Edexcel biology JUNE 2015 scientific article questions

POTENTIAL QUESTIONS

AND ANSWERS FOR THE

SCIENTIFIC ARTICLE OF

JUNE 2015

[Drugs in sports]

Edexcel Biology Solutions [email protected]

1

QUESTIONS AND ANSWERS FOR THE SCIENTIFIC ARTICLE OF JUNE 2015 DRUGS IN SPORTS

Table of Contents Background Revision Topics ........................................................................................................................................................ 4

Questions and Answers ................................................................................................................................................................ 5

1. Why do athletes take drugs? (Paragraphs 2-4) .............................................................................................................. 5

2. What ethical principles can be applied to considerations of the use of performance enhancing drugs in sport? (Paragraph 35) ................................................................................................................................................................... 5

3. How would you define the term doping in the context of performance enhancement by athletes? ............... 6

4. What are the hazards to athletes of using drugs to enhance performance?............................................................ 6

5. All elite athletes competing in international events may be routinely tested. How is the testing for detecting cheats carried out? (Paragraph 5) ............................................................................................................................................. 6

6. What do you understand by therapeutic use exemption? (Paragraph 9) ................................................................ 7

7. What criteria are in place for the granting of a TUE? (Paragraph 10) ......................................................................... 7

8. The prevalence of doping in sport seems to be currently increasing. Suggest why this trend is so widespread across sports. .................................................................................................................................................................................. 7

9. What criteria must be in place for a system of regulation to be effective? ............................................................... 7

10. How are the criteria enforced prior to testing and post-testing? ................................................................................ 8

11. Suggest why some substances are prohibited both in- and out- of- competition. (Paragraph 6) ....................... 8

12. How does the consumption of alcohol above certain limits affect the metabolism and behaviour of athletes? (Paragraph 7) ................................................................................................................................................................................. 9

13. Caffeine is the most widely consumed central nervous system stimulant. What effects can this substance have when it enters the body? How do these effects impact the health of athletes? (Paragraph 7) ............................ 9

14. How does caffeine affect athletic performance? ........................................................................................................ 10

15. What role does WADA fulfill as an anti-doping agency? (Paragraph 39) ............................................................... 10

16. The rigors of sport means that professional athletes are at high risk of joint injuries. How may such injuries be treated? ......................................................................................................................................................................................... 10

17. What are the advantages of using keyhole surgery rather than conventional surgery? ...................................... 11

18. Describe the uses of X-rays, Computed Tomography (CT) scans, magnetic resonance imaging and Functional Magnetic Resonance Imaging (FMRI) in the diagnosis of sports injuries ....................................................... 11

19. What do you understand by the term haematocrit and what group of athletes benefit from a high haematocrit? (Paragraph 19) .................................................................................................................................................... 12

20. How can a high haematocrit be achieved legally? (Paragraph 20) ....................................................................... 12

21. What is blood doping? Distinguish between autologous, homologous, and heterologous blood doping. (Paragraph 19) ............................................................................................................................................................................. 12

22. What risks are associated with blood doping? (Paragraph 19) ................................................................................. 13

23. Are elite athletes born or made? (Paragraphs 40-43) ................................................................................................. 13

2


24. What are diuretics and why do athletes use them? (Paragraph 15) ........................................................................ 13

25. How do diuretics exert their effects in the body and what side effects may develop from the use of such substances by athletes? (Paragraph 15) ................................................................................................................................. 14

26. How does the International Olympic Committee (IOC) promote fairness in top level sporting events? ........... 14

27. When athletes suffer injuries they may use Non-Steroidal Anti-Inflammatory Drugs (NSAIDS). Why do athletes use these drugs and what are the risks involved in their use? (Paragraph 12) ................................................................ 14

28. What are opiate analgesics, what effects do they have in the body, and what are the problems associated with the use of these drugs? (Paragraph 13) .......................................................................................................................... 15

29. Cannabinoids are the most widely used illicit drug in the western world. How do these drugs exert their effects in the body? (Paragraph 4) .......................................................................................................................................... 15

30. Why do athletes use these cannabinoid drugs and why are they banned? .......................................................... 15

31. What are stimulants? Why do athletes use stimulants and why are these substances banned during competition. (Paragraph 16) ..................................................................................................................................................... 16

32. Amphetamine is a potent central nervous system stimulant. Why do athletes abuse amphetamine and what are the risks involved in the use of such drugs? (Paragraph 17) ......................................................................................... 16

33. Give a brief account of synaptic transmission in cholinergic neurons. ................................................................... 17

34. Why does having a high proportion of fast twitch muscle fibres suit sprinters? ...................................................... 17

35. Construct a table to compare slow and fast twitch muscle fibres. ........................................................................... 18

36. Why does having a high proportion of slow twitch muscle fibres enhance performance in endurance athletes? ........................................................................................................................................................................................ 18

37. Construct a flow diagram which summarises blood clotting. .................................................................................... 18

38. What do you understand by the term generic with respect to drugs? (Paragraph 21)....................................... 19

