Which of the followilr ex1 h hty)sy9+dx*o/,u+jwng macromolecules describe a typical enzyme?

  What type of reaction is pkzgjko jh.425 hotosynthesis?

  What is the substrate fo8z/+f2qjizm/ *vaiywm 7; utqr the enzyme lactase?

  Which of the following stages of cellular respiration takes /etcr8vxc2 dun5h ;o,place in the cytoplat8,v/ohe nu2 rc5;c dxsm?

  Which of the following would not be useful in determining the rat x7ndmfrnrr8ct0zo; l + /f2y3e of an enzyme-catalyzed reactt8z mrd+2;/r ny r037nfcflxo ion?

  Which of the following processes may be described as cah2yw:7tjf m:4r jh be9tabolism?

  Which of the following statements is best depictedy4r ,-lzr 0jur by the figure below?

  Which statement about enzyhu,wz/ i41v r :)wheqfmes is not true?

  Which of the following graphs best illustrates the relationshipiishm w ;d13hl77 crj3 between temperature and t3hc; r3i 1smdw7lhi j7he activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate a- :vud ig4++latx:(s-dtyp3xph4 nvfffect enzyme acyh3 :vn l(-v pxd s++f4xt :ud-4igtpativity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series o l9f 3 mv 5a)tne(4aozj7nswg8f enzyme catalysed reactions. A diagram outlining the Calvin cycle if9e74ja3n8)gtlv z aonw 5m(ss shown below.

The image below shows the catalytic site ofg)2cs qw 96d(xk ly3ne:oky6o an enzyme. The substrate is shown in black and is bou6go3sycd lekow (xy: q6 k92n)nd 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 enzyp3eub.0 qhlzz42v/aq db4 -usme catalysed metabolic pathways shown below? Letters represent various produ 4q/duz4uqe 3svlbbzha0. 2- pcts of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysenz6o7as4dv(x (,zlck d reactio(az4kn,l v 6(xzcsod7ns?

  Which of the following correctly t4:ubg4:j n wkdescribes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involv/2 wbk km;s+djing multiple steps and multiple enzymes.+jwdk /b kms;2

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

  Which of the following best describes the inhibitor in ;(m2xv j8x4(qrf8aamcg*0uj)ycy lp the image below?

  Which of the following statements are true regardinolu 58f8loi4 ag regulation by end-product inhibitiool 84ol58u iafn?
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 structubyv dywwti6xosq 1cy1ca/5 +9zy: .j*re of the lysozyme enzyme. The darkened structure in black is the substrate a1x: /6 t1j5ys ib9zvwqo*acywy. y cd+nd 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 temperature b f03d6dbdb5yon the activity of the 6 bf05ydb3bd denzyme 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 st +us zt3-gug2ogvr 7h0atements describes how enzymes interact with substrates to g2s u+7tgo0hzur gv3- 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 catalycr/wxi;xy17 iun n: dgt (7g3xsed reactions can be measured.

  How does denaturation change the properties of an endq;./ kfkcm ,tzyme?

  Enzymes play a role in catalysing reactions. Which ofg 8f pfv5tq8+w,m;mz c the following statements are true?cf8;g+ zq v8 ,w5tmpmf
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 fw;; c gzph2nk4rom ectotherms that h;nhw cg kp24z;ave fluctuating body temperatures?

  A metabolic pathway that converts threonine toj:5 h0z0onhtk the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes t knh:z00ho 5jbefore 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 theq b. ukdk rpb*ogh,*;1 rate of an enzymatic reaction. What is occurring during the phase labelled section X in the g1kprg,ko*;b q duh*.b raph?

  An experiment tests 7ze)sr -wxl8tcq q0 6fthe effect of changing substrate concentration on an enzymatic reaction. What could be the independent and depe78tlfrws z x)cq 06-qendent variables in this experiment?

  The diagram shows the pathway that converts t 14)q*qljm:a(moo ufwhreonine 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 its t0g3mgb/1i+ cu2ldxa activity was compared with that of a free enzyme in solution. The graph s3it2mgblud gx 0ca 1/+hows 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 folytp- 2fw83 cbr4so jp,lowing is the best way to keep enzymes active for a longer pers3j- ,2 p otpb4c8rfywiod of time?

  Which of the following describes some types of q5k1iq 31 agblextracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomachsec30 6r1amo)r9 cx pr. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity p6ec )9r rc s1r3omax0at 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 withq, 1o87mgm o kddmu)h9 increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monm8k,oom d9q)ugd1 hm7 itored 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 okeqz(h5(y hco8kg69 activity, 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 extract was stored in a test tube at room temperature.6ckok (z9g8 hqe h5oy(


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. Inh4 xn1 dvtvyoddj)/i16 ibitors to the enzyme HMG- CoA reductasnd )x/y61votd1d4 ijve can lower 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 invobzqk c+k;n-r;,nik5 clved 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 were given d pb7o f54a4otan experiment which demao5b f4od 47tponstrated 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 increasing temperature on the efficiency of2(,pz+y mw8w* , tjuml-gucnr lactase activity is tested. Which is an appropriate dependent variable for this experimey w ,m2pzg,uw(m+8jcl untr-* nt?

  A study has been conducted on the activity 1n rz:zm ynb9*z0z-e9owl;onof a specific lactase (Bg10), analysing the effect of pH, temo* onbmyze :9lnw-01; n zzzr9perature 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 withk q+xb.18s; g-nyoexizcxp 88fk6b9r malaria. Describe how antibxnyx f8k . 1iqbxpeo9s +z;-r88kg6c-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 affects the rate of:.olv* ndg.b* -ds:hwd jxw3v react 3v*v- .x *d:nj.wshbo dlwg:dion.
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 metabolrt: wvyq+/ -veic reactions. Which type(s) of metabolic reactions are tywv ve/rq+-: condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rateyjnb;f( 3ihx)m4jdxanz6 9 3a of enzyme catalyzed reactions can be measurefdxn 9y)ijxjam6anb(4 zh3 ;3d.
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 reactiov)0uq-qz6p f qaqs;y)ns, given o)- q0yq;ap)u6 fvqzqsne 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.