Which of the following macromolecules d o3amg u. : cm01+1l/pyw 5lmlsljo7izescribe a typical enzyme?

  What type of reaction is photosynthes-l:12 w6;k+bwfcaw ohdw+ky his?

  What is the substratey)w dt+,abzdxlkp)a qf1r+n0fiwu0.9 ( vh q7 for the enzyme lactase?

  Which of the following stages of cellular respiration takes pbp7*h4pxd hl vnn036t 2tyb1slace in the cytoplasm? 6 nn0l 1pts7t3bbh vx2h*py 4d

  Which of the following would not be useful in determi t + 5ltthq(;-hb:tfotning the rate of an enzyme-catalyzed+tqh;b5t f(t- l:tot h reaction?

  Which of the followihc*dvt tje)k jb+0xs5 ;dt1(jng processes may be described as catabolism?

  Which of the following statements is best depicted by the figu 1h9ta-d 1azv1dg ml.qre below?

  Which statement about enzymes is not 9ewi na5xz. -y)k nk;vtrue?

  Which of the following graphs best illustrates the relat-+wmt+pkb at+ 8+aoctionship between temperature and the activit +o+awpa-tktc +bmt8+y of enzymes such as lipase?

1.Sketch a graph to show how incrnu80yezv wp r99pc*j9easing concentrations of substrate affect enzyme activity c9je n8 9ypvrp90uz*w.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme:bdp(;pw lp,h 3yno -k catalysed reactions. A diagram outlining the Calvinh b:dk ;3 -(p,olpywpn cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is uc clfktq;*+4 w:.zkyshown in k*.+w ul4z;yfc cq: tkblack 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 t2/z xcusqv p6gkri cl)ag/gd:*1sf . .he enzyme catalysed metabolic pathways shown below? Letters represent various pro:d * pcq2s)lu.gf aivz/g1rkscx.6g/ ducts of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-c0 x-7oo;fvhpb9v0sz)uuo c7ap w42 ematalysed reacpcv4pu)h7x7m0ew9 o;oub02a - svfzotions?

  Which of the following j( 03tbsm+ucwcorrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving mudkjf//hjysa 5 u..2fx s el-o)ltiple steps and multiple enzyme./y oe.u2k5hs l)as jdx jf-/fs.

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

  Which of the following best describes the inhibitor in tajqw,m,nr ,vl:6gj d pq0 3a4lg pr .-wvar-f)he image below?

  Which of the following statements are true regarding regulation by end-prode w hv4(hi2oy9uct inhibitiohiy 9ve42(ohwn?
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 dn( v1;3 cuynnb/dbm4aarkened structure in black is the substrate and is bound a3/ (;4nybmavbnc1d u nt the active site.

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

The equipment below can4(;smi b8tp+ zbjgaa* be used to study the effect of temperature on the activity ap(zjbmag84 ;s+ bit*of 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 following statements describes how enzymes interact with substrates21r9 wf6 bx:z;;hb yiguqu*a ve,y +lr ty 1rr;,lhqbgiax6 2vw zf: *yu9bue ;+o 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 reactions can be miyl-*cpg 9m 7reasured.

  How does denaturation change the properties of an enzyme?qs+yb+)k , h0hucswkp et12ehan3 f (+

  Enzymes play a role in catalysing reactions. Which of the followinke nq,ow-h5q* wujt0a *f xo*;g statements are u jhn* xe0tq wqk5a*,;ow*-f otrue?
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 ectothk, drbhf/sj13 erms that have fluctuating boh/kd1,3fjrb sdy temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine consi 4nngomo2:/ ue;;z (pgh469zyjk zskkn9x:bpsts of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine gukxo;9sk/z4npk j g: mz26hz o e94bp n;:y(nby 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 ofuwxg be8h 7f,7z (bl4 zdt :laqpa16n. increasing pH on the rate of an enzymatic reaction. What is occurring bzuaa nw1dfl(6 7l.eb4h7x ,:z8 qgtpduring the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzymaz ;4mogkda5r fg* 5(pg 7z4ccstic reaction. What could be th7zg 4;5acf4dm pg(zg srk* co5e independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucine. 9v zb uq 8knk 5;ld(daj9gu-n0



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 comp p8 klqf1vz d8,h.zgl6 )bj2yfdgjo3 2ared with that of a free enzyme in solut)d bz2o3jkyh,1l 8g.6fqzlp vgj2f d8ion. 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 following is the be :1dyw -gzfb4tr8(upd q -+vvpst way to keep enzymes active for a longer period of timwrupv:81b-4v pfd(q-y td gz+e?

  Which of the following describe)pwx1(qn3b c* nc, ries some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins g+o mb.vqnr)vn 7i-f- to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperaoq+v v -n -mg)rnbf7i.ture 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 r kgi c l-p0n(28jg)zsrate of reaction of an enzyme with increasing substrate gc)jgzk0 p8n2l-i( sr 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 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 roodky 3y*ut6**ptxj v3s+ttm g(t into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender 6ytp*jdttt m*yx+*u 3(3kgvsto 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 be nmpca i30rq lqs-nh,66()osjlow. Inhibitors to the enzyme HMG- CoA reductase can lowerqjsh(so- 0lm)nai 36rq6p,c n 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 invol.gc crsy,g5)wzyeso3x2 ;* i yved 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 thdx xz)ef+knm;*w.;na e classroom and were given an experimen)n ;kw nx e;am*f+dxz.t which 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 effectc/gtvk4/ ;ha duw cpfz05cy ,l3 q./fv of increasing temperature on the efficiency of lactase activity;w lgc/ch vk4fy.c/z3,5 vf/puqa0td is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specm,wt x16ix fl; xbx k2a18eilw ufe)23ific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentiallyb xxxiw286m3w2latxu)i;1 lf 1kf ,ee 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 pat;snu k2o ck2w3ients with malaria. Describe howk2 snc;ow23uk anti-malarial drugs are 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 the concentration of an enzyme affectn 6;m39ju6j mb ,xk yby4y xy8z(u.jsks the rate of reaction. jmm 9 yj(yy s,8;. yju3xkk6 bubnz46x
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(b :fmz t9ac;n or synthesized through metabolic reactions. Which type(a (: b9;cznfmts) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differer/bqy/co7 z31xxha n 4nt ways the rate of enzyme catalyzed reactions can be measured.ac/zxh3qob47 /ynr 1x
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 cl wvomfah w(t-3. ; p:-wiwnf60o- fpahemical reactions, given one example of each type of reaction. 6ow-.pm(3t -pfh:wawi; aowfl0 v-f n
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.