Which of the following macromolecules so0 oc+(.uz5 +fol dup0-jsfadescribe a typical enzyme?

  What type of reaction is ph,sxb2s 0h7xczf(jq2r9 gonq9otosynthesis?

  What is the substrate fp6v bzxws+-n;ea* n n7or the enzyme lactase?

  Which of the following stages of cellular respiration takes place in the c96eghy /x,uhzovv8 h; ytoplas8y zxh u;v9,g 6ohvhe/m?

  Which of the following would not be useful in detjmm. :l,f xbh/ermining the rate of an enzyme-catalyzed :,bm /xjml.fh reaction?

  Which of the following processes mapk.0 56ccu yr*nn viu,y be described as catabolism?

  Which of the following statements is best depicted by the figunouhot3zqhx02 w; gl:(rin oi 79j6l(re below?

  Which statement abou4dh / b 9xkis2eyn+:njt enzymes is not true?

  Which of the following graphs best illustrates the relationship between temp:w61p6mkw cf serature and the activity of kf 6w mwc61s:penzymes such as lipase?

1.Sketch a graph to show how increasing concentrations of substrate aff 6no(5z,o-vd:p3 lqwqkn-uu rect enzyme acuzow(p n:r 63-,5 ndv q-lqukotivity.
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 outlininoha) /:pihhfn98aazg 0 zvz(, g the Calvin cycle a/pah0z:8 n9 izz,f)ahhv g(ois shown below.

The image below shows the catalytic site of an enzyme. The +x+rof a u n*gor5l.wxm9;8szsubstrate is shown in black and is bou rr;*o 9aslo8+ 5mx.f unzwx+gnd 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 pathwaysz /tbvf7 xejw3/tn2:e shown below? Letters represent various 2n xztf:j b3/v7/weetproducts of individual reactions.

  Which of the following describes the role of inhibiy 9eyzh (/uajf 971(qq+xlcif tors in enzyme-catalysed reactio7yj/h+1 yl9eqqz fcu ai9(xf(ns?

  Which of the following correctjso2.sm2 3bzjcxlq hrh/6 26a ly describes photosynthesis or respiration?

Many enzymatic reactions happen as pathw w(vc+cwsa(7p ays involving multiple steps and multiple enzym+ (7cw wacpvs(es.

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

  Which of the following besz2p o( tujh mhd q2s;8ojo7h,-t describes the inhibitor in the image below?

  Which of the following stat:fhl 5x)h6iz;i zdj2d ements are true regarding regulation by end-product inhibitz: dzh2 lhiif6;5 )jxdion?
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 pc+j e a09 e(hkddow 1t0an)i464co9 uzfa+ioenzyme. The darkened structure in black is the substrate and is bound at ho0 npfaz4ii a1c46ad utw +oeo9jk+9(e0 dc )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 activu1-i k-ip dd9zn+hl7nity of the enzym7-pdh1lz + u- 9dnkinie 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 followi,5gqbk0j gd3zq fs2 f)ng statements describes how enzymes interact with substrates to catalyzsg 5,3qz g )qd0bf2fkje 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 enzyme catfeb176zl qfa g6t* :.d7qvvhralysed reactions can be measured.

  How does denaturation change theh e) c1vl9(hnhee6s:lc6ld * o properties of an enzyme?

  Enzymes play a role in cataly9m )kaccz .u/;2 dxurmsing reactions. Which of the following statements are tr.czuk)9c u/2 ax;rdm mue?
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 mfncf;ri z/ 3:e7g7 jmx/-cdkvammals or endotherms from ectotherms that have fluctuating bodyf n-;d/c jfixkve7 :37gzrc/m temperatures?

  A metabolic pathway that converts threonine to the end-r nek:sem6q z2m6c6o;v 6f1dd product isoleucine consists of five reactions. Threonine is converted to various intermediate products sequentially by different enzymes before it is converted to isole2v1 nmc66 s6eq6 :erkofmd;dzucine 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 dc 5gqanhd/(j;0j2vqwy r*;i increasing pH on the rate of an enzymatic reaction. What is occurring during the phase labelled section X in the gr dj*dijwrv;a/ c;q0y 2(nh g5qaph?

  An experiment tests the effect of changing subszg73th/ b)i- )2lq+smparle htrate concentration on an enzymat msb/2halp+)e t)h qg7ir 3lz-ic reaction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts c d5* o(8cgwrpch*(zk 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 i4fle 0iat :hnx*4dwsculz443 tk*vd6ts activity was compared with that of a free enief04l xudw:vn al4*k4 z6htds 4*t3czyme in solution. The graph shows 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 denatured. Which of fkn0 chfz92i 6the following is the best way to keep enzymes a26ihf fkzc0n 9ctive for a longer period of time?

  Which of the following f1jaius 8kd/a9g + 3atdescribes some types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomach. A stuoxu:h) .x.5 aq xbrmu(dy was carried out to determine the effect of increasing substrate concentr( )rh5qo:u. ux. xmxabation 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 rq ,z;s c/1esnreaction of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reactisnes ;1rq/z, con, 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 rou2px ng 9;r,o2 zybs0bot into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml 0 bb92 z ysr;p2ogx,nuwater and used a blender to homogenize the turnip root. The homogenate 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 thx gbv :xl:i-8s 585bm0rjfjske enzyme HMG- CoA reductase can lower the production :850xsslxi fvmk g rj5-jbb8: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 denaturatio9;u y:ox c8sgxn?
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 the9x9g,fi mozx/ classroom and were given an experiment which demonstrated the effx/zfxmgi 9o9, ect 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, them2-he me-vrkww3 kv9+nw1 pq/ effect of increasing temperature on the efficiency of lactase amq21 wwk 9/p k emvv+nh--er3wctivity is tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on thel5ckj s,+hhc w ri)6,d activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactose+,5lwr,ijckhc 6) s dh-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 pat/ 9r cj:;bqbthjv pl27ients with malaria. Describe how anti-malarial drugs are being discovere;vbq7c 2jt:b9r hplj/d 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 concentrati ef2,;luhyrnx,4d cfuwivd117wr : a0on of an enzyme affects the rate of reactif w1ufx0dy1d,ve2 4,7lr ui;ar: nchwon.
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 xpzjkw9ei 9gn l4w4jsa)a(0 3 synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation reacwxgw49l e3a)znpa4kij9 (j0s tions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of9yq fy,x,q1 qpf x69vo enzyme catalyzed reactions can be measur6oy qfq9,9 pvy,1qxfxed.
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 extracelf)zii// q*c 4cj v:pux7chb;wh c0t;flular chemical reactions, given one example of eac:t;4/w) jpz7xh0b fc;iqc vch/* fuich 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.