Which of the following macromolech1. 4,n2l pm +xw cc*rkdkbhh3ules describe a typical enzyme?

  What type of reaction is0yd *sh/da*vrcp7 9r f photosynthesis?

  What is the substrate for the enz9/w4jtlwyc 2lz+ d,ub yme lactase?

  Which of the following stages of cellular respiration-yq+nlgs 6 p0t takes place in the cytoplasm? tpy-s6n+ q0lg

  Which of the following would not be useful in determining.phcw2h 6*(i xxmui t: the rate of an enzyme-catalyzed reactioui:ch x*(m .hx2p6i twn?

  Which of the following processes may be described as catabo 1jprqxm6qp:+lism?

  Which of the following st dv),)+sit m1(bwsrzp atements is best depicted by the figure below?

  Which statement about enzymes il) jmj)ogkduc-;.w j9s not true?

  Which of the following graphs best illust ur+53,(bg8wfl ka ffxrates the relationship between temperature and the activity of enzymeskgf+ r5ub,(fxal f 83w such as lipase?

1.Sketch a graph to show how increasing concentrationssoec0 nwkl s/6u802pk of substrate affect enzyme actip2uks80 w6s c no/k0elvity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series6s ao5co3ffhg j.4u f9 of enzyme catalysed reactions. A diagram outlining the Calvin cycle is s f c5oj 4au3f.9gs6ofhhown below.

The image below shows the catalytic site ofnkr qpil(:)y3 an enzyme. The substrate is shown in)pk rni3l: (qy black 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 pathwaib ec+p01tvpv mp2; -jys shown below? Letters represev2+ -jvm1pb ;ppcet0i nt various products of individual reactions.

  Which of the following describes the role 9b+9v+,4 kjdv/5tspr kx klh aof inhibitors in enzyme-catalysed reactio+/tv+kh rpkxvl5bj9dk s4a 9,ns?

  Which of the following correctly descrm0i*1eiyevyu m8xsh z* bb942 ibes photosynthesis or respiration?

Many enzymatic reactions happen as pamr -8i9ktwgt0 thways involving multiple steps and multiple enzymes.k-m irw t08tg9

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

  Which of the following best describes the inhibitor in the imagiwiu hn)- 0ac*ny j(8de below?

  Which of the following statements are tr1ikc+ pei,1 5y-vvxztue regarding regulation by end-product inhibition?ik1v ,tz+evy-1pci5 x
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 e- tkz9lgu:8b +vq)y vlysozyme enzyme. The darkened structure in black is the substrate and is bound at the actl tu+:e-q8g)vy zbv9kive site.

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

The equipment below can be used to study the effecttp nla1e.g- s2 of temperature on the activity of the entn.- l1ag2p sezyme 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 debh7a(ws3m +t 0lxjs vos*s7z/ scribes how enzymes interact with substrates to cat( sh037bv/jaoslsmw7zx+s*t alyze 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 enzyme0gco+ cb+8 t2y(5v*vw k hzu:efjr6oa catalysed reactions can be measured.

  How does denaturation chanppq9fhcocu 5 (zsqd7 3+2 uq9xge the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the fo38n oi+o vq..unjkne,llowing statements are truqunno .,o +i n83ekvj.e?
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 or7f v:is r:*4uz7vh elslbf: q4 endotherms from ectotherms that have fluctuating bode 7hl:fluv 4q:f:s 4vsribz* 7y temperatures?

  A metabolic pathway that converts threonine to 1w -iv).xo wgbfi8pn,the end-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 pathway1.p xoi,-gw) ib8vnfw .
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 0 4r,ntfwbc 7ap/n7zfincreasing pH on the rate of an enzymatic reaction. What is occurring during t7n/b,cf t 7afn0rzwp 4he phase labelled section X in the graph?

  An experiment tests the effecsd kzpuoxo4 ;:iy:4o/t of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent variables in this expex 4zoo;/ys:pk :oiu 4driment?

  The diagram shows the pathway that converts threonine to isoleucine.u+rkk 8 8( ixarl;sk(o



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 activitgax6 2k/c;m edy was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-axis)m xca6 ;g/dk2e.



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. Whm3dabl (,8jmj/ 8nr ifich of the following is the best way to keer, b 8lmnja/jd38mif(p enzymes active for a longer period of time?

  Which of the following del34dj-l r no4bscribes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A (f4:krg3l5jtp 5/hh ztw5 kyxstudy was carried out to d5 4hk /(p xj:5tgw35zhtrklfyetermine the effect of increasing 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 the rate of reaction of an enzyme with l(s vfp *x)a1lincreasing 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 the activity of the enzyme with no inx1l(a f*)p lsvhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a turnip root into small cvn1cao3 fs/n2k7lm/e ubes. 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 e7f3o masn 2k//l1vncliquid 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 enzndx 8n9 sk:gb9yme HMG- CoA reductase can lower the production of cholestern:nkd bx 98g9sol.


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 2jls)95zkw0kfba z;kin 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 reactionsp5od pq5o6 ag-+ez d;enid1i: in the classroom and were given an experiment which demonstratog-e 6za ie ;nop:51qpidd5d+ ed 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 v to.08l i)mnyyo( olqc5et0;on the efficiency of lactase activity is tested. Which is;8 e( yt05.o0oy) imncqvltol an appropriate dependent variable for this experiment?

  A study has been conducted on the activity of a specific lactahm-vjwh xas)l1hx ::;se (Bg10), analysing the effect of pH, temperature and glucose :;xh aw1:-)hl jmxvhsconcentration, 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 find new drugs ir6 ssid0si1 oxv04pex41b1pfor treating patients with malaria4 61s iopdi1 vre4bxixss100p. Describe how anti-malarial 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 of an enzyme affects the ,2;vxg41jqwlvg7u qd rate of reaction.j4 7g2,qxvqv 1; wuldg
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 brokeneq*7m) vy hus1 down or synthesized through metabolic reactions. Which type(s) of metabolic reactiv1s)mh equ y*7ons are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzys355 1pwt(aey 9odbs t7uo f5sme catalyzed reactions can be measure37 tu5oytebwdfs9(1p5s as5od.
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 contra:jndds3s h3ejl-- hv k5 gl-4est intracellular and extracellular chemical reactions, given one ejgd 3-h4lh5e3ld -j s nv:sk-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.