Which of the following macromoleop s2z:t;8c up4r isf q7,em8ncules describe a typical enzyme?

  What type of reaction is photos 8y-p nlrqn66jynthesis?

  What is the substrate for the enzyme la4+a s m7y8v5a jxcuu4cz(;fcn ctase?

  Which of the following stages of cellular respiration ta- (g9jrz.g- d fpl(ah4uex2v ckes place in the cytoplasm? 9(-(p-4zh. jxlfar2evdg c ug

  Which of the following would not be useful in determining the rate of an enzymenivyu5; cy2qi7s44 nk-catalyzed reactioniu5ni74cqs4 ky v2y ;n?

  Which of the following processes may be described as cy0zm1 *eqk :gkatabolism?

  Which of the following statements is best depic-ko*5opw1ojv /ytj0( ce/k mhted by the figure below?

  Which statement about enzymes is not trnc0p0u3 yumd1 ny1 wf*ue?

  Which of the following graphs best illustrates th1.sczfqw 2fil v8m +0ee relationship between temperature and the activity of enzymes such as lipl0iw+s2qf e.z f1mv 8case?

1.Sketch a graph to show how increasing concentrations of substrate affect a ez e2ha ,j8dapg-4q4enzyme actiz agah-8epqj24a,4 devity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a serisn 0ju 6 :casb(w-)wuaes of enzyme catalysed reactions. A diagram outlining the Calvin cyc w bsnc6 0as:jw)-uu(ale is shown below.

The image below shows the catalyt4-( fu9nf ceymic site of an enzyme. The substrate is shown in blaf uc( 94-mfneyck 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 the enzyme y s.k5wn:lp/vcatalysed metabolic pathways shown below? Letters repres:pk.l5swvy/ nent various products of individual reactions.

  Which of the following describes the role of inhibitors akc.b 2h hphzs(4p9 sc7 )z( tjkp7c2oin enzyme-catalysed reactionp (bc k 4p (hja2szso.h czph9ct77)k2s?

  Which of the following correctlm*gllb ozjv87 mw,-/vr - ym0dy describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple ster 1k65axzs bc*ps and multiplz*cbs1a65 xkr e 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 image beloi: b92s 0,tdnlj+vynoix j2 e,w?

  Which of the followiy g6zlrze(wp ok 2w238ng statements are true regarding regulation by end-product inh2ol zp3g(r6k ww2ze8yibition?
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 lysozyme5zs38icct kxho6 0pa, enzyme. The darkened structure in black is the substrate and is bound at the active site.x0ktp3sci6a,c 5 oz8 h

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

The equipment below can be used to study the effect of temperature on tgkn6 t ji67b-6/i p uckc/n)aphe activity of n6)66cc/ib kit guk7pj -/pan 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 d.qly)u /p+pwo8m* zxt *fcos2 escribes how enzymes interact with substrates to catalyze reaction+csp/t xm8op*q)2lu fyw .* zos?
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 cpub bmt,2 g0kn 59ql6katalysed reactions can be measured.

  How does denaturatiosc uxnx/a ez8z4,:n)i n change the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following stato1q222:n jqvn 5zer rcjjki;2 q0 46o vevwc9hements are true?vcnhnv22 ercr 2 :0vk; j 41wqqj6z2j5 eo9iqo
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 endotherm 89zzp5b( dd ni4+p :vp-ojok5ytkq9 vs from ectotherms that have fluctuating body temperatuy99ozdk ob d 54v n-k(zj+pipv:q5p8t res?

  A metabolic pathway that converts threonine to the en0li 6ph k,+xpnd-product isoleucine consists of five reactions. Threonine is converted to various intermediate products seqh 0x+nkip,l p6uentially 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 ratwmye6f04 kb 4qe of an enzymatic reaction. What is occurring 4f40 ybqe6kwmduring the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentrat.jhtw au()(bfion on an enzymatic reaction. What could be the independent and dependent variables in thist(wf . )(bhjua experiment?

  The diagram shows the pathway that conve3 w9mc(:xmwbg rts 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 its activity was compared wit swjuk nbd2zz4(h7 2w8h that of a free enzyme in solution. The graph shows the relative enzym8ww2hb(udk4 z j7zn2se 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 denaturedmn4sub)2i p48rg* pgdij ,st5. Which of the following is the best way to keep enzymes active fo sp44jp*,5i 2ts)in mdgrg u8br a longer period of time?

  Which of the following describes some types of extracellular enzymes?6fsr;vy9:1ps so*amfpn t9qx)6 4ckm

  The enzyme pepsin hydrolyses proteins tosyfuo0 ij, ii/ (:e1bh release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentr1oi/hfu:y eb j0(,s iiation 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 increasing submruko 7e5xiwklzb5 /ay/+m 2)strate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activx i/beka 5/ry o+m72zk5w)ul mity 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 kzu89g+k p+ gca 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 tzgpg8u9+kk c +ube 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- CoA reducta/xok7t fho;-ese can lower the production of cx -; tf/e7koohholesterol.


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 involved in denaturatiowb gjmdby57 n /40ff(h*4g dvuen)l.cn?
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 in8r,8ox d3i(je * q9(tsmecbkkzb8(m b the classroom and were given an experiment which demonstrated the effect of temperatured9s 8rbe*3mxk oz8bbmjq,8( (i(te c k 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 i+s;hu xkv 6rj+wym* e:ncreasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for thism+kv wy ;rx*ju :6e+sh experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), analysbdlz zp)22b8olcl) / ling the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produc2 l bop2dzll)z bl)/8ce 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 wi0qe3nt tt3q tx /s.2rvl,;ytq th malaria. Describe how anti-eq3tr tsq;qlt,tv3x. ty n/02malarial 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 c,d:;uw mhj., xenyam+: ovx8ioncentration of an enzyme affects the rate of reaction. xui. ,8x,vma+nyd:e h w: m;oj
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 reactioncs3j 4 a*wne1es. Which type(s) of metabolic wesae 14nc3*jreactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways th 3etq75v;ukcd -wzax j9i0phy:g 09gte rate of enzyme catalyzed reactions can be measured cdegw0h3a9z 9;i 5q7x-v:ytt 0pjguk.
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 extra7qdoyew07fj4(nl h6 sbxj0 7dcellular chemical reactions, givenyj4ldshb06qn0w7f o 77 (edjx one 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.