39. What do you understand by the term anabolism and what are anabolic agents? (Paragraphs 22-24) ........... 19

40. Why do athletes abuse anabolic agents and why are these substances banned? (Paragraphs 21-24) .......... 19

41. Female steroid hormones do have anabolic effects but in spite of this contraceptive pills are permitted to female athletes. What advantages could these pills give to female athletes? (Paragraph 23) ................................... 20

42. How does testosterone act in target cells? (Paragraph 22) ....................................................................................... 20

43. Describe the process of atherosclerosis. (Paragraph 21) ........................................................................................... 20

44. What are the characteristic features of hormones? .................................................................................................... 21

45. Paragraph 26 refers to a class of peptide hormones which were added to the IOC doping categories which already existed. Why were these substances added to the list and give an indication of the functions of these

substances? .................................................................................................................................................................................. 21

46. Three important terms are used to refer to molecules which bind to hormone binding sites or receptors. These terms are; agonists, antagonists and inhibitors. What do you understand by these terms? .......................................... 22

47. New illicit drugs are difficult to test for so there is an arms race between the use of new drugs by athletes and the detection of these drugs by the athletic regulatory authorities. What is the use of mass spectrometry in the

detection of new, illicit drugs being used by athletes and why is this detection essential? .......................................... 22

3


48. Describe an absolutist and a relativist ethical position on the proposal to set a maximum total red blood cell count for all athletes rather than measuring erythropoietin levels. .................................................................................... 23

49. What do you understand by the term homeostasis? ................................................................................................... 23

50. Paragraph 30 refers to the terms hyperglycaemic and hypoglycaemic, what do these terms mean and how does the human growth hormone promote hyperglycaemia? .......................................................................................... 23

51. Insulin can cause severe hypoglycaemia if not administered correctly and for this reason insulin is now only available as a prescription only drug. How does insulin lower blood glucose levels? ................................................... 24

52. Most biological systems use negative feedback mechanisms. Distinguish between negative and positive feedback systems. ...................................................................................................................................................................... 24

53. What is a gene? ................................................................................................................................................................. 24

54. Distinguish gene therapy from gene doping. ............................................................................................................... 24

55. How does protein synthesis take place in cells? ......................................................................................................... 25

56. How does erythropoietin express itself in target cells? ............................................................................................... 26

57. Suggest how it is possible for a single gene to have more than one variant. ......................................................... 26

58. Briefly discuss the process for presenting research results to the scientific community. ...................................... 26

59. What is inflammation? ....................................................................................................................................................... 27

60. Describe the process of inflammation (Paragraph 3) ................................................................................................. 27

61. What do you understand by the term gene mutation? (Paragraphs 40-42) ........................................................... 27

62. Many athletes who have tested positive for a banned substance, claim that they had only used dietary supplements. Discuss. (Paragraphs 32-34) ............................................................................................................................. 28

63. Why are sports inherently unfair? (Paragraphs 50-52) ................................................................................................ 28

64. How are negative and positive feedback mechanisms involved in the maintenance of a relatively constant internal temperature during exercise? .................................................................................................................................... 29

65. Therapeautic drugs go through rigorous testing and monitoring in comparison to dietary supplements. Briefly describe the phases through which the therapeautic drugs must pass before they can be marketed? (Paragraph

50) 29

66. Briefly indicate the uses of creatine in sports. (Paragraph 50) ................................................................................... 30

67. What is DHEA, and why did WADA ban this hormone? ............................................................................................... 30

68. Do you think that this scientific article contains reliable information? ..................................................................... 30

English Dictionary ......................................................................................................................................................................... 32

Dictionary of Biological Terms ................................................................................................................................................... 35

4


Background Revision Topics

- THERMOREGULATION

- MUSCLES

- EXERCISE AND JOINT INJURIES

- TREATMENTS FOR INJURIES

- KEYHOLE SURGERY

- IMAGING TECHNIQUES

- PERFORMANCE ENHANCING DRUGS

- HOW DRUGS WORK

- THE ETHICS OF PERFORMANCE ENHANCING PRACTICES

- HOW DRUGS WORK

- CHEMICAL CO-ORDINATION

- HOMEOSTASIS

- GENES AND MUTATIONS

- GENE SWITCHES

- SYNAPTIC TRANSMISSION

5


Questions and Answers

1. Why do athletes take drugs? (Paragraphs 2-4)

Whether competing in an amateur or a professional capacity athletes are entitled to medical

treatments, e.g. athletes with type I Diabetes mellitus may need regular injections of insulin.

However, both competitors and attendant doctors must be aware of the rules concerning

banned substances. Non-compliance can result in athletes receiving temporary or permanent

bans from their sport, and doctors may face litigation and the revoking of professional licensing.

Athletes may use drugs to enhance their performance, and in doing so they have an unfair

advantage compared to other co-competitors who are not using such methods of enhancement.

Doctors who collude with these improper enhancements, by providing drugs and treatments to

athletes, are contravening The General Medical Councils guidelines concerning the use of

banned substances and as such they are risking the loss of their registrations for professional

licensing.

