Which of the following macromolecules describe a tbd*+ z rjk;aj4,rtgzoiwo c6n..(; qtypical enzyme?

  What type of reaction is p:l +g ,t*uvs:fy(ouy photosynthesis?

  What is the substrate for the enzyme laci 5(bvgkmfi:2( d ilx2tase?

  Which of the following stages of cellular respiration ta)iwit6t2: z +xj9 uxxxkes place in the cytoplasm?w 2t)z uj 96ixixxt+:x

  Which of the following would not be useful in determining the rate of an enzy+h f ott9* t9cg:l,cbdwu*0sj0co+tf me-catalyzew9f9bg0jc +tts *dhl0t,uf:c*t+coo d reaction?

  Which of the following processes may be23btvaggu3do , x2s3w described as catabolism?

  Which of the following statements is qjo2vrynsvf8:zu:88 best depicted by the figure below?

  Which statement about enzymes is not true?;4:6jr ghxb ycc5zd- u

  Which of the following g zwd z)l*nzqxv:/- j6graphs best illustrates the relationship between temperature and th)6z:x- *wdzgzjln /vq e activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentration5uu6 vet:+ ysns of substrate affect enzyme activity.y6+sn vu5ue :t
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 outlia*l 9 f2dyr5zening the*def5y a2z9r l Calvin cycle is shown below.

The image below shows the catalytu7 -m,5iugzgfwyqpxg ; q5h9: -mha z)ic site of an enzyme. The substrate is shown in black and is bou5zg;x m h9ayhfq-uiqzp:7 5g)umg, -w nd 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) tvn0, tni1frisuzf1;6 7kkk shown below? Letters represent various products of individual reaction,1s f nv0zi6ui7rn 1 k)kk;ftts.

  Which of the following describes the role of inhibitors in enzyme-catalysw6x dc f38cz2aed reactc df3 w2x68zcaions?

  Which of the following c98i snea3)d coorrectly describes photosynthesis or respiration?

Many enzymatic reactions happen as patp,9 c3u(pnwyfv45 zu-oq py5whways involving multiple steps and multiple enzyme4p9wu5yp -noz cuf 5y3w(qpv ,s.

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

  Which of the following best describes the inhibitor in the image below? v rap+/hn, cd* (.s1x lcn(oro

  Which of the following statements are true regarding k 0,zkyl6gmz 24dmes*kq*u; mregulation by end-product inhibitq kmkl6 ,zmdse**42 ; 0yzkgumion?
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 enzy uvdj0jv-fowknxc8.c;v0lj 9w)4eb*me. The darkened structure in black is the substrate ecc80) * j4f9ujk-djvwboxvn v;.0 lwand is bound at the active site.

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

The equipment below can be used to study the effect of temperature on the ainry3lh s81e.o n; b+l :igg(activity of the enzs a l.hgyr:3 iiebgl(o1n; n8+yme 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 how6b- 0bni32t4ratab k ,xq5iox enzymes interact with substrates to catalyze re54r0tk- 63 ,n btbqix ix2boaaactions?
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 enzydb8y :tg08ewcme catalysed reactions can be measured.

  How does denaturation change the properties of an enzyme?op2 yrwl /9,nxzu7 j83 j2aihu

  Enzymes play a role in catalysing reactions. Which of the following statemenkdch /gk ;0s+lp9 bm;xts are dm k+; /lhp;sxkc0gb9true?
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 gcnd98 ; r,rnuh:eft*separates mammals or endotherms from ectotherms that have h;,ndr etcrf*8un : 9gfluctuating body temperatures?

  A metabolic pathway that converts thwid*4v4z85z;n wvw ti reonine to the end-product isoleucine consists of five reactiowzw4w58* vnti;z4ivdns. Threonine is converted 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 dab(uwz;al. 5 the rate of an enzymatic reaction. What is occurring during the phase labelled sec5; (w.azlua bdtion X in the graph?

  An experiment tests the effect of chaysnh35bzkp4;p hh o(9nging substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this exho3;k4ph( 5nbzs9ph yperiment?

  The diagram shows the pathway that converts threc8g+w+0y eue c/r4ntlonine 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 activity was cu633ed(g 3 iermfw /lq;n0 1eq ukl0po8m)fv bompared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with vup13vrufgbliw 603(8q30em elq / me );n fdkoarying 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 foll .mss/x36uwsi y:bz2 dowing is the best way to:xsb w6s. d2umz /yi3s keep enzymes active for a longer period of time?

  Which of the following describes some types of extracellular k4yquz7) hsm 7enzymes?

  The enzyme pepsin hydrolyses proteins to releaa(-ur l6 sx,3vx 8+q age4sberse peptides in the stomach. A study was carried out to determine the effect of increasing sus6-gl4e qevrx a +a,ur3(8 bxsbstrate 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 subd yxzl.17gb7jgso d:re/,ky, strate 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 coincid /s oeyz1:.dg7gb,d,rjky7lx es 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 stuqu /5gvd:o 6+e8jsq8q gt qkp1dent cut a 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 tqpg t6v+o8q 1k juqe85:/g dqshe 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- CoAl+f c e:*ey5fj+dx;ij reductase can lj:cy+ e*d+jl ;ife5fxower the production 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 involved7i;d2/bj+fm+ 7wbt2ndj ukxg* o d po; 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 react4iv9,dk/x 6da/- kojpngkip,j2eml8ions in the classroom and were given an experiment which demonstr,2 8pp4dgoj k6-ivan9el,k dix/ mk/jated 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 ofi8 5uuv/c:buz f :f72e9os zik increasing temperature on the efficiency of lactase activitfuzvz 8i k: fub9su27 c/5oe:iy is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactase (Bg10), anak/anf6nm yc: j0fbf;yxi0dv g 1/h;(alysing the effect of pH, temperature and glucose concentration, as it may potkdch y:b 0 f ;j1a0/fin(gy a6v;fmx/nentially 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 treating cip/3hx cu; u;patients with malaria. Describe how anti-malarial drugs are being discovered with ci ;pux3u;h/c 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 cor0y) j h9x shg:uw 4wu+jp6og-:lql /n2p3f fvncentration of an enzyme affects the rate of reaction. sjlwqphfjlryp-uxv g +o/ fw 6un39 hg) :02:4
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 synx-.(iys.m g5 pnf 8isvthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation . m5iinsgsp vx (8-yf.reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reav)d0 wpu udf4: mpx7t2ctions can be measuu2d pv:m40tx dup )w7fred.
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 extracellularbf(-(nunnoq ds-/uj lm; :u s2 chemical reactions, given oqfum(noulsnd2- sj u;/:- (bn ne example 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.