Which of the followih(b;x3 gh rwx.l 4c(izng macromolecules describe a typical enzyme?

  What type of reaction7 b. +fj;fidky is photosynthesis?

  What is the substrate for the enzyme lauc4ywk :tnytz 0w 5t02ctase?

  Which of the following stages2ps s8fka;3u tvica77 of cellular respiration takes place in the cytoplasmpa7 c2 ; 7tsuisa38vfk?

  Which of the following would not be useful in determining the rate of an ep99q v*nuc8wyol .p8 znzyme-catnzuvq*p8lw.c98p 9 y oalyzed reaction?

  Which of the following processes ma(.e fw5du9 cvk8yu t4ty be described as catabolism?

  Which of the followinrb, 1 8-m d5gwnam0zang statements is best depicted by the figure below?

  Which statement about enzymes y7v xajgl r:3vak0+ akpizf:(tg+74 eis not true?

  Which of the following gr;vi3 wt;zex 9caphs best illustrates the relationship between temperature and the activity of enzymes such as lipase?;9wc;x3tve z i

1.Sketch a graph to show how increasinggifs3i)zqp z n0)x9v6gfh 1h+b3 6iov concentrations of substrate affect enzyme aczfsfi6hovinv +6px 1h3g0gi q) z3)9btivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactif5wbi 1fdj526oag bf ,9ub0m xons. A diagram outlining the Calvin cycle is show6fbwfx5dg09 1joui2 ,mfab 5bn below.

The image below shows th*s7jv8qunc n)yah9n-r3lp a ;sh kh71b2rvo+e catalytic site of an enzyme. The substrate is shown in 1s7qophj)2 ab9rul k h7vrs- n*3hnycv; + na8black 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 catalysed metabolic pmi)+h y0c;rzxd jv*4qathways shown below? L x+i)zy;c4r* 0mdqh jvetters represent various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme+l4 :u4ydz9umlzz0ko -catalysed react l9k4zol0:myz +uzu4dions?

  Which of the following correctly describes ph:6 xpkd5g)yi y 3l;dbgotosynthesis or respiration?

Many enzymatic reactions hap 6* meqfn:w5yqpen as pathways involving multiple steps and multiple e5fqwqe * n:my6nzymes.

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

  Which of the following best describes the inhi(n3n9s0yztyn;xx8- dx *fhle bitor in the image below?

  Which of the following statements are true regarding regulation by 63j q ho8wqiup85n8k tjdc+ l1end-product in3 q 5h86ow1+jnqu 8ldj pctik8hibition?
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 b6qjbe-cws//*f/zj 5 w ffk0alysozyme enzyme. The darkened structure in black is the substrate and is bound at th abcq*fwsz6j//f5 kj/bew 0f-e active site.

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

The equipment below can be use)c ji(hw m*13a eu+wbed to study the effect of temperature on the activity ij1u*h 3+ eba(we c)mwof 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 statementsw zr9:g3nvxki.*i ovs,yz r -rl+1m3 m describes how enzymes interact with substrates to catalyze reactions?1xm . -smz*3i+iw ror3kzrvn g,:lvy9
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 /7 dde,hdnkl r:23cliyme catalysed reactions can be measured.

  How does denaturation change the propeyoa;klr 0rjup7l mqhmy9: 2nnyh8(29 rties of an enzyme?

  Enzymes play a role in catalysing reactions.fnxpn9.k c)kyhy 1l): Which of the following statements are truenlyfk1 h)kx)c 9 n:y.p?
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 separate;1kv*9l5inr ,ifx4sy e-/vvjocr hp. s mammals or endotherms from ectotherms that have fluctuating body temperaturesnocil v ,i r/p.4k vj5*s19 -rxy;fevh?

  A metabolic pathway that converts threonine to thejjo ww orv9* df4d 0z4nd,(lmyx+6h8 z end-product isoleucine consists of five reactions. Threonine is convw 0jdn*do wfvx9jozlyz4 rd46,+8 h(merted to various intermediate products 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 increasing pH on the rate of an enzymatic re l;sdr1o)gxf+1x3r5 gxll*a p action. What is occurring during the phase labelled section;s r gp5l)x1rfx 31*laogdxl+ X in the graph?

  An experiment tests the effect of; ;kk.4vwdhd5 zn av.n changing substrate concentration on an enzymatic react.nhknv zkav;; ddw45.ion. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonine to isoleucy-;m 3w1pm.zz.q 2qbd xxvj 5rine.



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 comparecq(n 1ou/tlj j2;zfq f51w+ds9 ui w n)f;w/red with that of a free enzyme in solution. The graph sho suwzqq 5wl;i/u1;nr9t/f fe d1ocnwj)(f 2 j+ws 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 dp)+zbu 6upn 8uenatured. Which of the following is the best way to puz6un)+8bup keep enzymes active for a longer period of time?

  Which of the following describes some types of extt(psl9j /,d;7xt qar3z0xsuc *1vjn yracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A y /w* ben/cv3jstudy was carried out to determine the effect of increasin jvwecb /n/*3yg 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 t:x s6rhtdo65 lhe rate of reaction of an enzyme with increasing substrate concentration. Similar concentrations o ht6 do5x6lrs:f 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 activity, a student cut a turnip roo kb8xxb;me(ns: 3uy.wt 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 tube at yun;8.m bek:3x x(wbs 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 rnylthmqvfru i1f .7dn378q gl1jw,38 eductase can lower the pr j1f rnwm,fdti7y h ql gv88.3nu17q3loduction 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 dengc4 e(gtb 40 aaz;gy ;y3x r8c-ps5elkaturation?
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 w-- 29r07saqeuacm iziere given an experiment which demonstra7rsq 0-- iz uaai92cemted 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 ince+uq8n elpz//,8 po oureasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependent variable for this experu, 8p/oeznel/uq p8+ oiment?

  A study has been conducted on the activity of a specific lactase1rp 5*x gqq8cz (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce rg pxq5z8qc*1lactose-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 ne0pl+ beu4 xll50jrdx 1+7xqs(5u8ow iq po 3jqw drugs for treating patients with malaria. Describe how anti-malarial drugs are being disrsu o5i0jq (o xp qxxe+ pwl5b4ljdu 03q18l7+covered 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 a18k v4)xxnif zffects the rate of reactionf1 x)kv8zxn4i.
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 synthesizem(ckzdv6i -sf9l7d; vd through metabolic reactions. Which type(s) of metabolimv7idd6;vz9cksf l -(c reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed real: +2qnnfu2c 6dck (t1z6hi pactions can be measured. kh2qd:2a ft6nl6cuzp+1ni c(
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 reactions, giv; jxp:/zq9(yx4j gqxm en one example ofzx m g/jyjq:4p(x9q;x 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.