Which of the following macromolecules describe a typical enzymept (sdj.8/ k-x9h7ggtqlo/ tb?

  What type of reaction ikdl3)h 1fzmkxq j,vwve1:m .;)z7vm is photosynthesis?

  What is the substrate y9 cx)si)q/cj l;fl r.ya(mcrrb*j t+2lgb.: for the enzyme lactase?

  Which of the following stages of cellular respiration takes plu prpr;ivgj8g tjmp:: x/ytd)w (+98lace in the cytoplag g; d+vx pr/9p)rtitwmjlp:jy:(8 8usm?

  Which of the following would not be useful in determining the )-la ec 25y1p;ye b uqz3vqz3lrate of an enzyme-caty5l;3y e2qz) 3qzpbau cl ve1-alyzed reaction?

  Which of the following processes may be described a* nby .;0yghx7yasc- as catabolism?

  Which of the following stateme3:dw7 f ze.iub*xgo .m7 wapo1ug:s3ry,) fkr nts is best depicted by the figure below?

  Which statement about enzymes islqb xl;7 3yp8d not true?

  Which of the following graphs best illustrates the relations)ac/ /ekg:ka thip between temperature and /c:)gea/a kkt the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate au6:jub9 22i oc/os izvj5o ke4ffect enzyme activity.io6zie4oo vbu/j2u5j s:k 2c9
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzmyo1g jiaz +-uv0q 71xyme catalysed reactions. A diagram outlining the Calvin cycle is j1uz0a 1gmi+o- yqv7x shown below.

The image below shows the catalyticnt f h*nj)4o*r site of an enzyme. The substrate is shown in black and is bound rhnf )o t*n4j*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 + *+s bmax(kc tlnr--gcatalysed metabolic pathways shown below? Letters represent various proa +(srk-m*n +c tbg-lxducts of individual reactions.

  Which of the following describes the role of inhibitors in enzyme2 la tu2r:8/z n- c4jv/nfyham-catalysed reaction /nhyv4:t2 r8ujmc/nz -2flaas?

  Which of the following correctly describeszm + ,(v)cnf3orsokig w ze4.( photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and yk : xc7zcgl*5multiple c*y5x7k :glzcenzymes.

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

  Which of the following best describes the inhibcuw -70ohk +eritor in the image below?

  Which of the following statements are true regarding regulation by end-pro+ynyz sgss4u1xr ( -5rv3 .jkuql+ o-fduct inhibi f+- ulgyy5uss n3+. k4zor1xsq r-vj(tion?
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 darkm se t*bdh w+6ol2c6m-ened structure in black is the substrate and is bound at twm+l-ed6 o62hm * sbcthe 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 activ)ft0g x9m9rft 8/giyuity of the ex0/fmi9)t8ygtg9u f rnzyme 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 followin2h pto(gt9 u )d:uvlw3g statements describes how enzymes interact with substrates to catalyz :utgutv3w p2l)o(9 dhe 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 cataly.uf, fq4qo2*kotoea 8ggysc2+ s 0sy7sed reactions can be measured.

  How does denaturation ch;. 26orw:hoizusdzak /+9zok ange the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the followfzu mw7,er,y/nd rz7 2ing statements af /7,,euzwnrm7z2dy rre 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 sccglkq45 7cmh:a1x( p f16cxreparates mammals or endotherms from ectotherms that have fluctuating bo:m41 cqa1x5p(c x7c6 hkf rlcgdy temperatures?

  A metabolic pathway that converts threonine to)p8qlgulylx0 u5b3 2q+,u+ kh mrs9 kd the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucinp83uqbmqh kd2x0,y ulrk9 +ll5+) gsu e 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,4ore wtk9l d:l. rt mbt4j*qau:( j1w rate of an enzymatic reaction. What is occ 9b,wtlrl a:j4ru1d.:4(t e twq k*ojmurring during the phase labelled section X in the graph?

  An experiment tests th byayjz)( h i;q j8-,lv0bey-le effect of changing substrate concentration on an enzymatic reabl0i(yahlvy zb 8, -je) qy;j-ction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that s)3m 8xvpckapnj,t/-converts threonine to isoleucine.



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

  Enzyme A (Enz A) was ig0* :a p ;yy/+ijvmsuqmmobilized 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 qy/ gmu*0 +:vspj;i aypH (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 ej dkmwp-2 ewa3xa *d,-asily denatured. Which of the following is the best way to keep enzym,*ka wp md3- w-xdja2ees active for a longer period of time?

  Which of the following-q521gna+snkg; m rq o describes some types of extracellular enzymes?

  The enzyme pepsin hydrolyseshjo98co*g ;/zrbsk 6g proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity a8bgso* 9ohr g c6;kj/zt 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 rq6shz) j0;hh 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 ma) h0rhs6jz;qh rked 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 enzymb: *my *pl/oqu3c ud)ze activity, a student cut a turnip root into small cubes.uc**ul: pdz/3)qmo by 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 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 th3 5+aeelh81v r r8mccvmzw )w,e enzyme HMG- CoA reductase can lower the prodv5a ,8 8chwmcl+verr1zw)em3 uction 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 involveum ggt m((5x:gd 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 classroom andqw;(6ggdtx 87 wzo4 3x;bj yxc were given an experiment which demonstratc48 ;7o6gxdwzj( ;yg bq x3twxed 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 temperaturevm, -hf85ph pf on the efficiency of lactase activity is tested. Which is an appropriate dependent variabp8hfm,p vh f-5le for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analyz qybe6mc 88m)nrii 8x.:bp :ising bi ::p88 ncy mzqixri.em8)6b the 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 find new drugs for treating patients7oj:(m3k5eio zu+jf x with malaria. D5 (7fkju+oimz oxej3: escribe how anti-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 co*de +t.xbbey 5ncentration of an enzyme affects the rate of reactb.e b*5x+etdyion.
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 reactions.s *shcpecj08vq r-42f Whichsq2r ceh-v sp 8c4fj0* type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed req;z8 v,vui4o aa+6zizbc i:5a actions can be measurz6q :z;a84+acu, oiiv5ivabz ed.
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 cheyx ;0+n9h9gnky1i9nn z:z+ pc/ pwvx tmical reactions, given one example of each type of reac1+yv pyz+9hnx :kn/;nzxtpncw i909g tion.
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.