Athletes carry responsibilities as role models for young people, and as such it is undesirable that

they should use illicit drugs, even for recreational pursuits.

2. What ethical principles can be applied to considerations of the use of performance enhancing

drugs in sport? (Paragraph 35)

The World Anti-Doping Agency (WADA), supports the dogma that the use of all performance

enhancing drugs violates the humanistic conception of what sport should be. This institution was

founded with the belief that athletes have the right to participate in doping free sport and that

doping endangers the health and the integrity of sport. WADA is an international body which is

responsible for coordinating and monitoring the global fight against doping in sport.

Doping is the most widespread method of cheating in sports, and since doping puts the health

of the athlete at risk then this is a good ethical reason for banning the use of performance

enhancing drugs from sports. Some ethicists argue that safe drugs should be permitted whatever

their effect on performance e.g. authorities could set a safe limit for red blood cell concentration

and any athlete exceeding this value would not be allowed to compete.

The use of such drugs is contrary to the spirit of fairness expected in sports competitions.

Unfortunately, the spirit of sport cannot be objectively measured. Doping shows a lack of respect

towards other competitors and also a disregard for the rules and laws surrounding competitive

events.

Sports ethics foster fair-play and honesty.

6


The GMC guidelines are explicit concerning doctors who aid and abet drug abuse in sport but

unfortunately situations of damage limitation which are difficult to arbitrate, do arise.

Also some of the drugs used in doping by athletes, are illegal.

3. How would you define the term doping in the context of performance enhancement by athletes?

In competitive sports doping refers to the use by athletes of banned performance enhancing

drugs. The term is widely used by organizations such as the International Olympic Committee (IOC)

that regulate sporting competitions. Doping is defined as the occurrence of violations against the

anti-doping rules set by WADA.

4. What are the hazards to athletes of using drugs to enhance performance?

Most drugs and hormones used by athletes to improve performance, can cause severe adverse

effects when taken for non-therapeutic reasons. In addition, if the drugs are administered by

injections then there are risks associated with the misuse of syringes.

Drugs obtained through underground networks may not have been manufactured to the

standards required for licensed products. Such drugs may be contaminated, unsterile, have no

active ingredients and may contain undeclared substances.

The internet is currently a source of many drugs from unknown origins placing athletes at risk from

toxic contaminants.

The use of nutritional supplements puts athletes at risk from an inadvertent positive drug test.

It is proposed in some quarters that athletes should have passports which are records of the

athletes physiological profile over set time periods during their career. This would be a powerful

deterrent against doping.

5. All elite athletes competing in international events may be routinely tested. How is the testing for

detecting cheats carried out? (Paragraph 5)

Under established doping control protocols each athlete provides a urine sample which is divided

into two portions in sealed containers carrying unique identifications and designated as Sample

A and Sample B. When a Sample A showed the presence of a banned substance the athlete can

request the analysis of Sample B, so the B sample helps to confirm a violation of the anti-doping

code while simultaneously protecting the rights of the athlete.

Blood samples are regularly taken and winners of events are always tested, as are any athletes

showing significant, unexplained improvements in performance.

Samples may be re-tested at later dates.

7


6. What do you understand by therapeutic use exemption? (Paragraph 9)

Therapeutic Use Exemption (TUE) allows athletes who need to use medications for medical

conditions, to use these medications both in and out of competition. It applies, for example to

diabetics who need insulin and to asthmatics using beta-2 agonists.

7. What criteria are in place for the granting of a TUE? (Paragraph 10)

The criteria for the granting of a TUE are;

- That the athlete would experience health problems if the prohibited substance or method was

withheld.

- That the use of the substance would not produce a significant enhancement in performance.

- That there is no therapeutic alternative to the use of the prohibited substance.

8. The prevalence of doping in sport seems to be currently increasing. Suggest why this trend is so

widespread across sports.

One reason may be the considerable pressure on athletes to deliver medals with winning

performances.

In team sports there is pressure on individual athletes, within the teams, since success depends on

the performance of all the members of the team.

Significant financial gains may be achieved from success in major sporting events.

There may be a failure to understand that if one athlete chooses to dope, then this action will

impact all competitors in the competition. This results in a knock-on effect as other competitors

perceive that co-competitors are doping and getting away with it. Overall, more athletes may

then be inclined to dope.

Doping creates an inbalance in competitions.

The ease of availability of many prohibited drugs may also encourage doping.

9. What criteria must be in place for a system of regulation to be effective?

- The system must meet a number of well-defined criteria and the system must be equitable.

- The regulations must foster the human rights of the competitors, coaches and medical

professionals involved.

- The system must be proportionate to the dangers it seeks to avoid.

- The system must be well funded and unimpeachable.

8


10. How are the criteria enforced prior to testing and post-testing?

Pre-testing, all athletes registered in the Sports Councils Registered Testing Pool must apply for a

TUE prior to using a prohibited drug or method. This regulation also applies to athletes who are part

of the International Federations Registered Testing Pool.

