n:ne /+wfrd(. mgvbi -catalyzed refmen (g ./wrdi++vn:baction?

  Which of the following processes may be descr5 -s hendu3o.zibed as catabolism?

  Which of the following statements is4r w) fv; n )fuowg ql)eqnixj,-+2lf( best depicted by the figure below?

  Which statement about enzymes is not true)p9u4vz9oosgn qw ;*v9 7sac j?

  Which of the following graphs best illustrates e fcx8c0eua-.4zkshl);zzn8 the relationship between temperature and the activity of xh;8u kes )lecz0c4f-8n .z azenzymes such as lipase?

1.Sketch a graph to show how increasing concentrdd0g:1ox l ei:ations of substrate affect enzyme activxged0 dl:o:1i ity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a se-*m(ceg2ei 2fv kas9p ries of enzyme catalysed reactions. A diagram outlining the Calvin cycle eg vm22i*ea f-sp(9kcis shown below.

The image below shows the catalytic site of an enzym.b gcfuv;7 4)b7us/nqv;znf se. The substrate is shown in black and in 7v.q u;;u/) f4gnvs7bsbfczs 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 z)i q7 aiw. hloxx8xupbz ny4w* (/l1l7:. tjvenzyme catalysed metabolic pathways shown below? Letters represent various products of individual reactionb.q w z(7vz8y p.ltl xa1*74oij u:hx )ixwln/s.

  Which of the following descrx4z p/ pvxl89ribes the role of inhibitors in enzyme-catalysed reactionsrvz px9x84/l p?

  Which of the following correctly describes photosynthesis or respiration?hh/ 3sfcw -be wm*dk t83xa1t-i3c9na

Many enzymatic reactions happen as pathways involving mq/lw g bwp8ts7 9w;2yzultiple steps and multiple enzymesp/ s8 z2lbqyw9t7w gw;.

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

  Which of the following best describes th ni0 d763)lxq +lujryce inhibitor in the image below?

  Which of the following state.mwuo 6c9b4ui wzsw-1ments are true regarding regulation by end-product icwb1msuu9w-zi64w o . nhibition?
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 .3tm cd4td/. frg,jsxthe lysozyme enzyme. The darkened structure in black is the sub.d tjsm ,c/34g.ftx drstrate 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 ;zqyfd 0rnyr3) mefu +;l f29ak,pry5activity of the enzyme amylalayy ;9ff p) fy+rrd3 zr;m25nuke q,0se.



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 substra pn9; d ylm43dccb3y7actf z;-tes to3d cmf y4a7;nt3ly-; bzcp c9d 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 catalysx5ex.zzs, kj+hto+ r4 ed reactions can be measured.

  How does denaturation change the properties of an enzymu*+zj zhsh/i/q 1 +t;+ojauemma8x 1v e?

  Enzymes play a role in catalysing reactions. Which of the following s / g;nsk0bh+zatatements are true ;hz+/bnks a0g?
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 ectotherms r kqhs*v*/x mi 7w (9hz1u-aj6k2mnko that have fluctuating body temperatures?v1-no6**ir(waqzskk/ hm m u279h k jx

  A metabolic pathway that converts threonine to the en3.wp07/b oopz/sf)o h gfl z.vd-product isoleucine consists of five reactionp zwf./7fo 0ovh /.)lgpzbs3o s. 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 p1 b,04qlhijm aw3xlyr/h8t/ vH on the rate of an enzymatic reaction. What is occurring during the phase laqaxl//t ry13h ,0vj mbw48 ilhbelled section X in the graph?

  An experiment tests the effect of changing substrate concentration ongpy 4mvi .8d+l an enzymatic reaction. What could be the independent and dependent variables in this experimm4ld vgpi.+ y8ent?

  The diagram shows the pathway that converts threonine to isole8m,708r gxtalvpn+ x2er8:sf0 hjr s xk ta,;eucine.



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

  Enzyme A (Enz A) was immobilized on ;lgtfnw s/* +ta matrix and its activity was compared with that of a free enzy/ngtwft* + ls;me in 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 ib;oqh-d-1bi sw,)*m)qdubb z s the best way to keep enzymes activeq bubm--,)os bw1b)zq id d;*h for a longer period of time?

  Which of the following descrir 4hr1bi frj72bes some types of extracellular enzymes?

  The enzyme pepsin hydrolypn ao; org* ;*n um-vz2-h,bwyses proteins to release peptides in the stomach. A study was carried out to determine the effect of incre;-w h* ruyn;*om -n,oag z2pvbasing 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 showz36blr ,/hugxs the rate of 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 reactions. The curve marked A coincides with the activity of the enzyme with no inhb3,zh/r6gu xlibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a turnip root intps* 3 0kvxs6wo7rh/xvo small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blens7xx*po6 vwr vks3h/0der 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 aj52*dr emj -h5 xxq/kis shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the produc*qxx2d / m5ahr-j ekj5tion 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 inv z) q)8c.p5,u:cztkosv 4xq jcolved 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 iq: mpst , p)m;,ip5euen the classroom and were given an experiment which demonstrated themms ti e5;,:,ueq)p pp 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 ef6:hyth. lo vu; ij(wd2fect of increasing temperature on the efficiency of lactase activity is testeith.o6;2dv j( yh uw:ld. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on thw*+4(d .fnbqoq y,yr s7a5f sae activity of a specific lactase (Bg10), analysing the efafy .nb+q5s*, 4r wsyaqf( do7fect 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 find new drugs for treating patients witelikva9ib/gux fv017g89( e q* 5nemmh malaria. Describe how anti-malarial diq9ge9n*1m iu( 8ab xvf5/ek m0el 7vgrugs 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 8r;-uhwwdll . f.0q dv4vnbixi; :ru *the rate of reactio8 lq- ;vdxbnr0ri4wwf .iu l:*. ;vduhn.
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 reg lyxuk*z*yvm :d;3v (actions. Which type(s) of metaboliz*d3xymkgl* vu (y;v: c reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions -iifn).t(6qz.gdy.9 ,ug h scpdk9 nlcan be measu hd(9.,u qf.)di cigpzn 9-g .sylkt6nred.
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 reactionsk;us g;8wgl7 amu tp30, given one example of eachps wm a7ul8;0kt;gu3g 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.