Which of the following macromolecul*rlb 9wnuj- 1:n.vl dves describe a typical enzyme?

  What type of reaction iy+bufxr nh;25s photosynthesis?

  What is the substrate for the enzyme l(7p f gg.o:256tt6t klediu itactase?

  Which of the following stages of cellular respirationftaq. (jddxw;j rvadq d m/71rtqz -/r4763da takes place in the cytoplasjm ta/.17jd -a64r ar;d/tvzx7dw f q3(d rqdqm?

  Which of the following would not be useful in determining the rate e*pc;i+uky5jof an enzyme-catalyzed react c5eu*pjki ;y+ion?

  Which of the following processe;d mzb e3ov7/w,.q cik;/qnk3 d96zobvwt)nes may be described as catabolism?

  Which of the following statements is b4qri1r.4 i 2guvtf: kzest depicted by the figure below?

  Which statement about enzymes is notlp:*)d x*bpme true?

  Which of the following graphs (-zh nygf9 q-ygjg;f7h 3vj4 gbest illustrates the relationship between temperature and the avy-hjyz49gg hjf 7-gfq(3g;nctivity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrationomgqzcp-ih2 tu3j/ +q 2ck8j. tv59sls of substrate affect enzyme activivccqk.h u23s-to il+q8mp t9zj5g/j2ty.
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 outwexa )yc587bm lining the Calvin cycl )5me7cxbway8e is shown below.

The image below shows the catalytic site of an enzyme. Thev; lcn-gcv*o7 substrate is shown in black and;7-olv *vn cgc 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 showcy nuqhs1wo2.m+6 3nk.7gyjnn below? Letters represent vqnwjhk y73noug62sym +c .1n.arious products of individual reactions.

  Which of the following describes the role of inhibitors in enbj6yq d8h8 hszu 8 13hbz)f(yjzyme-catalysed reactih zdb(hb q3j88uyzj)y68s fh1ons?

  Which of the following correctly describes photosynthesis or respiration?ai 06uv iyni,*

Many enzymatic reactions happen as pa1odd ;:p 2pg.ltubie/ 5yrmn: thways involving multiple steps and multiple e d1n5e m::oipudty;b.p2/ gr lnzymes.

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

  Which of the following best describes tjg8n 1klflut1 xt8.a +he inhibitor in the image below?

  Which of the following statements are oengp 3s;)l 7dfjnmdg) //q f*true regarding regulation by end-product i dl)jmgq nn*/d;/s7ep3 og f)fnhibition?
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 3xk +7 fm r0xpypy,u-qlysozyme enzyme. The darkened structure in black is the substrate and is bound at the active mq0x3 -ypy fp,ruk7+x site.

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

The equipment below can be used to study-xp)iz kl,tjh8epd. h1 q9ai7 the effect of temperature on the activity of the enzyme amylase..-ipjhpe9)qdxi 1 l, 78 kathz



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 dpi((wztg 1sn rdt k2yz)q)+o:escribes how enzymes interact with substrates to catalyze r 1w(+to yrnpz:zgqk dt)si2)(eactions?
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 reactio ( m(p0:zxjrwm x2l+8b 2pf ocm.s,vuhns can be measured.

  How does denaturation change the 5)0w7pbxc:- kzj:kjj b *t aqvproperties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stawyk8ei),4jstg (z i x;tements are try4j8e;,)gsx( i wtzkiue?
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 ss:g:bwpb- ; eqeparates mammals or endotherms from ectotherms that have fluctuating boe-:qswpg ;bb :dy temperatures?

  A metabolic pathway sa: y0e zmfblxvbh,x 4j:3f)pk(-rk) umt5n; that converts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermedinebt:ua-ph,syvk0f3 x b5 ) )l jxrm:k;f4mz(ate 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 enzymatic :imj-i8q-k l4 n uhq4oreaction. What is occurring during the phase labelled 4kjiq8q- uho-im4:nl section X in the graph?

  An experiment tests the ed.tbq9-v yy*8 g lbp jifvzf)e5 ,;d5cffect of changing substrate concentration on an enzymatic reaction. Wz-5fdq*fc 5 bgv 9yye blvpdi;8t)j. ,hat could be the independent and dependent variables in this experiment?

  The diagram shows the pathway th6i(8o aw0dk lq5kylg **xy ablf0 6do.8:zpulat 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 r-algrel; 29 vits activity was compared with that of a free enzyme erga;9vll- r2 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 of the follf2qw lldr ((cp:g( yd.9j jp9lowing is the best way to keep enzymes active for a longer per9w c2(j:gdp(y(djlr.l lp9qf iod of time?

  Which of the following -;nk4 / mtcyx)kz pmd(describes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins : plk+0b8np ;tsfu cu+to release peptides in the stomach. A study was carried out to determine the e :p tcs+u;l 08+kbnufpffect 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 incr;buxzu+p;s n 84sin 5oeasing 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 marked A coinciden; bn5p us ;xo+zu4s8is 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 /21hcz jn p; baztnr+c, 1 zerm4yw*8fa turnip root into small cubes. They measured approximately 5 ge8 b1 21rhw4 njamzcr,f+*c/yzzp;n t 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 enzyme HMG- Cvx - qq)nb2bpfdo q9 0o.;x( 8b5hxyhxoA reductase can lower the production vy;o5b(.9 qqd bh0h qx )n8poxx-b x2fof 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 invol2tzul-1g 9i mdved 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 )rwy+ e-/uavoin the classroom and were given an experiment whicy +-/eu vr)oawh 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, thg495b .7u ih9c dyngrt qg4.vze effect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for 4qgzn c.45 bigh.d ryg79ut9vthis experiment?

  A study has been conducted on the activity of a specific laguf uv.*c tf+m2f+nl2ctase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be .cgu lf+mf 2 fvu+nt*2used 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 newa:tl1jom*r0 r drugs for treating patients with malaria. Describe how anti-malarial drugs are being dis l0r t:*orja1mcovered 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 concentration of an enzyme affects the rate of rea:h gp5pcte9 s:t3v:navp,8u f8 ekl i)c )sepp:p,t vv3fknec8 l9u8a:t 5gh:ition.
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 /wv8ti2/g,qfmd2rj 45t rylw synthesized through metabolic reactions. Which type(s)yr fw/tid8/5wj 224l, grtqv m 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 measaf8 -ezudq2ql xf80v v(qf;k4ur -q(uvvldfzke8q 2qf; 4x0 8faed.
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 a un l o4* 1wsfotx12pji-(s;rand extracellular chemical reactions, given one exam ja11l iw-x2op*rs fu 4(to;snple 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.