Registered athletes are advised of the TUE requirements in writing.

Post-testing if an athlete is tested and the laboratory report contains an Adverse Analytical Finding

(AAF) the Sports Councils Anti-Doping Unit will request the athletes up to date medical file, which

is then submitted to the TUE Committee together with a TUE application.

If an athlete is unable to prove legitimate use of a prohibited substance or method then the AAF

send the case to a Disciplinary Hearing Committee.

11. Suggest why some substances are prohibited both in- and out- of- competition. (Paragraph 6)

Some drugs can create long-term changes in the body, either by increasing physical

performance or by damaging the body. Such substances e.g. anabolic agents, are banned

completely. Other drugs have no permanent impact since they are eventually excreted from the

body. These drugs e.g. stimulants, are banned during competition only.

Such substances include all chemicals not approved by any governmental regulatory health

authority as being suitable for human therapeutic use. Examples of such drugs are those

undergoing trialing, or drugs which have been discontinued.

Anabolic agents are prohibited when they are metabolites or have a similar chemical structure or

biological effect to natural metabolites. This category includes prescription testosterone creams

or injections, and the use of anabolic substances e.g. DHEA in dietary supplements.

Peptide hormones, growth hormones and mimetics form a category which includes

erythropoietin- receptor agonists and any substances which promote erythropoiesis.

Growth factors affect muscle, tendons, ligaments and protein synthesis. Examples of these are the

Human Growth Hormone, (HGH), growth- hormone releasing factors, and the insulin- like growth

factor- 1 (IGF-1).

Chorionic gonadotropin (hCG,) the luteinizing hormone (LH) and their releasing factors are only

prohibited in males.

Beta-2 agonists are drugs commonly used to treat asthma by relaxing the muscles which surround

the bronchi and bronchioles thus opening up the airways and giving better air flow and

oxygenation of the body tissues. They are decongestants. These drugs are banned because they

9


confer the same advantages as powerful stimulants or when administered into the bloodstream

they have anabolic effects which increase muscle size and reduce body fat.

12. How does the consumption of alcohol above certain limits affect the metabolism and behaviour

of athletes? (Paragraph 7)

Metabolism.

Alcohol promotes water loss by depressing production of the anti-diuretic hormone by the

hypothalamus. Urination increases, and in addition to the water loss there are significant losses of

magnesium, potassium and calcium ions. These ions are essential for nerve and muscle action,

co-ordination and the maintenance of fluid balance in the body. In addition alcohol reduces the

absorption of essential vitamins such as thiamine, folic acid and vitamin B12. Alcohol can raise

blood pressure.

In athletes, alcohol use results in decreased exercise time to exhaustion and decreased

performance. Alcohol causes vasodilation which promotes heat loss and a lower body

temperature.

Behaviour

When athletes use alcohol their precise, fine, motor control is impaired but the athletes feel that

they are less tense, more relaxed, and have less hand tremor when using alcohol. In reality they

are experiencing decreased eye-hand co-ordination and impaired judgment. Alcohol

intoxication puts an athlete and others at risk.

Alcohol above a threshold is prohibited during competitions.

13. Caffeine is the most widely consumed central nervous system stimulant. What effects can this

substance have when it enters the body? How do these effects impact the health of athletes?

(Paragraph 7)

Caffeine is easily absorbed across the walls of the stomach and small intestine. It is circulated in

the blood and exerts stimulant effects on the brain. High concentrations of this substance mobilize

intracellular calcium ions. Caffeine increases energy metabolism but also decreases blood flow

to the brain. Caffeine activates adrenergic neurons of the sympathetic nervous system and also

affects the release of dopamine. These effects are due to substances called methylxanthines

which are present in caffeine and which are cardio-stimulants. Blood pressure and pulse rate

increase. Fat stores are mobilized and fatty acids are released into the blood stream. The

methylxanthines act on serotonin neurons.

The psychostimulant effects of caffeine are subtle and not easy to detect. Certainly the effects of

caffeine on learning, memory, vigilance and fatigue are due to the methylxanthine components

in caffeine, and are dose related. Small doses and temporary use do not usually present serious

10


risks. However caffeine is a diuretic and may cause dehydration. Caffeine intake increases anxiety

and reduces sleep in sensitive individuals. Regular evening use of caffeine may gradually deprive

the body of proper sleep resulting in lack of energy and fatigue. Since caffeine promotes an

increase in stomach acid production it may irritate stomach ulcers. Eventually after long term use,

the body develops a tolerance to many of the effects of caffeine.

14. How does caffeine affect athletic performance?

The role of caffeine as a performance enhancing drug has produced controversial and

conflicting data. However, it is agreed that caffeine does not appear to benefit short-term, high

intensity exercise such as sprinting, but it can enhance performance in endurance sports.

