Which of the following mac+kn.g8 f6sp9dp i uk/iromolecules describe a typical enzyme?

  What type of reaction is phn*pchn:7p dt :otosynthesis?

  What is the substrate for the enf9r3brfw 1k,gozm y /v5 k*9bzzyme lactase?

  Which of the following stages of cellular respiration wkfb o 4sk 9.ao76k zkvo+;8eftakes place in the cytoplaskkob fe;a869sov+ o 7kz4 kwf.m?

  Which of the following would not be useful u crfv) gg/(1p. xfdc;hivrwc:m q;*/in determining the rate of an enzyme-catalyzed reacc/ gu p.cr qx(vcvf:rm;fi1gwh/* );dtion?

  Which of the following processes may aww grzgpz+er+ 64o(7 be described as catabolism?

  Which of the following statements is bete +jzla bx:.xt3mo. 1 w3+wqtst depicted by the figure below?

  Which statement about enzymesu)v9nj8.fd1vl 2v2 jc8 w)trdghj j4k is not true?

  Which of the following grlw+e)zl+77ku qv )bkr aphs best illustrates the relationship between temperature and the activity of enzymes such as lirlekklqb7 u+ vz )w+7)pase?

1.Sketch a graph to show how increasing concentrations of subsqmf*m prrvk,i0g*ap9whfe /x,39ueyc . x 2(itrate affect enzym k xx2yf,.9 r/g* ahviucrf9*pq0p 3,mmi (eewe activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed ren 90(lm3tj9 5wy ez29rhpuvtbactions. A diagram outlining the Calv9mn0 93 2wvp5jt t h(urzyb9lein cycle is shown below.

The image below shows the catald s19i.n /b lzwkv,l nbt*)ey5ytic site of an enzyme. The substrate is shown in black and is bound tyzbvs*lb i /nw . 1tl)d9n5e,ko 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 e9:7.xx2i;tcp*cv*uefv c 7eg:ov s sqnzyme catalysed metabolic pathways shown below? Letters represent c :9svpoef* .tvvxiuqg7;*:xc 7 ce2s various products of individual reactions.

  Which of the following describem cjbqb) w+n:8*pc -cjs the role of inhibitors in enzyme-catalysed reacjbb-jcpcn *c mq8+:)w tions?

  Which of the following correctly describes photosynthesis or respirationa. 5 vk 7ydu;cna.p-dj zfh,k7u,-bd a?

Many enzymatic reactions happen as pathways involving m kh :/rqe1wmu+ultiple steps and multiple enzy1me:q + kwuh/rmes.

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

  Which of the following best describes the inhibitorwm kzq(:)wsj, in the image below?

  Which of the following st9ip s(7qg r.uubu2cw (atements are true regarding regulation by end-product inhibitionp7 gibwu (2ur.9( scuq?
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 9k;4l ,xybzjt cr0r8idqq0h4 enzyme. The darkened structure in black is the substrate and zbilr0 9qxh; q80k 4,jy4trcd 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 temperan.eqh bd/ j8p:ture on the activity of thnd /:8epj. bhqe 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 statements describes how enzyme/2of y25 x+ ren(cjfias interact with substrates to cat yoj5/e2f2 + cfi(rnaxalyze 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 enzysn:r k*k7* npyme catalysed reactions can be measured.

  How does denaturation change the properties of an enzyme?/inebksz9 rdmi0w41 au1mm .x;5.wt q

  Enzymes play a role in8ah ) urcell( hc(es15 catalysing reactions. Which of the following statements are tc(crhuh)5l e sa1 le8(rue?
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 e8nh yu w4:c3wb pa,.nondotherms from ectotherms that have fluctuating boda8 bow:h nuy4n3wpc. ,y temperatures?

  A metabolic pathway that converts threonine to the( 3 3 iisr zy4 3yptqort5p2+j/nyvl)m end-product isoleucine consists of five reactions. Threonine is converted to various intero/z23+nrjp tt risy )vpy34miql3y5 (mediate 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 enzymatyus9 sz6bz.zsw ;( j7wic reaction. What is oc; us s796zsbwz.j zyw(curring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzdx9;;yd 3d o y9fg4zxsymatic reaction. What could be the independent and depende;9;ydofd3dx49 zxys gnt variables in this experiment?

  The diagram shows the pathw )g0aqcst/ sf3ay 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 a0glyn1 *8-, hu snacnah-z8n 0fhk 8dmctivity was compared with that of a free enzyme in solution d*-hgk-0 mulf,cnn8y a8s08hahzn n1. 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 ef6zk(wnbj.zk:il 2z5 *m1jys asily denatured. Which of the following is the best way to keep enzymes active for a longer period of m izfjsjwk(2l6k5.bz1 yzn:*time?

  Which of the following describes some types of extracellular b19o(zulxo )1me3 dmnbrlj lg44w*l8 enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A r.l pha/ y( (ri azk0zdos8hll3-e t);study was carried out to determine the effect of incr;kpar ) z(( zy8/0tohde -r 3aslhli.leasing 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 increasing substratl3wf9io, ag/te concif ,la9o/w3 gtentration. 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 inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a turnip root into small cubes.j61 wdr os2zs*n kohn48e/1u m They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to 4/uo1d1 8r hnsjnkw*m zos2e6homogenize 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 the enzyme Hbrvd .f ls-.v/MG- CoA reductase can lower the production of choslbr-d/vf.. v lesterol.


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 denaturation?.o*bquf5 yuwz* bf2.d
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 igjlr 8 7k7oo7nn the classroom and were given an experiment which demonstrated the eo77 ln7j8g kroffect 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 effes0,ffzq x gn /g2rt9p2ct of increasing temperature on the efficiency of lactase acg0sz r2x2f qt9np,fg /tivity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activitycrw;zou 6 tlb( vzn;o5.xb+ 2wkp /hi3 of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactah pt6r( .zblik v5uo w/zo2x ;cn3;+wbse 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 with mala0px8b0/.l m ljfyv5nyria. Describe how ay 0x8bj m flpnylv0/5.nti-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 +5 cbalvh1gw:rexf 9 f)p)si- the concentration of an enzyme affects the rate of reactig l :bsv -ap+)we f)cx1f5r9ihon.
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 f2h uiig:wb7 b0pz2km.( b cc-2ml2hosynthesized through metabolic reactions. Whichkh 20z(bu bhf2iwm2.lg- pcb7omi :c2 type(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the r4gr) t-ute8utbibr7-b xa+o bw + -eo/ate of enzyme catalyzed reactions can be measured. ttaxr7 i-u)8o+o b4-rbtg bbew/-+ue
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, givenu gyuph62r-j7 one example of each tj-pgu2r y76 uhype 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.