Which of the following macromolecu))uz k;yk4k+4loee xules describe a typical enzyme?

  What type of reaction is photosynthesis?gd1v,kh1b mejbdk 1;+

  What is the substrate for the.)qeud 9oom.u+,fj vam2 *,s ccupno- enzyme lactase?

  Which of the following stages of cellular respirate0 .s ;-zq x9) h1prix0ntluojion takes place in the cytoplasm?;p)xxnu19t 0.iesqo0z-l rh j

  Which of the following would not be uskn 8,.d3r *l) gyo yz:p)oeqqceful in determining the rate of an enzyme-catqdy,q:or*z 8enoc.yk) )3l pgalyzed reaction?

  Which of the following processes may be descr tzz/6p kcsgqf f au*69ryt41,a43lx libed as catabolism?

  Which of the following statements is best depicted by the figure be8.s /n n6ua0sb(hy nzllow?

  Which statement abouoyj *y6s0xh2 bt enzymes is not true?

  Which of the following graphs best x5g qgao)b( h0;:vstq illustrates the relationship between temperatuvo t;hg05abq:q s xg()re and the activity of enzymes such as lipase?

1.Sketch a graph to show how increasing concenthn-p9p b+b i6 2kxeg+grations of substrate affect enzymek2 +6e+px9-bbhgn i gp activity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series offk(i1bfco:ee3 9ct5x enzyme catalysed reactions. A diagram outlining the Calvin cyef1 i:c5 otf 39bk(cxecle is shown below.

The image below shows the catalytic site of an z39hvxd 7sqpt( g i23henzyme. The substrate is shown in black and is bound to the ac(h239qhz ps3g 7vdtxitive 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 enzyme4* yr+wg++zcn mps8a 6gt ff1x catalysed metabolic pathways shown below? Le*mfz+ gy6pr8w txgfs4++ 1can tters represent various products of individual reactions.

  Which of the following describes the role of inhsq/d8aa3 0*ldgws o4 8uv4bdo ibitors in enzyme-catalysed reactio0/bawa s 48ovgo3l* ddu4ds8qns?

  Which of the followiv8 agg c)d14p9kzd4cfs2o d,u 8m oo4wng correctly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathways involving /j tuzboz0pm:.vy sg(e8g9s.multiple steps and multiple jv gy.(mzbu. o0 8gtsz 9p:e/senzymes.

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

  Which of the following best describes the inhib1jl9lz, k:6h6rliek hitor in the image below?

  Which of the following statements are true regarding regulation by end-prodyyks x (x 6)*vpukol*7uct inhibitiolk) ovx7psy*(y* xu k6n?
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 enz swbr(yzi vw; dh8xyc9z 6.; zauz1h++yme. The darkened structu+azxhr8 w.hd9zv +z6b; ;iywcz(yu1sre in black is the substrate and 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 temp06 4wl69 ikech5 a3r;tx.k 9srl fx1rqkergi/erature on the activity of the enzyme e.r5r 09qklwxrai1gr ie 6x94 h/ skl;f63kctamylase.



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 hk-j.nqq b( j29ps jg:substrates to catalyze rea9j-s.n pj qbq:j2kh( gctions?
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 qbo7;e *7 +ojji;b0+zcxp aomcan be measured.

  How does denaturation change the prxe;w7) m,wkwt operties of an enzyme?

  Enzymes play a role in cat95f 7ry1snwex 2/dtnlg 0gu :salysing reactions. Which of the following statements are1x5l7: es9u tfnrn0/2swgydg 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 characteristic that separates mammals or endotherms ,y (+ isdr5u c6bhb 9tgylm6zui(2f+ufrom ectotherms that have fr+gm6h(i ldybt ui b 2fu,u5 z(c96+ysluctuating body temperatures?

  A metabolic pathway t rbdcnn(c um( b*2+ w/vj*x3x.nmhtjf6m ;/othat converts threonine to the end-product isoleucine consists of five reactions. Threjdnx6ucm/ ht;n2m .+vb* nr(bw *3(mxc/jfto onine 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 y62 z9.va .*cok vvgflof increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the gralazv6c.*k2gv ofy9v. ph?

  An experiment tests the effect of changing substrate *,db(k j6az/zt o:vkxconcentration on an enzymatic reaction. What could be the independent and dependent variables in this experimentdz :ba*,t 6jov(zx k/k?

  The diagram shows the pathway that converts threonine to isoleuci r( mn)w77,mbtdx6y alne.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobilized on a j h)e;dqpu a2d y6vn)rh7,r 3b(ozj 5dkn2l0c matrix and its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with vu 6adj2nzl r5p(dyoe)23rjd ;,q h0kvc h7nb)arying 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. Wnc2ry q9d f7;opgo2 k/hich of the following is the best way to keep enzymes acr/ ; ogk9n2q7d2fco yptive for a longer period of time?

  Which of the following describes some types of extracellulac(.lze (a u8ng jbd1r7r*mf) er enzymes?

  The enzyme pepsin hydrollzp+lqz. d ,/jyses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasinz lzj l.+d/pq,g 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 inct 2gyn;8lcty,oo:z6r vjwd ,3 n4 tx7yreasing substrate concentration. Similar concentrations of chemicaltrwx ln:, ;,ctv 2 oy48dyo3y 6jz7gnts 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 root into small cc,y;n-iue .2f - u)sqj *njkkrubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The homon2si -;nuq r jkej*y,fk) u-c.genate 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. Inhibitors to the enzyme HMG- Cw5zs9 -y 68zq rk7tefzoA reductase can low58-rqzz6tsze 9f7 kw yer 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 involved in jb : v w:xo k0:ohqmo),u9g:d l7emuj,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 classroo7nt 95mz ;;g6whrr/ffirh a xiowv3 :-m and were given an experiment 7 -/h:w;g3 9fh ;6rwf orvx ari5mtzniwhich demonstrated 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 incerfn g+1 -gh0mreasing temperature on the efficiency of lactase activity is tested. Which is an appropriate dependenng+0ge- fm hr1t variable for this experiment?

  A study has been conducted on the activity of a specific lacti)nzp 5tby n1g/;1lmkase (Bg10), analysing the effect of pH, temperature and glucose concentration, as i zgn k5)1nl/;mibty1 pt 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 drugo/s ixunl04ef vmmou4/ 3l2a, s for treating patients with malaria. Describe how anti-malarial druga4s/i uom,0fx /lunem24o3l vs 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 concentr , ij1npdyvli2t69n9 ky/vt gm; bv60qation of an enzyme affects the rate of reaction.v6j9;vqy 1y9p tn blgivk60, m2tidn/
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 syntheoiomk( j 6wf9j,/9 gvie,2x wbsized through metabolic reactions. Which type(s),j9vbofgw9/xei 6wom k2(, i j of metabolic reactions are condensation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the sg*.wyqu n, h.4*kvwq7lv,qnrate of enzyme catalyzed reactions can be measurq.*unls ,.vnw y7q,gv*4h kwqed.
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 contrasow a7 vk*3uyg/t intracellular and extracellular chemical reactions, given one example of each type of k7w/*oaugv y3reaction.
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.