Caffeine can exert beneficial effects on muscle. Glycogen is the main fuel for muscles and

exhaustion occurs when glycogen is depleted. Fat is also a respiratory fuel which muscles can

utilize, providing glycogen is present. Caffeine mobilizes fat stores and encourages working

muscles to use fat as a fuel, delaying the depletion of muscle glycogen and prolonging the

exercise period. This glycogen sparing only occurs at the beginning of the exercise when caffeine

may decrease glycogen utilization. The glycogen saved at the beginning of exercise can be used

in the later stages of the exercise. The effect on performance was that athletes had a longer

period of exercise before exhaustion occurred.

Caffeine may change the perception by the athlete as to how hard the athlete may be working

during an exercise. When athletes used caffeine they were less inclined to show fatigue during

exertion.

15. What role does WADA fulfill as an anti-doping agency? (Paragraph 39)

The World Anti-Doping Agency (WADA) internationally promotes, co-ordinates and monitors the

fight against all forms of doping in sport. WADA fosters a doping-free culture in sport and combines

international resources designed to enhance, supplement, and to co-ordinate existing efforts

aimed at educating athletes as to the adverse medical effects of doping. WADA actively

reinforces the ethical ideal of fair-play and sanctions those athletes who cheat. WADA also

fosters national anti- doping programmes. WADA publishes a full list of prohibited drugs every year.

16. The rigors of sport means that professional athletes are at high risk of joint injuries. How may such

injuries be treated?

Following an initial medical examination of an injured joint, if no fractured bones are suspected,

conventional RICE treatment (rest, ice, compression and elevation) may be used together with

anti-inflammatory painkillers. RICE treatments reduce heat and oedema. Further investigations of

the damage may use X-ray examinations which would reveal whether bone fractures are present,

and MRI (magnetic resonance imaging) scanning would indicate whether any ligaments were

torn. MRI scans will also show whether there is a meniscus tear.

11


In the event of damage to a meniscus, a procedure called an arthroscopic menisectomy

(keyhole surgery) may be performed. Following surgery, physiotherapy is used to restore the

motion of the joint.

17. What are the advantages of using keyhole surgery rather than conventional surgery?

Anaesthetics carry an element of risk, but keyhole surgery is faster than conventional surgery since

very small incisions are made, so less anaesthetic is used and there is less associated risk to the

athlete.

With small incisions, less blood is lost, there is a reduced risk of infection, there is less damage to

tissues and less pain. As a result less pain medication is needed compared to conventional

processes. In addition, recovery time is shorter and there is also, the financial incentive of reduced

costs to the health services.

18. Describe the uses of X-rays, Computed Tomography (CT) scans, magnetic resonance imaging

and Functional Magnetic Resonance Imaging (FMRI) in the diagnosis of sports injuries

Correct diagnosis is important since appropriate management can reduce symptoms. With good

management, exacerbations are reduced and the health status of the athlete is improved.

The main reason for obtaining a radiograph when evaluating a patient for is to exclude alternative

options. X-rays are excellent for investigating images of hard tissues, such as bone, but they are

less effectively for producing images of soft tissues. X-rays are mutagenic, so they should only be

used when absolutely necessary.

CT scans combine X-ray images taken from many thousands of tiny X-rays coming from different

directions. This creates a cross-sectional view, so CT scans give a more complete picture of the

tissues imaged, than X-rays do. However, CT scans do not give fine structural details and images

are frozen in time. The X-rays used are mutagenic.

Magnetic resonance imaging (MRI) is produced using magnetic fields and radio waves. MRI

images show finer detail than CT scans and the use of magnetic fields and radio waves removes

the drawback of radiation which occurs when using X-rays and CT scans. With MRI, different tissues

respond differently to the magnetic field and radio waves, so distinct regions of injury can be

recognized in the images obtained. MRI technologies produce very detailed images so areas of

damage show clearly on the scans.

The advantages of fMRI are that it is possible to watch the functionality of the injured area and

the scans obtained by this technology give a spatially accurate image. The disadvantages are

that the process is noisy and stressful. The person must be immobile for the duration of the process

and any movement will reducing the accuracy of the image.

12


19. What do you understand by the term haematocrit and what group of athletes benefit from a high

haematocrit? (Paragraph 19)

The hematocrit measures how much space in a blood sample is occupied by red blood cells. An

increase in the number or size of red blood cells increases the space these cells occupy in the

blood, resulting in a higher hematocrit.

During exercise, the cardiovascular system has to deliver increased supplies of oxygen to working

muscles. It must also transport metabolic carbon dioxide to the lungs for excretion. The

haemoglobin in red blood cells acts as a buffer, and ATP release from red blood cells contributes

to vasodilation which occurs during exercise, and to improved blood flow to working muscles.

These functions require sufficient amounts of red blood cells in the circulation. Trained athletes

participating in endurance sports show a reduced hematocrit level which is the result of

mechanical rupture of red blood cells as they pass through the capillaries present in contracting

muscles. Therefore endurance athletes benefit significantly from elevated hematocrits.

20. How can a high haematocrit be achieved legally? (Paragraph 20)

By training at high altitudes where the PO2 is low. There are many physiological benefits to be

gained by training at high altitudes including;

- An increase in the number of cristae in the mitochondria and an increase in the numbers of

mitochondria in the muscles making aerobic respiration more efficient.

