Which of the following macro1.drhl ode2l7 molecules describe a typical enzyme?

  What type of reaction is photosynthesljn7nl/-7l cnis?

  What is the substrate for the enz b2tsco zw6xhr( sn,0+p*-m,subsky :yme lactase?

  Which of the following stages of cellular respiration takes place iny hkfx(33fm :d the cytopla3xf fky(3dh: msm?

  Which of the following would not be u-03qzu: 1ku6ctvs j hta6 hz2xseful in determining the rate of an enzyme-cataly1jus6t k xuh haqv3c0 -tz:z26zed reaction?

  Which of the following processes may be described vlre a2x.ce:9 8gpab;as catabolism?

  Which of the followintgtzeo;ty; 6inem2++g statements is best depicted by the figure below?

  Which statement about enzymes is not tr3jk1z u3x-ly a5g9a osue?

  Which of the following graphs best illustrates the relationship between temperay0,azum56l wn17xns a ture and the activity of en, 1nwzy la7m u5xn0s6azymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate affuf3dp d 5o7i,)w)rflxect enzyme actid rfu7)wpoxd3,l f)5ivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalq/wivph i 2+ldhkllb t; 4r1-:ysed reactions. A diagram outlining the Calvin cycle is shown belowv-r +i1qkdh:l;lip/b 4hlt 2w.

The image below shows the catalytic site of an enzyme. The substrat/,01dk3-rmbi 4jdb) mmdltjf e is shown in0jd/md jrtm 3 d1fmibk)b-,l4 black 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 hf r5rr8+ v,cvenzyme catalysed metabolic pathways shown below? Letters represent var,v 5rrfvh 8cr+ious products of individual reactions.

  Which of the following des7;sq+fwiczb kj **c-w cribes the role of inhibitors in enzyme-catalysed reactiw 7iksb-c+zc**j ;wqf ons?

  Which of the following correctly desf:hypysr;ej t p:) ucq,5 gm:0cribes photosynthesis or respiration?

Many enzymatic reactions happen as path )cu+n0;nlnn/. zjy ppways involving multiple steps and multiple enzympcn)+.y pnu/nl 0; znjes.

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

  Which of the following bestu5bz a() baq3r6p:egf)y7zf z describes the inhibitor in the image below?

  Which of the following st-xr b)* cfgm2tatements are true regarding regulation by end-product inhibition?tb2*r -cf )mxg
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 darkene.(jmv-t v /dnxknv ,l/d structure in black is the substrate and is bound at the activel vntkn.v / djm-,(x/v site.

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

The equipment below can be used to study the effect of tempera .(uqm0(qx( l hd6rdglture on the activity of d0l .gl(m(( uqhqxrd6the 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 enzymes inter czuw;kju vm,y :49*z2 hk(t/ 1luehdyact with substrates 9 w hd4h/;,jultyk:1uv uck*z em2zy (to 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 reaction1/, ,1v x2spg s( jskn1g 3h)pxozmwyqs can be measured.

  How does denaturation change ttoa w n ln-37q/8 v9 u)*lxpldt4sda84zol e-xhe properties of an enzyme?

  Enzymes play a role in catalysin h8f5y.0v jzhdtk112 7rpskptg reactions. Which of the following statements are t s p.7 yt1k81tjhkrdzhpv025frue?
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 z9ttz,w 8gm dt;*vy xu7rf +i1or endotherms from ectotherms tha9dzt ;+ gtt8i,zx7ym1u*v frwt have fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-prt .dl5iyw.lj6 oduct isoleucine consists of five reactions. Threonine is converted to various .6.wl5tyj di lintermediate 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 th jwl8w-j 6dao whp0)8ge1at jtoe:12l e rate of an enzymatic reaction. What is occurring during the phase labelled section X in the-dl2t1jgwj) ja t61wo eepao:8h0 lw8 graph?

  An experiment tests the effect of chango:/,qa5lw. nff evplrlz37izhsh0 +:ing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables ilz5fhavr:sq.e,:oh / z+lw3f7li n p0n this experiment?

  The diagram shows the pathway that converts threonine to isoleucinysx(b /) 9fc4 sskp3bce.



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 w2;,2mfp sibm eas compared with that of a free enzyme in soim 2; fse2bmp,lution. 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 folrytaw3:4.04opghi- g ngw0-s8t nt lt lowing is the best way to kee0rt -np tw- tg:lw .4gy n4h0i8oa3tsgp enzymes active for a longer period of time?

  Which of the following descr3c7m n8dr oo/bv8, qclibes some types of extracellular enzymes?

  The enzyme pepsin hydrolt -oxtz m3j-r1/ 4x h4idbpxu1yses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a con1b- ir1hpzou4x tt-4jm dx3x /stant 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 reelkuq*)fb0 lw/+op lmh+k8, caction 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 thoc h0 8flq+euwbk ml*+kl,/ p)e 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 sgy 7wix ;zq)i(5/cj xclbyo 40,(efksmall cubes. They measu7qkoj yi()zlcy/5fi;, eg4swxc0x(b red 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 the enzyn qx40+beut+nd29mn x me HMG- CoA reductase can lower the production of cholx4 n+0+9tnubx 2qenmdesterol.


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 denatura1s gcr*sq,ef( tion?
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 werupo0bbvo;2 2 oiwv:sdmo3v8, e given an experiment so pvv m28u,o wbdo0:2ibv3;owhich demonstrated 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 is dg. xts0vhb6 s7 o)pt/vtu(:ncreasing temperature on the efficiency of lactasexbh(.ps /0 t gsv:6vto7ut)ds activity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lact;swx( hyyx79g88nwee ase (Bg10), analysing the effect of pH, temperature and glucose co;x(y7eh8 9 sw weyn8xgncentration, 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 wi yki 3px)a8y:7leu( opth malaria. Describe how anti-malarial drugs are being discoverekioa)(8yy7: p plue3xd 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 -;y3d zf8ljxh- qwo s 6bgw:,gthe concentration of an enzyme affects the rate of reactioxb386-:qh;ywjw, ldgzfsg- o n.
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 re0nhf5):iyo y/g-ox s2f4zo o vactions. Which type(s) of metabolic reactions are condensation re2x)o0 4yffy: vozi 5nh-og/ soactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed re,:awge;bgeouqw v u8q*1.zt3actions can be measu g qw;3w1t*a8gueuev.:b o,zq red.
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 extrace 77e dk(opl3hqg,t;qu llular chemical reactions, given one example of each t7,gq klq d;u3t7p(he oype 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.