Which of the following macrub*;pn:uh+ t fomolecules describe a typical enzyme?

  What type of reaction is photosynthesis?8m v t*o.j2 t4iyc,t. ; cydolg2(jioo

  What is the substrate for the enzyme la:+h,39kdoc fm4 pi jbnctase?

  Which of the following stages of cellular resw6/ar )r kzgsn 95l8depiration takes place in the cytoplasm 5/kwl ersrn)6gd z89a?

  Which of the following would not x w+ 5uywlv ick/g:t-0be useful in determining the rate of an enzyme-c5 git /x k0cv-w:wlu+yatalyzed reaction?

  Which of the following proces).b2cqn wcm+y 97pd xkses may be described as catabolism?

  Which of the following statements i (2 f8wj1oswvls best depicted by the figure below?

  Which statement about enzymes is :dn z2yw 3x78 ry2nbginot true?

  Which of the following graphs best illustrates the relationship betwe; 3mxra yp(xt 1w4:fnren temperature and the activity of enzymes such w:fx4 nm1x; a rtry3(pas lipase?

1.Sketch a graph to show how)6bp ncqr1b/e increasing concentrations of substrate affect enzyme activity. 1qp/rb)c nbe6
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactionsi u9xt un:/t:s. A diagram outlining the Calvin cycle is s:t9 i :nusxtu/hown below.

The image below shows the catalytic site of an enzyme. Thxs- dyoyf.w28qt l5u- e substrate is shown in black and is bound to the active sitel- uy.-wqo 2fyds 58xt.





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 b 5zh*1.bq)i e6tdy(dvnrk t( of the enzyme catalysed metabolic pathways shown below? Letters represent various products of dh5ttbq v6z*(yd1 b.eki(n)rindividual reactions.

  Which of the following describes thk 4 d4ije/po 54qkn*t9wl)qfee role of inhibitors in enzyme-catalysed reactionqw4p kqe4/t5l4 feo i9k)nj*ds?

  Which of the following correctly describes photosynthesi7vfjfg vj- 0i9s or respiration?

Many enzymatic reactions happen as pathways involving multiple swn x1l2ae n6v8teps and multiple enzymes vnlw8a xe6n21.

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

  Which of the followih ps20u sxd,t3ng best describes the inhibitor in the image below?

  Which of the followinht021hnip gd2h 6* aong statements are true regarding regulation by end-product igh02 dn6h1*pn hio2atnhibition?
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 enzyme. The4wg+ewvi6:h;5wvddvk c +tg2e 7 k5zw darkened structure in black is thve7d de4+vi tg5h6+kcw wwvz:gk w;25e 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 temperature on the activi9-nc4rn)yis0 d8rqg*rrl/ yyty of the enzyme amyd* glrqr0 y)r-cyn /94rinys8 lase.



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 w 0xvxvup8db-7 ith substrates to catalyze reactib8vpx7 d0 uxv-ons?
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 can be mex m f:j(s atl,v4mal;9asured.

  How does denaturation chw5owz5m 3 ans4ange the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following53la edz+v jb0 statements are true vad3z j0+bl5e?
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 tth31pt4)sa kmvno,)s hat separates mammals or endotherms from ectotherms that haveah)4vk p3)t notss, m1 fluctuating body temperatures?

  A metabolic pathway that converts threonine to the eng 4wnadw-*dwfv9 n1d/d-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 1wvd4- /nn*dfww ga9dpathway.
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 the rate o9 w7gzm)y m0s/kfs(-y7w ldtrjdb;+ w f an enzymatic reaction. W(fdwmjk97-; m0/ wr wsy)yzg+ d7bls that is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate :bage ( o/bze ye5c0t1 sy/5brconcentration on an enzymatic c51b a5 bee0 yeysoz/(tg/r:breaction. What could be the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threonr*uby/lk snr ;8(+m mjine 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 a j54lp :zxjwofyd8e32nd its activity was compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying3:4 j8y e5fdpzo2xjlw 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 off)5m arnkxz17 q;l0xu the following is the best way to keep enzymes7rka xx1um0 l5)n;qzf active for a longer period of time?

  Which of the following describes ,p-p naq bc,m+)by 2jwsome types of extracellular enzymes?

  The enzyme pepsin hydb6u6q+u;qr3 a)k osqi rolyses proteins to release peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentrabir 6s+k )o auq36q;qution 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 incumlaw, ehot w,)+88f zreasing substrate concentration. Similar concentrations of chemicals A,+tlu)amw 8fh8 , ezwo, 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 a kz9n wiar-b:)o*ud9a ctivity, a student 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 the liquid extract was stored in a unbr* doa9 k)9a-iwz: 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 4mtqm 7 dtn:g/is shown below. Inhibitors to the enzyme HMG- CoA reductase can lower the production of cholesterold/t gntm4m 7:q.


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 arue)amg m:*+lr e involved 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 reactions in the classroom and were givei4 k, +sgecxr5n an experiment which demonstri,e+54grk cx sated 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 s67rc:ok lifou q01(ytemperature on the efficiency of lactase activity is tested. Which is an appropriate dependent oi (q7y:u10rlko6cs fvariable for this experiment?

  A study has been conducted on the activity of a specific hjo2c4zu/a8ey1wnb b: e go9n;l7h q0 lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactose-o1;7wygluo 2hj /48 ze0an n9ecbbh:qfree 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 ny+q hr z ):km+kk.jww.fyum.7 ew drugs for treating patients with malaria. Describe hk:hmy+.wq f.um r)zk7 j+ .kwyow 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 *+tuf67tf0 kj/gkhwbconcentration of an enzyme affects the rate of reactionf+ 0 j6kbfkutg7t/hw* .
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 cgozbv6.6:wy )2z x7q uunqf+0jgzv(through metabolic reactions. Which type(s) of metabolic reactions are condensation reactions .qvxwz: qzu6)g 7vgn02jc+f ou6y(b z?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyzed reactions c* v6ytimu(:stdkg +s -an be measured6 tt*iu: m(sgk -+svdy.
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 chemical reactions, -9wg.uzy** elwi 6 umygiven one example of each type of rz*6e -iug. w wuy*mly9eaction.
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.