Which of the following macromolecules describe a typicayxd9s h7czq 8+q7 - s;yodn;8qylw+kcl enzyme?

  What type of reaction bddqc1 -nay;j-xz.+qis photosynthesis?

  What is the substrate f1sdkz /ns7+b/oucz - d-ut)oa or the enzyme lactase?

  Which of the following stages of cellular respirat 5co 2- sw k3a.rbu6yuswnhu; p-8j,ybion takes place in the cytopla-,6-sj okcahb3u 2bsw yu n8y;wp. 5ursm?

  Which of the following would not0-fk hi) /mfwy be useful in determining the rate of an enzyme-catalyf 0kfhwmi) /-yzed reaction?

  Which of the following processes may be described as catat90qk(w, ;(..uw bgdd kkrivd bolism?

  Which of the following statements is best depicted by thcioh96pw,v hj;/ br8ho n u;1xe figure below?

  Which statement about enzymed bdt,s2gu/r)w9mc8ehu 0b)x3c ruc:s is not true?

  Which of the followifh ak3 3/b,jftng graphs best illustrates the relationship between temperature and the activity of enzymeskhbf3/3 ,atf j such as lipase?

1.Sketch a graph to show how increasing concentrations of substzna1wi rl--2g rate affect enzymeliz -wr2ag-1n 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 reactions. A diagram outlinip+ 5ax(5pd .l oidp3tdng the Calvin cycle 5p5dp.lt(ipa d3ox d+is shown below.

The image below shows the catalytic site of an enzyme. The substrateq zrcd8+yg-l, is shown in bla+ry8q,zdl-c g ck and is 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 enzyme catalysed metabolic pathways showz:.(wj 1)h3ymv j1f-exjlk ixn bw xkh3 yj ).1mije:-jvx1lfz( elow? Letters represent various products of individual reactions.

  Which of the following describes the role of inh. p *pf*mdja 2dhco(4iibitors in enzyme-catalysed reac *2p4dihmodpfa.c ( *jtions?

  Which of the following correctly describes photosynthesis or rdw 1ej 6ivkxc-w7)3tsixnd g+.v :ob5 espiration?

Many enzymatic reactide7q3bx 9xam) ons happen as pathways involving multiple steps and multiplb q9ma3)xd 7xee enzymes.

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

  Which of the following best describes the inhibit c(;ch .ff*mo.l.r zpyor in the image below?

  Which of the following statements are true regarding regulation by end-product edp( m*j7sa2 linhibiajsdm 7*le2p( 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 darken36)lhxf l csi59h: bired structure in black is the substrate and is bound at the acb: 5hsihrf3xi 6lc9 l)tive site.

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

The equipment below can be used to study the effect of temo.v:1 7xbt0jxcbn ;ftv:*jsa perature on the activity of the enzyme actx *v:.;abox1t j7:vn sj0fbmylase.



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 de:p;q( kahn79)n n piqascribes how enzymes interact with substrates to catn9qnpk q)7:ahin (pa ;alyze 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 reactions can be mea+w ae sr,l ad9*2pc, drswe15qsured.

  How does denaturation change the properties of an4qbgejw )xi( bk *uz:5.vq )di enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statementee f27ygl-bs1s are truefybes1l g27- 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 endother agbm) 6ld37brms from ectotherms that have fluctuating body temperatb d6 rg73)amblures?

  A metabolic pathway that convert qu(3zhv( ilbe,z lmhn-zc)li0 qh6 (9s threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially bez llzi(hh6cqv90 ,b-z3q( )(muinlhy 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 increav u)m nt/+8 fxnoe*z(ysing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled sefez )xn/v( m y+un*o8tction X in the graph?

  An experiment tests thsea+ o2yp0b q6e effect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent vari62ay so p+b0eqables in this experiment?

  The diagram shows thejk/f/d fc -ruf. rf*b) 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 activit e 9w-5cproy ovj:pj6yl80xj 2y was compared with that of a free enzyme in soluty6x w oc:ppyj 9elr2o j5j-8v0ion. 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 thk :btm2rru d*ova5+zm spc1 :;e following is the best way tom os:v1u2zr:5drp ;kac tb+m* keep enzymes active for a longer period of time?

  Which of the following describes some types of extracellultgapc54*krpt r3; hz5 ar enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the st:n9 qb;huum3iomach. A study was carried out to determine the effect of increasing substrate concentrati9q;iunum:b3 h on 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 h2maa zvmv7g wbo +m 0nqizt-p,4n.gdz119 0hwith increasing substrate concentration. Similar concentrations of chemicals A, B, C a2mn+v . zqz,pmo17v-0 4gh nh0w9zdgtbm1aiand 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 sov50e pbong w0 b/gqz*3 p2ff7mall cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip roo 0w7zegob0/qfpbo5ng3p f* 2vt. 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 HMG- CoA bqe ibzg6vy8)/p6k68j krp:s -mr w y3reductase can lower the production of chole6 yk mr3bj p/z 6gy6k :sb)vp-w8rqi8esterol.


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 denatu3)j yz +km..4oyt4h tr xbl,qsration?
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 t: -yn8qlex8 fz x4fsl(he classroom and were given an experiment which demonstrated the effect of temperature on a cata 8 q(xs-4 nllxefy:8fzbolic 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 incrm5mf7h/wkxmozan ,ikv *) 6.reasing temperature on the efficiency of lactase activity is tested. Which is an approp6,ik *57 nh.mmzvmow) kf axr/riate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg1vrv ps8 /ikjg-3p rn:90), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used s3rjpv9:g/kvpin 8 r-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 t 3i6mxlqyfl8:rdv 0+ new drugs for treating patients with malaria. Describe how anti-malarial drugs al :imtyqr f360xdlv8+ re 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 tj+ (:kepbsr s-he concentration of an enzyme affects the rate of reaction.sk- p re(s+bj:
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 synthes)4eru7bw e9 -t,mvxxqized through metabolic reactions. Which type(s) of metabolic reactions are con e,ruve9x4-t) x7mqwbdensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed ; wv+xi-naw4vkr1o 2wreactions can be measured.w1-vr n+i4wax ;w2k vo
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 e(xei, lvs ; 31su85 mcwj,jgdsxtracellular chemical reactions, given one example of each type of reasg5lx,(susv ,;wj i mc1d3 e8jction.
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.