Which of the following macromolecules d5wwmb65k9eo b escribe a typical enzyme?

  What type of reaction is photosynthesip mp 6*dq+ 2u37ccwdlzs?

  What is the substrate for q7af igq i/p,nm2-f cooz 93c*the enzyme lactase?

  Which of the following stagebyw(t5m:vz8o gz a- g6s of cellular respiration takes place in the cytoplasm? z gz :-(5t68gyamvw bo

  Which of the following would not be useful/ zsd;yt 0-tze in determining the rate of an enzyme-catalyzed re;td y t-s0ze/zaction?

  Which of the following processes may be described as ca7v 7g zyxhduc p9o 0(d,ap5c)m.kowebi6e9 1ltabolism?

  Which of the following statements is be me sz 1q6atjs7wsuix/vo- ucdwy6+ rq3* -0,yst depicted by the figure below?

  Which statement about enzymes isj*r .v,ij 8xylrfk( .z not true?

  Which of the following graphxf,(imoosl,gvy rr ,v-j6q*; , i18e 7qywezls best illustrates the relationship between temperature and the activity of enzymes such as lipasyol qyx,6smlz v1w-q;e ,r 8*fi,j e7, orgvi(e?

1.Sketch a graph to show how increasing concentrations o+3d4,*bmq9c i20pyjhqhxhcm4 :cf hz f substrate affect enzym,cyp4+9qx4*j2zchhdiqc:m 3hmf bh0 e activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a s7 7 1wn91fw wlm+vzwsieries of enzyme catalysed reactions. A diagram outlining the Calvin cycle is shown beloi9nfwmw7+ swv7 zw1l 1w.

The image below shows the catalytic site of an enzyme. The substrate is sho s;iragi24x fxf ,y0kh f3031uac ahm.wn in black and is bound to the active gf.0xrhffacixu,aa; 033 412mihky s 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 tzz q tx,t;lwxq ost ;8;4i1i/ihe enzyme catalysed metabolic pathways shown below? Letters represent various products of in8zit1;qtqt ;ozxs li,x iw 4;/dividual reactions.

  Which of the following describes the rolqgf 4bzejg*4vr 509 pqe of inhibitors in enzyme-catalysed reactig4 v5z9jb*4f eqq0g prons?

  Which of the following correctly descj tyi hqod,le8uu 9s:y 0po;/;t8u3ffribes photosynthesis or respiration?

Many enzymatic reactions happenxk - pwjo;3-35klkmzpu pn6r 8 as pathways involving multiple steps and multiple enzymes. p x36-;5l pkkopkz3j - numw8r

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

  Which of the following best describes the inhib;qu1: k 6gmuxiw*8bb citor in the image below?

  Which of the following statements are true regarding regulation by end-ar/6o,z4 8qt- u ;qaq.fc mt8ir3ges wproduct inhib-8qr e;octf iqzw,q8ugt/ 64a 3a.smrition?
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 lysozy lxs3i/oz.l wh;tf-u 4me enzyme. The darkened structure in black is the sub ;ftwlo/zxs.ul43 i-hstrate and is bound at the active site.

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

The equipment below can be used t3us ,)jjnwmo , m2wpw)o study the effect of temperature on the activity of the enzyme amylase.o s 23wnjp),j ,mwm)uw



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 ic,3raz ;t/z v0fqyru3nteract with substrates to catalyze re z z3; tqarr3f,0v/cuyactions?
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 catrucq8 d6b /7/qvpj 7pqyi4k/u alysed reactions can be measured.

  How does denaturation changel u+eh; *h-rpf the properties of an enzyme?

  Enzymes play a role in catalysing t0df2.qqvab. 24v w bqreactions. Which of the following statements ar t2.a fqqqwvvd02bb4. e true?
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 characteriio- tn orh5u+pw) k2os e-:q*b pyk;p6stic that separates mammals or endotherms from ectotherms that have fluctuating body temperatures-;ryuto+5 - op:6e2b i*on p)skkqpw h?

  A metabolic pathway that converts threonine to the end-product isoleucinninvhx3nk +47n pxy k1*5c 3fhe consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it f1h5 vh*nk43nipcny3k7+ xxnis 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 increjstaf0ie8-r8+ qva7 gasing pH on the rate of an enzymatic reaction. What is occurring during the 0fas gti87-q+evr j a8phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration 4 cbuf)g)) unjon an enzymatic reaction. What could be the independent and dependent variables in this experimf ujn)b)u)4 gcent?

  The diagram shows the fn p9d1ak+rm8 pathway 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 its activk:-rbmgo ,ie )2n 2tgmity was compared with that of a free enzyme in solution. The graph shows t2kb nggr om:i2-),etmhe 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 is the best way togo p4,liskc7 7 keep enzyk c7iogp4ls7,mes active for a longer period of time?

  Which of the following describes some types of extracellular en gq6u+5 ndsff)zymes?

  The enzyme pepsin hydrolyses proteins to release peptides in t+ hp- t6mjkt.x0:bhqnhe stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperatu m6-bp+tjh q0xh: tn.kre 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 r y 0lpxp2)qht n)cgv43ate of reaction of an enzyme with increasing 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 theyv0qt )2)4chpxg lpn3 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 a turnip root n),rm(4w -o -hff lalw /wzzi4into small cubes. They measured approximately 5 g in a weighing dish, addedza( ,4r-mwllwonh)i-zf 4/ wf 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. Inhigv4cs8,9bojr l : wt.vbitors to the enzyme HMG- CoA reductase can lower the tw vs :ol 8jv9.b4r,cgproduction 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 involxm r 3-bnm-fd, 5yc2elj8d5hlved 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*mn2v l7x 9je0yma jsj6um +v3 in the classroom and were given an experiment which demonstrated *7x2vj6m 93 um0+ jmla ejsnvythe 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 0z 2r5dt qr92uezcz9xof increasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent va0tq29 dz95rxrzz2cu e riable for this experiment?

  A study has been conducted on the a9c4m zo9sn +oyctivity of a specific lactase (Bg10), analysing the effecz9+9 4ocs mnoyt of pH, temperature 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 fn8h+du0ko phm+ qw:k- ind new drugs for treating patients with malaria. Describe how anti-malarial drug8wd+hn :pqou -h0m+kks 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 ;9h4/s auqoddof reaction./d9o us4aqdh ;
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 thmi;xzi1nf*r)d ,m c;g rough metabolic reactions. Which type(s) of metabolic reactionsfimr)m*1c;nzd g x;i, are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactio0jrnoq 41ia9 l ydb0b-k8d wp0ns can be measu4n00dpk-8aji0 1r yb9 dbwloqred.
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 extrac.+ fj9, bynzt6d m+3a bm-zvawellular chemical reactions, given one vmmf9z d az+b3abn-,6w.j+ ytexample 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.