Which of the following macromolecules describe a typical enzym .sglq+wh5*lh m7kdg1e?

  What type of reaction is ph1a vq7 yocy+:gotosynthesis?

  What is the substrate for the enzymee/2n85sl hwvpon5r q4z yn8 s4ko;gg . lactase?

  Which of the following stages of:rx+i; vbgdk+ cellular respiration takes place in the cytoplasb iv:+gxd ;kr+m?

  Which of the following would not be usdh /.h:*6hmh* xgxfqhd8: fgt xq05t heful in determining the rate of an enzyme-catalyzed reactionhh:*dxthqfd 6q g.g5h fh0x:ht mx*/8?

  Which of the following processes may be described as k+rp w)l(lm :xcatabolism?

  Which of the following statements is bes6z99(cg a:ezt .zoqykt depicted by the figure below?

  Which statement about enzymes is not tru1u( o.zpsk 2ls;y(kbce?

  Which of the following grt(o0+(mpxo4tzco.i ecyd57 uaphs best illustrates the relationship between temperature and the activity of enzymes such as (o dzi c oy7.c(etum+4opx 0t5lipase?

1.Sketch a graph to show how increasing concentrations of substrate affect; -uqwkmmve5t7 )7r-vremb ;i enzyme activi tw7;-7 mv-m5m b rrqkvui)e;ety.
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 )z u/ i(b6woutbai+0adiagram outlining the Cal+ibu6 /ub)otwz ( 0aiavin cycle is shown below.

The image below shows the catalytic site of an enzyme.i ngt0ifcmh ug//)1j1o aip. 7 The substrate is shown in black and ioti uj ifp/ c 01i7).gahn/1mgs 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 pathways sh iidt: z4c;g3hown below? Letteriz4 gth3d:;ci s represent various products of individual reactions.

  Which of the following 4 dc0lj /co.l9w j4kyy m;kmn6describes the role of inhibitors in enzyme-catalysed reacdc/mknjwjy k4l;.l06y4mc o9tions?

  Which of the following correctly describes photosynthesis or respirar brku4nab48k ltu.*0fmb2w 5tion?

Many enzymatic reactions happen as pathways involving multiple steps and 7o;m .+xn4 m7wo elqy3 o1ycirmultiple enzymic4 y 7 ooxwq+reo1n3y7;m ml.es.

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

  Which of the following best describes the inhibitor in the imagu-e8xcl )6woae below?

  Which of the followi:gygr o(*aj2qm9j b7q;: j mfeng statements are true regarding regulation by end-product inhibition? jj2:jq9frm *myaqg7;ebo :g(
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 bdu/9 x s)ktatud6+ *9tvzcf* shows the structure of the lysozyme enzyme. The darkened structure in black is the substrate and is bound at the active site. *t 69zuct uktf*+svxd bd)9a/

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

The equipment below can be used to study the effect of tempyhg0t ,u*xl ;nerature on the activity of the enzyme ngh,l;uy0t* xamylase.



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 with substr-z 38frxa(w77tgxprl wd3 ,cqates to catalyze r8grq cldrpf,3 (zxwxw-3 77at eactions?
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 :ks h87*z/geppt.t pb can be measured.

  How does denaturation change the properties of t. xeah/;e cit+3t3 lban enzyme?

  Enzymes play a role in catalysing reactions. Which of the followipf6lt 2y by,n,( ndq4nf2m4inng statements are tl qnifbmy n dtf64(4yn22n p,,rue?
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 tzm -3l .hi4m,bhjp.llhat separates mammals or endotherms from ectotherms that have fluctuating body tempehj.l4- zh mi,.ml blp3ratures?

  A metabolic pathway that converts threonine to the end06xsr pp n0e5h-product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme in the p 6pnx5 0ehsrp0athway.
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 incagc)i nd0 j,6mreasing pH on the rate of an enzymatic reaction. What is occurring during the phase labj in6a,g)md 0celled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzyma,hb6 .+krkm kctic reaction. What could be the independent and dependent variables in thk rk+bc,mh.k6is experiment?

  The diagram shows the pas ze +8ws(g8 *7gxbwyfthway 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 b nv3+t4 kwtz3dd cc*4its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-axictnbk4 ddcwtz34 v3 +*s).



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. Wtjqdoxywp7 t*)m j hb)n7/n49 hich of the following is the best way to keep enzymes active forj dj)t9wy4mnothpn) *b7q7 / x a longer period of time?

  Which of the following describes some types of extracellular en+wr7 7 fxom gqbl g2;ci 8u28mylre*9i+dt 1hszymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomachtux0cfg/v9n )0(4a .nix hc0ltmvq3b. A study was carried out to determine the effect of increasing substrate conb 94nc0l qtun(/x00 c)3xv.ithfam vgcentration 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 increasio acxc6nyv)w 5r1z2-yng substrate concentration. Similar concentrations of chemicals A, B, C and D were o52ra vnywzyc-6 )1cxadded 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 alxu7hndyo4+;, h 3s(ofpio0s 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 was stored in ao ;s(4fu o +ipxsd,3lh0hyo7n 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. Inhibitorsrx1, y3 (fk baoo9;ocd to the enzyme HMG- CoA reductase can lower the producxdoy1 ,o ;bcfa(3o9rk tion 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 sse6 kncf .3u 6en:zm.zu/p(*7n dprx 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 a 4d-sdf o)dy-hnd were given an experiment which demonstrate-)dd4s- hfody d 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 j,7su4 5sy,rmb4 utu md ,/ hmjpab7v5the efficiency of lactase activity is tested. Which dsusma5y7b,h,r m4 7tvu 5j,jmu p 4/bis an appropriate dependent variable for this experiment?

  A study has been conducted on the activity j0c1kmb 2tf s1:zuxn0of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentiallyb0z0 xu jf2 sn11ktc:m 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 ttouwdbv-r0w:vux 05( l .e5vuvf ,3z po find new drugs for treating patients with malaria. Describe how anti-malarial drugs are being discovered with new technov3w5rdvp0 zoutu5x-(fe .wb0: u,vlvlogies.
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 thdg0ynk +8;u hue concentration of an enzyme affects the rate of reaction. gd8unu;+0yh k
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 through metabolic a.rkqf mnmm-yl l7hfm3 /un)7p )y4z 4reactions. Which type(s) 4qkn)l4)m3h-z l. yrpa/7mmf u7yfmnof metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways ther9wgl7y8 .rqa rate of enzyme catalyzed reactions can be measure87 wr9gylaqr .d.
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 cva 4bmp1go)4bo;bt(m hemical reactions, given one example o4tgo)mb( a; mp1v4bb 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.