- An increase in the capillary density in the muscles.

- An increased number of the carbonic anhydrase enzymes present in the red blood cells that

facilitate the release of oxygen from red blood cells.

- An increase in the number of red blood cells which carry oxygen. Training at high altitudes

stimulates the production of endogenous erythropoietin. The higher the hematocrit value, the

more oxygen can be delivered to the muscles, per unit volume of blood.

- An increase in the blood flow to the lungs increasing the efficiency of gas exchange.

21. What is blood doping? Distinguish between autologous, homologous, and heterologous blood

doping. (Paragraph 19)

Blood doping is the injection of oxygenated blood into an athlete before an event in an illegal

attempt to enhance performance.

Autologous blood transfusions involve the collection and reinfusion of the athletes own blood.

Homologous (allogenic) transfusions involves the athlete collecting and infusing the blood of a

compatible donor into himself or herself.

Heterologous transfusions involve the athlete infusing blood from a different species.

13


22. What risks are associated with blood doping? (Paragraph 19)

Blood doping thickens the blood and the ensuing increased viscosity of the blood can slow down

heart rate and encourage blood clotting. This may lead to risks from heart disease, strokes and

cerebral and pulmonary embolisms. In homologous blood doping, the donors blood may contain

a virus which is then passed on to the athlete during the transfusion. Athletes using their own blood,

present themselves with significant health risks if the procedure is not carried out correctly, and if

the blood is not handled and stored properly.

23. Are elite athletes born or made? (Paragraphs 40-43)

Athletic ability is the result of complex genetic traits which are influenced by the environment. The

phenotype of the athlete is the result of interactions between genes and the training routines

practiced by the athlete. Advantageous genes, training, hard work and motivation all contribute

to the winning of medals. Training (the environment) develops, tones and strengthens muscles,

but genetic traits such as the proportion of slow twitch to fast twitch muscle fibres an athlete has,

is also significant in establishing phenotype. Certainly athletic phenotypes are the result of

continuous genetic variation and the polygenes which produce this type of variation. The genetic

input on performance enhancement is illustrated by considering the sprint gene. This gene

(ACTN3 or a-actin3) affects one of the proteins which make up the fast twitch fibres in muscles.

This gene causes fast twitch fibres to contract faster with greater power. Athletes with ACTN3 have

the explosive power essential to sprinters.

24. What are diuretics and why do athletes use them? (Paragraph 15)

Diuretics are substances that promote diuresis, the production of urine. Diuretics increase the

excretion of water from the body.

Athletes use diuretics in order to conceal their use of prohibited substances during the testing

process. A more dilute urine can hide the presence of illicit substances. For this reason diuretics

are banned both in and out of competition. They may be used in sports with weight categories

such as judo. The competitor dehydrates for the weigh-in and then rehydrates for the competition.

Diuretics are masking agents which hide the presence of a banned substance in the athletes

urine allowing the athlete to cover up their use and to gain an unfair competitive edge. Diuretics

are prohibited both in and out of competition. Note, both ethanol and water have diuretic actions

in the body.

14


25. How do diuretics exert their effects in the body and what side effects may develop from the use

of such substances by athletes? (Paragraph 15)

How diuretics exert their effects in the body is summarized below.

TYPE OF DIURETIC EXAMPLES MECHANISM OF ACTION

Aquaretics Juniper Increases blood flow to the

kidneys

Osmotic diuretics Glucose, especially in

uncontrolled diabetes

Promotes osmotic diuresis

Potassium-sparing

diuretics

Amiloride Inhibits the action of aldosterone

Xanthines Caffeine, theophylline,

theobromine

Inhibits the reabsorption of sodium

ions

There are several classes of diuretics and the side effects depend largely on the classes into which

each diuretic falls;

Overall, diuretics reduce blood volume and create electrolyte inbalance, specifically in the

reduction of blood potassium and sodium ions causing lassitude, muscle cramps and hypotension.

Muscle weakness, depression and confusion are also side effects caused by dehydration and the

loss of essential electrolytes in the urine.

26. How does the International Olympic Committee (IOC) promote fairness in top level sporting

events?

The IOC promotes top level sport in accordance with the Olympic Charter. The use of drugs to

enhance performance is considered as cheating and these drugs have adverse effects on the

health of athletes.

27. When athletes suffer injuries they may use Non-Steroidal Anti-Inflammatory Drugs (NSAIDS). Why

do athletes use these drugs and what are the risks involved in their use? (Paragraph 12)

Athletes may seek to prolong participation and to gain competitive advantages when competing

in events. To do this they may resort to taking chemically synthesized compounds. WADA does not

prohibit the use of NSAIDs since these compounds are not performance enhancing and their

analgesic and anti-inflammatory properties only give performance enabling. Consequently,

athletes use NSAIDs to relieve pain incurred by injury enabling them to train harder, longer. These

analgesics may reduce the athletes anxiety by building confidence. NSAIDs have unrestricted

availability as over-the-counter drugs. This enables athletes to self-administer these medications

prior to events to prevent pain and inflammation prophylactically.

