Which of the following macromolecules describ xknzd1e4 ))t .14a e/ksqdr(pojo2nge a typical enzyme?

  What type of reaction is phoj34fb8a3j e.*7xm g vadwnl+z tosynthesis?

  What is the substrate forfbq i9.(n bmfpb*)uv - the enzyme lactase?

  Which of the following stages of cellular respiration ta31p e6h m k./jzemsj-lkes place in the cytoplasm?kjz6 pl h-j/ m.3em1se

  Which of the following would ny o9cj(.wq pd: 3oms),gq.imc ot be useful in determining the rate of an enzyme-catalyzed rea.w .j3ooqpq y9dc imms) (,:gcction?

  Which of the following processes may beg:xw 2l.2kor:ing nj 4kp 1ei6 described as catabolism?

  Which of the following statements is best depicted by the figure bel-msy8z*kq 3ez ow?

  Which statement about enzymes is .sp )o2jixy+f not true?

  Which of the following graphs best illustrates the relationship between te 4hs;oup2e qebp/ (7bwjj/b+rmperature and the activity of enzymes such as l qs/4 2(;ohr7jpbbuwe/b+ epj ipase?

1.Sketch a graph to show how increasing concentrations of substrate aff+cydr5im 3rk9 tr) 3viect enzyme activvc rmd y 9i)3kt+3i5rrity.
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 outlininy7e oub5(-2 t zhti/hhg the C2(it5zt 7e b/hyoh-u halvin cycle is shown below.

The image below shows the catalytic site of an enzro2o*f.ei,x7jp / ukbyme. The substrate is shown in black and is bo 2k,/.* pjreu xiobf7ound 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 metabtw w ,krgji,9k cfd-z,wn.d92 olic pathways shown belo d9wjik - wwn2c9d,,f.zrk,gt w? Letters represent various products of individual reactions.

  Which of the following desc,7j(xo y2fig tribes the role of inhibitors in enzyme-catalysed reactti yxo,2(g f7jions?

  Which of the following correctl ).mn9b(-zzv6vpoq qjy describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple stemjrhcf h.l l/gk nld71a ;ip,k4b5 ;.7nvcn3xps and multiple .1vl7xn;m cgkr ,hnc;p3fj l n la745hki.db/enzymes.

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

  Which of the following best describes the inhibitor in the imaged:y6azd51zau2ytk l/ 5t s fh. below?

  Which of the followinmn8p7z*f isgd e5 khl*at7,8dg statements are true regarding regulation by end-product inhibition?,8 z 5h7gf kl p*t*niad7d8sme
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 lyzp0l15aa2s .zqrwb6 o sozyme enzyme. The darkened structure in black is the surzo5s26.pa lzqw0 a 1bbstrate 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 study the effect of temperatuxxxmq 9st95w7 re on the activity of the enzy 9mxx7w t9q5sxme 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 followinfe)hkm h843l6a 6dr:ji3f zoag statements describes how enzymes interact with substrates to catalhj36 orha)8 lzfdm3 kfa 46i:eyze 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 reactiua;-/ hl8zm :tg2 akzsons can be measured.

  How does denaturation change the properties of an enzr3,kxge6 utm)rq k31hyme?

  Enzymes play a role in catalysing rm6dwrv5nqhjt92e vh.* twm9 6eactions. Which of the following statements are trwmh 5.rwhnj*vttm d69 92q 6evue?
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 ectotherms biu 3,hx+dq2ythat have fluctuating body tempera i2qdb +3huxy,tures?

  A metabolic pathway that conveh lwng4vvbh3 1noemsrl+0*06rts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermedia6o elbv3sr1+*0n vwhnh0lm g4 te 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:n pwnr xkk15atcd 4, ra1d*u3 of an enzymatic reaction. What is occurring during the ph:xndna 3 *rr,ku 1wpt14 c5adkase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentr:9e n0oia /mak7 nj4h)w sd4buation on an enzymatic reaction. What could be the independent ae:mn)u jh4/a70w4kb i9naodsnd dependent variables in this experiment?

  The diagram shows the pathway that converts threonin*/ f/1dg dwlh n* gyzshn17qi2e to isoleucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobilizeds8a9k2jdpeq4mb 3x 54yl g m6g on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activite kq6l5mysj4d92x3p mgb4ga8 y (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 2u(ven/jaqu)t ny8yi;, p3mx following is the best way to mni p u/x8;,u)qvae(t3yj2 yn keep enzymes active for a longer period of time?

  Which of the following describes some types of extracellu.*me lubpb(*o)n wjd 4lar enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomalj8fa*tdxv2 .r;ifl) ch. A study was carried out to determine the effect of increasing substrate concentration on enzym jlvrtxfd ; i.l28*fa)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.awj4nq 4hrn;8tm .ipw 7bk3k70xs y b 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 the reactions. The curve marked A coincides with the activity of the enzyme wiys0mbjr p.bx k73a;w 8inqw7t 4hn.k4 th 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 smallug51y 5fpd,fv1 - xaen 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 andfxy n 5uf5 ,v-deag1p1 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 tt0s s6j srv3zh j3d:r+o the enzyme HMG- CoA reductase can lower the produ 6zjsjt:rr vd33 0+sshction 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 ,r8m1nt,ag wtnrwy/6 robsce+45m-2e 6 zrlsved 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 investig9uw c c4:xp-tsating metabolic reactions in the classroom and were given an experiment which demonstrated the effect of temperature on a catabolic re4cxpc-:wus t9action.
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 ejx 3. wf cw1241tj,gnxv)svbefficiency of lactase activity is tested. Which is an appropriate dependent variable for )2xs4.e31bcjfgnw , 1vvw jxt this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), a5b(oxz v *f36j8afl:da hnbd;cf z))d nalysing the effect of pH, t d 3 b:bn*fdz(clhzd8f; )o56vxfa)jaemperature 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 malari hv,or).6ddjx5rfhwh(-m g r) a. Describe how anti-malarij5( rdhmhr)w -)6ohvr,dxf.gal 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 concentr1vhm0t3p 7k6s5jxi/ izbg q1 jation of an enzyme affects the rate of reactix61 3hij7gi0bjpk vm/ t51szqon.
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 synthesizemb57hs -tbk+ ( aa9zotd through metabolic reactions. Which type(s) of metabolic reactions are condensation- aa+ thbks t9b5o7m(z reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of en7xtw3 rpm3c :pzyme catalyzed reactions can be measuredwpm3x cp3:tr7.
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 extrac;po +exbvxc2 g8z c gg+oqx,vvi)m/.4ellular chemical reactions, given one examplebcmqx8xog.g4 o/2; gpvx v) + c+izve, 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.