Which of the following macromolecules deseudgotl/ 2g-9cribe a typical enzyme?

  What type of reaction is photosynthe+1cu h1q :xkcxsis?

  What is the substrate bk7xtj(hft58u nh,r+ for the enzyme lactase?

  Which of the following stages of cellular respiration takes pr7+ dt e7eg/rfom(uu- w6k;w kj 5k54 wv5wxcdlace in the cytoplasm?;4e+mrufwkw ru-w vd7( k6d5 /j xkt755ogew c

  Which of the followinxy6 y r9;atf* ak,lt(g gm6sh9g would not be useful in determining the rate of an enzyme-catalyzed reaction?krm(tx tf6ah*9g;l9 ga6 ys,y

  Which of the following processes may be described as catabol,dqvx taldt6 a86 5v-aism?

  Which of the following statements is best depi ,kf6dtb75nl,s fk.o mcted by the figure below?

  Which statement about enzyme5;r7 uc we5yqhs is not true?

  Which of the following graphs best illustem9 ab+qvq2n 4rates the relationship between temperature and 9qqab+2 n me4vthe activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substr4p* c kgownby kve-8/b.aa.-e ate affect enzyme activity. knoy4b.w.- ae apc-8kbv*/e g
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme cataly06vh/jac08hku *i elk50 h-q atc5qbksed reactions. A diagram outlining the Calvin cycle 5hqt-00k 8 l*vhk5aj0i ea/ubc 6cqhkis shown below.

The image below shows the catalytic site of an enzyme. Tc2z zir79ddg1y(6dtoj0 i 6cb he substrate is shown in black and is bound to the actiiz 0d bd(i7odc rt12c6yjzg 69ve 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 catalysedz+ *w:eeb86 od49orj)ch:qjsbjf o6b metabolic pathways shown below? Letters represent6 oj:sojfo:d 98eb c4j b+h)6rqwbz*e various products of individual reactions.

  Which of the following describes the role of inhibitors in enzymw0+crq) xo 6wr.(e,k. bizmcze-catalysed reactions+qce r,xb 0kowic..r)6zm wz (?

  Which of the following (8 jpfpoo k5wp(i4y2c+b y a/qcorrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and(2lcvbsfm8ja )4n fe5 multiple enzyme58sfjvc)n 4ml2 ea(bfs.

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

  Which of the followioh(l/ q/o:coz (2oao;ncq f7 ing best describes the inhibitor in the image below?

  Which of the following statements are true regarding reg -19qaa q,8tjm0tsykhsur*t5 ulation by end-product inhit980 r- *hjsy1a,ma5sttuqq k bition?
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 +7h,,ytj*zse )f27cn t nvnvlstructure of the lysozyme enzyme. The darkened str7nhf7e t2tnn*,zls ,) jyv+cvucture in black is the substrate 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 ut/ y iq)pa3:-kabk1jstudy the effect of temperature on the activity oytq-iab3)/ j1:kap k uf the 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 followin5m+ g/9je lsqivsth-x 248iifg statements describes how enzymes interact with substrates to catalyze reactiol5jssxvhqi48 fg i2t / -+ie9mns?
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 catas +tcvhi(wa3o,0 -oqh lysed reactions can be measured.

  How does denaturation change the properties of an enzymg z+.he9 jqnf )nvl9g3e?

  Enzymes play a role in catalysing reactions. Which of the follow1bdd u:l*z pw+ing statements awp:dlb * dz+u1re 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 characterispu u eqf 8xo-w8nw9e4w)68snd2+le hetic that separates mammals or endotherms from ectotherms that have fluctuatinf2h8e9+dee ww uns-86 qpe4xwnuo)l 8 g body temperatures?

  A metabolic pathway that converts threonibv 7mz8du)z :fne to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is du mb8fv7)zz: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 enzymatic q a(/ pp5d/pboreaction. Whbo /q(dp /5papat is occurring during the phase labelled section X in the graph?

  An experiment tests the effgd6zz2ta iz 4m,7i l)aect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent tazzg)im7z,aid6 2l4 variables in this experiment?

  The diagram shows the pathway that convertsb* vqt33 qwk c1u,7pe8oju fq8 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 :hb . r9m/vhte3/kzwq a matrix and its activity was compared with that of a fq 9z.emv h /thr:kw/3bree enzyme in solution. 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 o wk-4tr )4l+yioj;qkv1vkq;v f the following is the best way to keep enzymes active for a longer periodyo-)qkk + vtk4qjir;vv4 wl;1 of time?

  Which of the following describes some types of exp: fe;h*rndkt)0uzsb5k /uda yt7.3f tracellular enzymes?

  The enzyme pepsin hydr xhh.nwe,e2 ly wd9owkjp3;++olyses proteins to release peptides in the stomach. A studyh+w e+.ylxwhk n;32po9,edjw was carried out to determine 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 increasing subs 7hv14)3auge fsran w;d7l7 ymtrate concentration. Similar concentrations of chemicals A, B, ug7lm4 yr71aw )dh7ev fs;na3 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,54brk :brhlm , a student cut a turnip 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 extlhbrm 5 4k:,brract 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 HM0(g+ xzs5be5yuibi g 9G- CoA reductase can lower the production of cho+bxi5be usy g9 i0z5(glesterol.


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 dd4,r7j itms9jyri :b/ enaturation?
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 reactioen44 q3 9qi3 :hxhwv8g (aa9 ijnx)havns in the classroom and were given an experiment which demonstrated the effect of temperature o xw ih) an8aj:qhx39qn44ah39i(vegv n 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 efficiency62zl +l;qqb me of lactase activity is tested. Which is an appropriate l;qb2em+qz l6 dependent variable for this experiment?

  A study has been conducted on the activity of a spece .cosy+hxr 8.ific lactase (Bg10), analysing the effect of pH, temperature a h. yrxoec.8+snd 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 tre2 +o(e-wk cje+ mwtrd.;i(3*txp5nnfj p y:pjating patients with malaria. Describe how anti-malarial drugs are being discoverjkxp(iw2eo3 (-w* tp f; d5ej.tycmp njr+:n +ed 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 concen-,tog4a g7aol9cn/ c ttration of an enzyme affects the rate of react97t,t oog4nlca c /ga-ion.
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 syu6nnbt r1lflme+ 4,.g0o y)q ywwb 4,cnthesized through metabolic reactions. Which type(s) of metabolic reactions are conr cbe l 4tw g1y+,ln0,q4fy.)mu on6bwdensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of efk cydg1dz :6+nzyme catalyzed reactions can be measured. 16:fzk+ y dcgd
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, gi ;ag77 fbf)oczfl-8yx emm,a4 ven onecm 7-o ,4 xzey)8;7fffmg alab example 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.