Which of the following macromoleculy v3emu4 m0k.yes describe a typical enzyme?

  What type of reaction is photosy +qkuur 13r)vvnthesis?

  What is the substrate for the enzym jclf:97q kyl-/51y uvlmlal1e lactase?

  Which of the following stages of cellular respiration takes place in the cyt mw(2v 4-mvp( 8qok5vn6pokpe oplasmpnk6k m8-ovqpvm( (e o2vw4p5 ?

  Which of the following would not be useful in determining the ratex sl dj0jw4qvde 1d(8) of an enzyme-catalyzed reaction?8dv4x wj( dql j01ds)e

  Which of the following processest3)78 e sy.pmdkbai1q may be described as catabolism?

  Which of the following statements p0qw-50msflt - gds * gz7kzz/eo1p4nis best depicted by the figure below?

  Which statement about encrcd3jk7v v)-:dv* um zymes is not true?

  Which of the following graphs best illustrates the relationshik:okdi7-ea ( vp between temperature and the activ7v(kadok ie- :ity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentvn;0 c+ ltnh ;yqwpl:s 681nidrations of substrate affect enzyme act 8nhcn l1n6lv:;qys w;0ipdt+ ivity.
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 outl l b6a*v6lf8 nf/vnd9vining the Calvin cycle is shown below.f8l6 fv9bv6/ nnav* dl

The image below shows the catalytic site of an enzyme. The substrate is s+smamz.*;a4d6 7h ypspl,a h ghown in black and is bound to the actzg m dp+ps,a.6 *;slam 7hyah4ive 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 metabolic pathwaysbc5 j/ w4vb0gce w33dd shown below? Letters repres/b3 04wbj5de3 cwdc vgent various products of individual reactions.

  Which of the following d;m*l.mbo pw5 d7)rfl lescribes the role of inhibitors in enzyme-catalysed reacti dprlbll; mmo7 f).w*5ons?

  Which of the following correctly describes photosynthesis or respusl dqg7 -olb* z;yjx6 u4u:wtn /q)/biration?

Many enzymatic reactions happen as pathways involving multifor z )9ysz d:q+m,1vmple steps and multiple enzy+, 9qm1mz) vo ysdzrf:mes.

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

  Which of the following best describes the i)a t (a5mqmx1y6 2i8pthno 7ldnhibitor in the image below?

  Which of the following statements are true regarding regulation by lvpmq0v.6(g aend-product inhibition?va .plg6v(0 qm
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. The dar:z seopwd0vjv8m; lk)(g ldl,ot7* zq ;;pc7kkened structure in black is the substrate and is bound at the activ jkkovps:eq,(zd 7 zl78ot *g w;0vlmd)pl ;c;e site.

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

The equipment below can be used to study the effect of temperatu-enf y6:o4k: a)lme lhre on the activity of )e6y-:fh4lom e:aknl 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 describes how enzymes isok xx.2 xl ,+ub-f(honteract with substrates to ca +olh2xx xu(bfs-k,.otalyze 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 reactions can be measu cp4bcr:k6,cnred.

  How does denaturatio .mc0i/n:n k(wymrz4ln change the properties of an enzyme?

  Enzymes play a role .*msct:r )s :j,t cuajin catalysing reactions. Which of the following statements are trjc,:rucm*s) j:ast .t ue?
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 gmq vkt ,,kzq65 w,+fgmqa;o4 ectotherms that have fluctuating body tempgfq m6qo ,+m ;5wqtv,,gka4zkeratures?

  A metabolic pathway that converts threona:byfx :l:lj/ tv(oq 6ine to the end-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it(vb jf/ xql6:yato:l: 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 o z5krj/rtqaxx4- h* f;f increasing pH on the rate of an enzymatic reaction. What is occurring during the phas;hzrfx5 /4ajt xqkr- *e labelled section X in the graph?

  An experiment tests the effect of changing sus6r0p:h )yc kdpe 4qi/6+xup7 .k wrku0i*ko gbstrate concentration on an enzymatic reaction. What could be the independent and de 7sxqk)6idphrw*oki0u/g er+y.6 kcp0k4:uppendent variables in this experiment?

  The diagram shows the pathway that converts threoyqrld;x r6nbf 8,2. zwnine to isoleucine.



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

  Enzyme A (Enz A) was immobili+nq lboo (vtl01;:vsul+3ta k zed on a matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative t v:n1vl+ blk;(l3qs +ouoa0tenzyme 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 eade 4j r03qjsp0 7kss;esily denatured. Which of the following is the best way to keep enzymes active fojs3 e00ps4eqr7 kj; dsr a longer period of time?

  Which of the followin9icc1k7 kdfn6t1 cw z o2g)a9g bhl1g/g describes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptidestbms24h1n(ti -unw5p in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzym-(sp1 5itnmb 2w4htnue 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 iwyy7iop1,k2substrate concentration. Similar concentrationsio 7piwy2 yk,1 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 no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme actipg-om+ z:+depgm+ udn p t6y5)vity, a student cut a turnip root into small cubes. They measured approximate:znpp) ge-od mt ud+ 5mp+g+y6ly 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.


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 HMG4, b-9wg c7w uffbokxva2(*:)i ciyt j- CoA reductase can lower the production of cholesvu2ic(w xf,k4b o )j *i :gayfc7bt9-wterol.


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 l v90lk.lwx; sa8c5mqare involved 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 a5lij yzczk9.f8k d,,mnd were given an experiment which demonstrated the effect of temperature on a catabolic .mlc f5y9zd zk ,kji8,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 tem;*zoikh1dj3 vflrl1nyari s/ ;,c( c4perature on the efficiency of lactase activity is tested. Which is an appropriate dependent variabl1zo cs1(ilrl;yc,nj4 / hk3a vr d*if;e for this experiment?

  A study has been conducted on the activity o 50cr+g *mqm-n k,uox(,zqgxe f a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potential*xoum(ggq+- z 0m,e nqkcx5,rly 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 xjoxvkn+u0 k5. m1uv6treating patients with malaria. Describe how anti-mxnj5k+6vu0 um1 vk xo.alarial 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 o4ckr, q zfie)o*:zn 0dpa5tq; c k4b/gf an enzyme affects the rate of react b,oitnepa:c q*4 q gk0z frc;d5)k/4zion.
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 synthesikxx4 f6gie8 yq34,fa*nkzm5 quik6i: zed through metabolic reactions. Which type,8nugq4ef 66iamk3 xx5q4:yf* izkki(s) of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzh 2kue t6j3e25-9+ ynmcix owfyme catalyzed reactions can be measurefu 6emty5k2c i32+jwonxe 9- hd.
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 re,c6triwe 57 xoactions, given one example of eac6,ct exr wi75oh 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.