Use of NSAIDs may give athletes a false sense of security, and by continuing to train further

damage may be incurred since the NSAIDS may mask the pain sufficiently to allow the athlete to

15


train to his/her limits of endurance. NSAIDS can cause a variety of side effects in susceptible

athletes e.g.; vomiting, nausea, headaches, bleeding and gastric ulcers.

28. What are opiate analgesics, what effects do they have in the body, and what are the problems

associated with the use of these drugs? (Paragraph 13)

These drugs are painkillers that act on the central nervous system.

These drugs reduce the intensity of pain signals reaching the brain and affect those areas of the

brain which can diminish sensations of pain. The hypothalamus of the brain has receptors with

which morphine can bind. The hypothalamus controls basic emotions including emotions involved

in the reduction of pain. In addition morphine can cause changes in the expression of

mitochondrial genes and in this way morphine influences cellular respiration. Examples of these

drugs include diamorphine (heroin), morphine and codeine.

Narcotic analgesics reduce the pain caused by injury. This helps athletes to train harder and

longer. However the action of the drug masks the pain and athletes may then over extend their

training and exacerbate their injury problems. Morphine is often used before and after surgical

procedures to alleviate severe pain. Codeine is usually used for mild pain. With the exception of

codeine these substances are prohibited during competitions.

29. Cannabinoids are the most widely used illicit drug in the western world. How do these drugs exert

their effects in the body? (Paragraph 4)

Cannabinoids are psychoactive substances derived from cannabis plants, examples include

hashish and marijuana. These drugs cause a feeling of relaxation.

Cannabinoid receptors have been located in the amygdala of mice models. Nerve cells in this

part of the brain synthesize and release their own natural endocannabinoids. This system

regulates anxiety and the response to stress by inhibiting signals which involve the neurotransmitter,

glutamate. Chronic stress can reduce the production of endocannabinoids and the

responsiveness of the receptors, leading to an increase in anxiety. Exogenous cannabinoids

reduce anxiety. Chronic use of these drugs compromises the efficiency of the receptors which

then increases anxiety! This can initiate a vicious cycle of increasing use which may lead to

addiction and a decreased motivation to perform and give maximum effort.

30. Why do athletes use these cannabinoid drugs and why are they banned?

Athletes use these psychoactive drugs to reduce their recovery time after exercise, to increase

their heart rate, to reduce their inhibitions and to release tension and anxiety. The effects of

marijuana on athletic performance are increased reaction time, decreased fine motor

coordination, vasodilation and an increased heart rate. These effects can cause an athlete to

reach maximum heart rate at a lower intensity of exercise which decreases maximum work

16


capacity. However it is important to distinguish between the use of these drugs for recreational

purposes and the intent to enhance performance.

Marijuana is not considered to be a performance enhancing drug, but it is on the banned list.

31. What are stimulants? Why do athletes use stimulants and why are these substances banned during

competition. (Paragraph 16)

Stimulants are a group of substances which boost alertness, attention, physical activity and energy

levels as well as elevating blood pressure. These substances have great potential for abuse and

addiction and with the exception of caffeine, these drugs are banned during competitions.

Stimulants act on the central nervous system by increasing breathing rates and brain functions

and in this way they stimulate the body both mentally and physically.

Stimulants are classified into two categories: non-specified and specified. The non-specified group

includes the more powerful stimulants and if athletes test positive for this group of stimulants then

severe sanctions are imposed. In contrast specified stimulants are less potent and athletes testing

positive for this group of stimulants receive less severe sanctions.

Amphetamine and cocaine are examples of non-specified stimulants, while adrenaline and

strychnine are examples of specified stimulants.

Athletes use stimulants since these drugs increase the ability of the athlete to exercise at the

optimum level, combat tiredness, and to suppress appetite.

32. Amphetamine is a potent central nervous system stimulant. Why do athletes abuse amphetamine

and what are the risks involved in the use of such drugs? (Paragraph 17)

Amphetamines increase excitatory neurotransmitter action in the brain. In particular, they

influence nor-adrenaline and dopamine neurons by impacting reuptake inhibition in dopamine

neurons of the brain. Such drugs are prohibited during competition.

Phenylephrine and pseudoephedrine are ingredients of many cold and flu decongestant

medications which may take relatively long time periods to clear the body especially when they

are used in combinations with other medications. Ephedrine is prohibited above certain threshold

values in the urine. It is advisable that athletes wishing to avoid inadvertent positive tests should

use a non-prohibited alternative such as ipratopium which is an anticholinergic agent used to

treat asthma. This drug is used as a performance and cognitive enhancer. It is also used

recreationally for the euphoria action.

Performance is enhanced since amphetamines decrease reaction times, increase resistance to

fatigue and improve muscle strength. Amphetamines cause better cognitive control, increased

alertness and emotional euphoria.

17


There are many risks associated with amphetamine use. The substance is addictive and in high

doses it can cause delusions and paranoia. Substituted amphetamines include

methamphetamine and ecstasy. These substances also give euphoria and an increase in muscle

strength.

