Which of the following macromolecul: j q*fie6)c wn*so2gnes describe a typical enzyme?

  What type of reaction is photosp su0x (bp5cg(ynthesis?

  What is the substrate for the enzyme lactas22cye7e8jk /-xjx rlee?

  Which of the following stages of cellular respiration takes o ,g1i kn6k(p6rw 3ugmplace in the cytoplasm?iwk6p3nkog 16u(, gm r

  Which of the following would not be useful in determinioez3jj mk u*e0cc)5qbw 56 cb*ng the rate of an enzyme-catalyzed reaq05oc u)w j jb3kb5*zec6* ecmction?

  Which of the following processes may , addxoiz)q,-)v6a db be described as catabolism?

  Which of the following statements is bestj+;w8rrgab v b jlk2+3+t juz3 depicted by the figure below?

  Which statement about enzymes is 44r 8tp t.nohky 5-3l tguuqx/not true?

  Which of the following graphs best illustrates the relatiog s gjbayd:+9.br42uynship between temperature and the activ ag bubjy+rg:4dy. 2s9ity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrav03ggaoy.7q utqa63w te affect enzyme aca. wq6y3tu3o7gg q0avtivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed r7f8/ kedh vp-deactions. A diagram outlining vf h78d kd-e/pthe Calvin cycle is shown below.

The image below shows the catalytic site of9ykr a4m v;w dnlco2.1 an enzyme. The substrate is shown in black and is bound to the 2; oc4nl1wav9k m.ydractive 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 tpt3*u y :q (wq,rxy:ngp si:4enzyme catalysed metabolic pathways shown below? Letters represent various products of indivisw,:nrppxi tt :4yqg3 yu(q*:dual reactions.

  Which of the following describes the role of inhibitors k5rn-(s lbc1k0j ge 5kin enzyme-catalysed reactions?klck50gsnkb( 1j-r5e

  Which of the following correctly describes photosynthesis or respiraxw2ei x is2k+b:g4i+ytion?

Many enzymatic reactions happen as pathways involvin4/ayhbm1iig(5 m2e )q: mdoskg8req) g multiple steps and multiple a2m(/gs)8q) hby1 :mkirgeid qome5 4enzymes.

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

  Which of the following best describes the inhibii d4vz)fln g/keu, 0w8n19ljitor in the image below?

  Which of the following statements are true regardinxq fea2y) do,;g regulation by end-product ioyae)2,f;x qdnhibition?
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 5.k+jnc cnsa o* d-seb6j67xq enzyme. The darkened structure in black is the su7oj b.cjx5ske6 *-6qs and+c nbstrate 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 temperatljnm9tp s-wj -i i9gjcf54s *7ure on the activity of the enzyme amylasl9i s*jn-if-jpjtgsmc w4579 e.



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 statembdwf 2(;- x hhay0;lfxepqf. 6ents describes how enzymes interact with substrates h(da6y x-.0;ehpl;wx2 ffbq fto 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 reacjqn :;r6nb h1m*riq2p tions can be measured.

  How does denaturation -+3uu3lz u)tar/s.qnvzsjp 3change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of tq4b4.jq0n vfbzyc x /4he following statements arezn 0qf 4c/.j4 4bvqbyx 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 separates mammr)/oa 81 a)x4usr 5fza,fjhf ials or endotherms from ectotherms that have fluctu)fai f shu)8aafj4 5 zor1r,x/ating body temperatures?

  A metabolic pathway that converts th5rc2 w/fci pju)79my qreonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermedi5cc27 )ijqryumw /pf9ate 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 enzy xop7 j45g1xcoaj8ac7matic reaction. What is occurring during the phase labelled section X in the graphjxaxp7g 548o1ca oc 7j?

  An experiment tests v. i+qabk-p*ethe effect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent va. e -q+bvi*apkriables in this experiment?

  The diagram shows th9 12l1od dhgvve pathway that 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 immobilized on a matrix and its activity was comp*5x o pdnc.4,u ktnvy0r,b4bpared with that of a free enzyme in solution. The graph shows vb5nrut pp,xk,*n4 co4b 0 .ydthe 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 eask3j4a goa0cncm- l56rily denatured. Which of the following is the best way to keep enzymes active fkn3c-4 a5r 0ajm6locgor a longer period of time?

  Which of the following describes some types of extracellular entfidu hk1b8+4iri7 i7 zymes?

  The enzyme pepsin hydrolyses prote qz83d, c5 5*goikbvhqwc (*ulins to release peptides in the stomach. A study was carried out to dbg(w3ulvc*oqz,ckih d5 8 *q5etermine 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 increasr/femvq zzs;0na ,)(/ f8ocfring substrate concentration. Similar concentrations of chemicals A, B, C and D were added independentlyso8mrf; ,nz /f)v/ c (z0arqfe 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 activity, a student cut a turnn8ilg7q f7m z)ip 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 filtered and the liquid extract was stored in a test tube at rooq z7ml8in)f7g m 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. Inhi xgtu* m65joi el4b(mq9q:j9 ubitors to the enzyme HMG- CoA reductase can lower the:e45*txjlbi9u j(uqqmgm6 9o 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+td /8v-abb et are involved 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 and were given acw13+nhdjv + .e1jx9y o 4eqran experiment which demonstrated the effect of1enca43+ j+o.xy9qv rwh1d ej 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 efficiency ppjfg*1e mcjbd: x 1.6of lactase activity is tested. Which is ap:*1c6jfb e 1xgmd. jpn appropriate dependent variable for this experiment?

  A study has been conducted oo h yzpx sibv0gs 5z-;o;7 e8ks5wt:h2n the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentrat2ss zhk;;bgy 8vsw h7:t5i5z o0x-peoion, 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 treaemg2 m 3.oajv(ting patients with malaria. Describe how anti-malarial drugs are being discovered with new technologie(2 agmojm.e v3s.
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 s7.nd,2oe l zakz.c h:of an enzyme affects the rate of reaction. c hkz7ed2s.lz.o,:an
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 syn1 1uu gjiv+40tv/rb1xsuef+v thesized through metabolic reactions. Which type(s) of metabolic reactions are condensation ru iv fj+g 4r0vt v1/u11+xbseueactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the ratjpqvbk-of l2-+/v b7eylpuhit-l8s ,8;-zx ne of enzyme catalyzed reactions can be measured. 2sl /b+,nl8 vy8uep-plh- objvktz- ifx-7q;
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 izewp2(ach7dg8j 6q6 qntracellular and extracellular chemical reactions, given one 7qa(p 8q6gh c 6d2ezjwexample 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.