Which of the following macromolecules describe a ;n.3l cih5skitypical enzyme?

  What type of reaction is photosynthes3l,1doscgt 4 6b- zc(yetg ;nhis?

  What is the substrate0/m/3lyczxypb4.etxr ,v yh 5ph ,s:i for the enzyme lactase?

  Which of the following stages of cellular respiraty -j7o8 dqt,au gxl*c-ion takes place in the cytoplasmty7l ju*-8go c,xq-da?

  Which of the following would not be usefuy: vxk gh1u-y 2n2xi)fl in determining the rate of an enzyme-c: x1yvgi -h y)x2uf2knatalyzed reaction?

  Which of the following 6rab;f ucl6d- processes may be described as catabolism?

  Which of the followin qoxpqc tf53;wree,:+g statements is best depicted by the figure below?

  Which statement about enzymes is no5etce y(+bh nl5 f)3jft true?

  Which of the following graphs best illustrates the relationship between t2 (svvbv h:ka/ydl;c7 t( rg,nemperature and the actrvatbn:7c(vl vhg/, y2;ksd(ivity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substraq k79gp+ v,znfu8lf,t te affect enzyme activitzuqvl k78,ngf9p f,+ ty.
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 d)v-p md93xonjiagram outlining th9vxdm)o -3j npe Calvin cycle is shown below.

The image below shows the catalytic site of an enzyme. The subby 5 meggs7ogl-r ns*m9;).mdstrate is shown in black and is boungem-7;.ymd )sl go 9bg sn5*rmd 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 e,fa0whz(cx 4qnzyme catalysed metabolic pathways shown below? Letters represent various products of individual react qwzax40f h(c,ions.

  Which of the followinn xpy2kvzy.iaui q i)c*8 r:71wgk0g +g describes the role of inhibitors in enzyme-catalysed reactionp)c.ivy*y 1n qwk 2gkz7irg+0ux:8 a is?

  Which of the following corre twj (1n:5hvz mlhlq s3i)7xh+ctly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways invol;hemdg.s 4 1wwving multiple steps and multiple enzymsew.1wd;h 4g mes.

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 belowle xmblr;h+p6ooo9 *l29w uqtrqa 668 ?

  Which of the following statements are true regarding regulation by end-productv0mpd:u v m9jh4ixs9. inhibitiom9xd s.vm4u9: p 0hijvn?
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 struc)l8gld dxpo)u4w,i:, -kah ndture of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at th-g, oxd4)kild 8 a, )lwudnph:e active site.

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

The equipment below can b+p9 w.tk+n/evepz2nu .7ibm n e used to study the effect of temperature on the activity of the enukn.m zi+ pebw+n7pnvte.29 /zyme 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;k dd/oiqe 8 q)qj2s+s ruw.o0 with substrates to cajdqw)u0q;2 eqris 8 .ds o/+oktalyze 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 enz-80) qcocdmk oyme catalysed reactions can be measured.

  How does denaturation chadc8 8nnv)t+x) t8 2ki-omdmjn nge the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the followinl-5f1)uewg0fy a, z vog statements are true? gwz5al-, fyo1 e0 )uvf
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 separat8n 5lk97 )j nf8r* hfbqkebli4es mammals or endotherms from ectotherms that have fluctuating bek*bfij5fk9ln8 nr 8 bq lh7)4ody temperatures?

  A metabolic pathway that convesv;e: d tp(ei/k 33 c;mhfaf3:oxd9a zrts threonine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate prpfm/3zikfosct ax 3:v ;9(dh3 : aee;doducts 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 increas9dc3 yie29r6uh:h w qping pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X 2h9 i3qu6 pryw:hd9ecin the graph?

  An experiment tests the effect of changingsml 2lz4r56k d-b/f us substrate concentration on an enzymatic reaction. What ss 5z6 r4lm-lud/f 2bkcould be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to i4:w3hmoktsd l w05qe* soleucine.



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 compare ogsvw7e1 )omx-;8oozd with that of a free enzyme in solution. The graph shows ox8gwo1)m oozv7s- e; 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 i 5c mjn(fk2hpm0v :4,cp ibr)tl1cm:bs the best way to keep enzymes active for a longer period of t4k1,t m: m :bf0m(j 2c)hvbcpn 5rpcliime?

  Which of the following describes some types of extracellular enzyfyspv ea.; 5;pmes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stoman5g2gmd7hy o .j(cpe)ch. A study was carried out to determine the effect of increasing substrate concentrati5 2 op.dc7gjg h(m)eynon 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 increakg npsf3r.+j ji- :a)i .x.aijsing 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 inja.kpr sxg+ fi )3.a j.j-:ithe enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a sttd4e 6zw;7a qcv1 yip(udent 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 wp(t; 71i cdaqyw46zveas 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 enzymer4xs(nc 3o a16ja pq.5*-ukh0w*mgck:huz lp HMG- CoA reductase can lower the production of cholester -:ua5um 1jr (0pqcnh6x hklas *o*zp.kc34g wol.


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 slx- 30v q q-kzoau7n: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 werws 46 9uwd/byb 7mj+qjpb4rc-e given an expeb4 bq c7wrpu9b6 / jyjm4-s+dwriment 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 effect of increasing temperature on the efficiency of laz.5 e6obt2;q,daptafyz * nf- ctase activity is tested. Which is a oe6q2 p.y bd5z;ft fz,-n*taan appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), phr*o 4ns5j58, kji qtanalysing the effect of pH, temperature and glucose concen*r iqo 58j ,5nhjspkt4tration, 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 fv51-+ymc +cew8da.(bilj rkdind new drugs for treating patients with malaria. Describe how anti-mdaw+c5c 1+lvkym8 e.rib- d (jalarial 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 qrel v6;7 / l,6b mewanjhvg(*enzyme affects the rate of reaction/v( awb j7vlle 6hqegr6;m,*n .
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 dohxu:fbrd me b6pps,7n6q3 90nwn or synthesized through metabolic reactions. Which type(s) of metabolic reactions ar fe7nb0pqmr6s6x3n d:u b9h,pe condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions can be4)amh5kce3i /3fwezy measured. i m3 4/ kzeyha)3fcw5e
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 extracelluyu 3hz2dhv8 1id7d(bhlar chemical reactions, given one example of eac3hhzd v8hu21d(i bdy7h 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.