Which of the following macromolecules describe a typical e 3sy1fpdc4l81nar,bi8gto 9bnzyme?

  What type of reaction is photosynthh38 4jsp2tp:l n jw(fuesis?

  What is the substrate for the enzyme lact6b)xhcb v/ksv*gp; )ease?

  Which of the following stagiuo-p)8s g8 2eg6hidjes of cellular respiration takes place in the cytoplasg e8o28-pigisdu6)jh m?

  Which of the following would not be useful in determining the rate ofqc :5 aqeh4 x2fcd:.ha an enzyme-catalyzed reaacdaehx q5: hf4: .cq2ction?

  Which of the followinxh86d,a ic us2g processes may be described as catabolism?

  Which of the following statements is bestkpe 2b8xnk7 3u depicted by the figure below?

  Which statement about enzymes is not true?y1t(hbys mun-rj9 i;9n 7m fg+

  Which of the following graphs best illustrates the r3vustxch+.vg8p zl2qk34 x2o elationship between temperature and x+ .g2phv3 sc8u3xqlzok2 4 vtthe activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentraz.a lqjp3w2 8etions of substrate affect enzyme activity. j23e8lpw qa .z
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a sereit4s 6v;6y s -r4ienfies of enzyme catalysed reactions. A diagram outlining the Calvin cycfen4 ; e 6ist-sriyv46le is shown below.

The image below shows the cata bl,ouh0w dxr3wy.55ardn(, alytic site of an enzyme. The substrate is shown in black and is bound to the activ(5way3d rdwlx a u.,hnob0 r5,e 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 z1je1*:xu1mf5pqy6+ja og cv of the enzyme catalysed metabolic pathways shown below? Letters represent various products of individual reactions. 5m j1 vo11pzq6*x +ucagj:ef y

  Which of the following describes the role of inhibitors in enzyme-3c( ht 0otzt9fcatalysed react 3c9tft t(h0zoions?

  Which of the following correctly describes pho3 uo 01u;1yuwfinse5rtosynthesis or respiration?

Many enzymatic reactions s2 lfu yjq(20t qefd(4happen as pathways involving multiple steps and multiple e 0t lquej y(dqs2f24(fnzymes.

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

  Which of the following best describes the inhibitor in the ; xmqwb+mzh 91image below?

  Which of the following statements are true regarding regulation by end-product 8bwdhv v(tgag 8.1cd8inhibitiov .w1tb8 cdh( gda88gvn?
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 :jm8(e9e s cjtm)3zxdkw5 ms)of the lysozyme enzyme. The darkened structure in black is the substrate and ezs )5 :jx93mc8w (demj)mkstis 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 temh7huf aw7 j 7/7igoce2perature on the activity of the enzym7ice7f h/a 7hgwo27 jue 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 interact wit u5jgm3-mv.t9sfu v.x h substrates to catalyze r .vx.35m 9jsum-vutf geactions?
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 catal 5y /1m;4u xue/jve/bzh.afls ysed reactions can be measured.

  How does denaturation change the properties of an/g pguq 8t/nx5 (z5dkgu 11sai enzyme?

  Enzymes play a role in catalysing reactions. Which of the folm2 /j: krt;4a;ggqo:qgq;lktlowing statements ar:;k tqko;qtg/g ar4qmg:l; 2je 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 mammals or endotherms from ectother71 qpvl7nyau)ms that have fluctuating body temyvl7 7qp)na1u peratures?

  A metabolic pathway that converts threonine to the end-product isoleucine ue3f(p 7tijkp4-qpt 7consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzym(7fpt kuj4-pepq t7i3es 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 eb8r/v e+d qfhk:n6 5nwnzymatic reaction. What is occurrh q+nwbke6vrf 8 /5d:ning during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration (8fj/cjhwm t qq)emj i :/f;3xon an enzymatic reaction. What could be the independent and dependent variables in thi) e/j h3/fjmtq;:mij8c qx (fws experiment?

  The diagram shows the pathway that converts threonine to i(, w4ihnkvcs0 soleucine.



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 compared with owc0 ;.8r6ya7cns6p onek1i a ll*2knthat of a free enzyme in solu.2akw6nlno*pks 076i;e lycc rno8 a 1tion. 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. Whic ubbu t4)mb/dvfz .dp1h;0*6.uvdmd rh of the following is the best way to keep enzymes a*udmmut/b0 p1f)6; . rdudv bhvb.d4z ctive for a longer period of time?

  Which of the following describes some t 2i(t3 /,1n. kpeolygvi t/hanypes of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to relifw rs9boct)n k: 12r-v sz+d1ease peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzymsiso-d nk vb)1wtc+zr19f r2:e 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 eqc*7fj3x7 42xry8b ry6dbocl nzyme 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 the reactions. The curve mark 4f2od y7j8lbr36ybcqxr 7 *xced 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 activithpc5ak 2utb4m,(j/cutpk . e) y, 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 tj a)up5ehuc(bt k,tcmp4k./2 he 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 HMG5dal;wvzr 1 :vtb/8do - CoA reductase can lowa/d dvo ;1tl8wv5: zbrer the 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 are involvamzj,gshzy2 h1:c+sp4v 9s:9f+ he eued 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 wer9lvyx73:le sve given an experiment whichs 3v9lel7 yx:v 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 inha,t ;: bi-hr3ar)xq zcreasing temperature on the efficiency of lactase activity is tet i)ah, rz;bq- ax:rh3sted. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activi q1-tmho/ffs25h86hu* *rm hn y idnp5ty of a specific lactase (Bg10), analysing the effect of pH, temperatur *s85d6fp-uh ho/ hn*m y1hfr 25ntimqe and 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 treating patients with malai-7k-(in( oosc /z2vkbsz n1lria. Describe how anti-malarial drugs are being discovered with new techko7 lz2cv skbo(/n i-s i1z-(nnologies.
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 of an enzyme affects the rate of re qe.m g)g0by*8 bbtvb8acty be .b)g8vb0bm8 gt*qion.
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 reacti s0of6 w8exy 0;dboss.ons. Which typwx 60fo e0 ;dbsysso8.e(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be gptsy) xq(ov3l+ ;dw: measured. )+spqdv x;3twlyo( :g
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 reactiony kf11 k0dxubs q165dns, given one example of each type of readk1f sy x06q5udk11b nction.
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.