Which of the following macromolecules descrz,hpu 7p,fhn6ibe a typical enzyme?

  What type of reaction isq3 vxfx/y u37vx+*ll6f rnr)p photosynthesis?

  What is the substrate for the encaz(bqodmg7tgp7 z( r . 2r99szyme lactase?

  Which of the following stages of cellular respiration takes place in the cy;b2yhzt e26 wutoplasm?u;yzh6 bw 22te

  Which of the following wouldko :so 5ln8th1ynq 4l4 not be useful in determining the rate of an enzyme-catalyzed rea454kot1 nllyqnos: h8ction?

  Which of the followin8lpzqide)3v j +g-u2i g processes may be described as catabolism?

  Which of the following statements is best depicted by the figure beloro 7pxupp*vb8v*f4t* w?

  Which statement abouv 0gv 9qgo-1 iu/9eymgt enzymes is not true?

  Which of the following graphs best illusf.ew)cs bh4o.9/vefz trates the relationship between temperature and the activity of . f/b9f seozec.4hwv)enzymes such as lipase?

1.Sketch a graph to show how increasing concentrationlq8i 937 fzzkpg x33hes of substrate affect enzyme act3kpz8gf7 q3i3 l h9xezivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a690 cak +s3wug/ zwcwg series of enzyme catalysed reactions. A diagram outlining the Calvigc+/9wuc30 aww zs6 gkn cycle is shown below.

The image below shows the catalytic site of an enzyme. The substrate is sho u tahjh-rydn x-t.i0*bv.6ca9e- 2gtwn in black and i 02xia.h.-tn -9jedbt*h g-vcyt6ur as 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 descrpy t0c4hb -/dyr x7vk(iptions of the enzyme catalysed metabolic pathways shown below? Letters represent various products of indi74b(xtchv prd y/k0y -vidual reactions.

  Which of the following describes the rolh5r cgu5;q4v:d qwnq* zxps1 8e of inhibitors in enzyme-catalysed react zqw rc1uq5*ndgp q 5;4hvx:8sions?

  Which of the following correctly describes photosynthesis or 0:ve,rk hd,z)ur ; dtmrespiration?

Many enzymatic reactions happen as pathways involving multiple steps and4p axw--,l ye+ob njz/ multipl/+b4,- wnxejay op- zle enzymes.

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

  Which of the following ntnix9o 8*yo0l. nx1z best describes the inhibitor in the image below?

  Which of the following statements ar+t zapca) 8f/we true regarding regulation by end-product inhibi+ aza p/)8wfcttion?
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.k/5f dduow2 3b The darkened structure in black is the substrate and is bound at the ac2dodk/wbf u35 tive site.

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

The equipment below can be used to studyarmxa,q:kbk-,a- 3 c rig v9ls)5 z4iu the effect of temperature on the activity of the enzyme amylase:ausac,4,rma q3l5ik) k xbri- 9zvg-.



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 inteafm2p+/k 9 3zo5lopsi ract with substrates to catalyze reacti2k 5 a9fomiz ls/3pp+oons?
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 reax:m--t;omha6w r6jx emr.lv7ctions can be measured.

  How does denaturation change the procbb +y)nx7r(2fi)e: pgf;6kfwmkqemit 0)h3 perties of an enzyme?

  Enzymes play a role in catalysing rea 03ktpziecp5lq1 3w q+ctions. Which of the following statements are wltzqe q0kcp+1 5 33iptrue?
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 endothe;,(; itqne+ ujq bznmmq(2+ncrms from ectotherms that have fluctuating body temp+qqztn,2(j ;;qnmbum( +c ineeratures?

  A metabolic pathway that converts threonine to the end-product is4 6 qtnhnqn)nlw4x 1b(heg;+ voleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different hn; 4g16b4) nx hewnvqt+qln( 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 eff6n( an4-ohq* slfy, ufect of increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in tayqnhs6lfuno4(,f - * he graph?

  An experiment tests the effect of changing substrate concentrpqb6 n 7uep.(;ny d:bration on an enzymatic reaction. What could be the indepenud;:6p (qyr.be7 npbndent and dependent variables in this experiment?

  The diagram shows the a bkzvsp2xnbo;9bb 4v.re:; 05tsr 7tpathway that converts 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 it;s.pai mgdk+)h*l 5dgr( fp4bs activity was compared with that of a free enzyme ings ma)bhpgk.f*(ip+;dl4rd 5 solution. 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 u6qllupq n u4j95f( tl347 vqvf 3fyc4easily denatured. Which of the following is the best way to keep enzymes active for a longer period of tim 4u4l9jlvfu4tqqp7l nqyf f536cu3(ve?

  Which of the following describes some types of extracellular enzymesn1k r6j z3.hrdg0fd b 79hrop6?

  The enzyme pepsin hydrolyses prg(xgj* dr*q-toteins to release peptides in the stomach. A study tdgg*(j*r xq- was carried out to determine the effect of increasing substrate concentration 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 substrrt1 e/n4jm ;ojate 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 t; oemr4 1j/njno inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a turnip r- msvwbiep/rxl;s:8;;te t0eoot 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 wa sx:rle;/i8b ;;pwe-0m ttves s 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 below. Inhibitors to the enzyme HMG- Cosl0mytz8v (d0A reductase can lower the produsmz tv80 d(yl0ction 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 involved in denaturation?yp2fr/u jknri)z, 1-v /2abjy
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 react5i+wmrs8 ) )zzen hvljk44r1dions in the classroom and were given an experiment r zhej5 mksivrz8)44 )+dwl1nwhich 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, thete1*cpwhx k2yoa,9n;/ n3 bo 1h;drf fd) 7jhd effect of increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dep2dy,7)th; 3j1dbfra fwn h1np9/ehdocox *;k endent variable for this experiment?

  A study has been conducted on the activityi y7h 7yugilv k83up67ixnr(- of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used asv pgrii67hiuk -787 yyl(unx3 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 f8oc8 3p5 zwmglz cji,o;cth +*or treating patients with malaria. Describe how anti-mala5j zc+gomwc;c8pt i3ho l,z8*rial 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 r/b7 ouz*gy h5enzyme affects the rate of reac5ry g*zh/7 obution.
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 synv4m;zessxgdbu 95 w+8thesized through metabolic reactions. Which type(s) of meta5s 8; 9+vwubxezgs4mdbolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the differe*bryig p0/8 r,tule2qr /f5h vnt ways the rate of enzyme catalyzed reactions can be measu50pyq hg ibu,retl /*rr/fv28red.
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 extracell o7c0i)tkaz g;u2ki(m6 jb/yg ular chemical reactions, given one example of each typei)t/z0jigubk6oka(g m;2 c7y 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.