33. Give a brief account of synaptic transmission in cholinergic neurons.

When an impulse arrives at a pre-synaptic (cholinergic) knob, Ca2+ ion channels which are

present in the pre-synaptic membrane, open. The Ca2+ ions then migrate by diffusion into the

synaptic knob, where they act as a signal promoting the migration of transmitter vesicles towards

the pre-synaptic membrane. The vesicles fuse with the pre-synaptic membrane and the

transmitter molecules of acetylcholine are released by exocytosis into the synapse.

The transmitter molecules diffuse rapidly across the very narrow synaptic cleft and are recognized

by complementary protein receptors on the post-synaptic membrane. Following recognition, Na+

ion protein channels in the post-synaptic membrane open, and Na+ ions rapidly diffuse down an

electrochemical gradient into the post-synaptic neurone, causing depolarization in the post-

synaptic cell. When the Na+ ion concentration in the post synaptic cell exceeds a threshold value

then an impulse is generated in the post-synaptic neurone.

Following the generation of the impulse in the post-synaptic cell, transmitter molecules in the

synapse are catalytically hydrolysed by acetylcholinesterase enzyme molecules positioned on the

post synaptic membrane. The ethanoic acid and choline products of this hydrolysis are

reabsorbed by diffusion into the pre-synaptic cell where they are resynthesised into acetylcholine

using energy from hydrolysis of ATP molecules produced in the mitochondria of the synaptic knob.

34. Why does having a high proportion of fast twitch muscle fibres suit sprinters?

Sprinters need fast, powerful muscle contractions. They also need to be able to develop maximum

force very quickly. Fast twitch muscle fibres have characteristics which facilitate such contractions

making these fibres suitable to power athletes.

Fast twitch muscle fibres have a sarcoplasm rich in the enzymes which catalyse anaerobic

respiration. Under anaerobic conditions these fibres generate ATP rapidly from stores of a high

energy molecule called creatine phosphate, using lactate fermentation. When creatine

phosphate breaks down it acts as a phosphate donor in the synthesis of ATP. Creatine phosphate

is resyntheised during aerobic respiration. Glycogen is the fuel for lactate fermentation. Fast twitch

fibres carry relatively low levels of myoglobin and have relatively few mitochondria in their

sarcoplasm. Fatigue in power athletes is due to the build- up of lactate and hydrogen ions.

18


35. Construct a table to compare slow and fast twitch muscle fibres.

Comparison of slow twitch and fast twitch fibres

- Slow twitch fibres are red fibres because they contain a high proportion of

myoglobin.

- Good blood supply. - Large numbers of mitochondria which

generate large amounts of ATP.

- Respiration is aerobic avoiding accumulation of lactate in the muscles

which would cause fatigue.

- Use glycogen as a fuel together with fats from adipose tissue.

- The disadvantage of aerobic respiration is that the ATP cannot be generated very

fast.

- Slow twitch fibres are not very powerful. - Suited to endurance athletes.

- Fast twitch fibres are white because they contain relatively low levels of myoglobin.

- Small numbers of mitochondria. - The sarcoplasm is rich in the enzymes which

catalyse anaerobic respiration.

- They generate ATP quickly from stores of creatine phosphate and lactate

fermentation by anaerobic respiration.

- When creatine phosphate breaks down it releases phosphate ions which can be used

in the synthesis of ATP.

- Creatine phosphate is regenerated during aerobic respiration.

- During lactate fermentation they can only use glycogen as a fuel.

- Lactate ions and hydrogen ions build up during lactate fermentation causing fatigue.

- Suited to power athletes.

36. Why does having a high proportion of slow twitch muscle fibres enhance performance in

endurance athletes?

Slow twitch fibres carry a high proportion of myoglobin so oxygen storage in muscles is maximized.

Such fibres have an excellent blood circulation and the sarcoplasm carries large numbers of

mitochondria which generate large amounts of ATP. Slow twitch fibres do not contract powerfully

and they are suited to prolonged exercise of the muscles needed by endurance athletes.

37. Construct a flow diagram which summarises blood clotting.

Damaged tissues release platelets which then release thromboplastin an enzyme which catalyses the conversion of prothrombin into thrombin. Calcium iona are necessary for

this stage .

Thrombin is an enzyme which catalyses the conversion of fibrinogen, a soluble plasma protein, into fibrin which is a fibrous protein which forms the foundation of the clot.

Fibrin forms a mesh of fibres which trap blood cells and platelets leaking from the wound. In this way a clot is formed. Clotting is a cascade process.

19


38. What do you understand by the term generic with respect to drugs? (Paragraph 21)

The generic name of a drug is the chemical name of the drug. It refers to the chemical makeup

of a drug rather than to the advertised brand-name under which the drug is marketed. The term

generic refers to any drug marketed under its chemical name without advertising. Generic drugs

without brand names are cheaper than the brand-name drugs even though they are chemically

identical to the brand name drugs and meet the Food and Drug Administration (FDA)

requirements for safety, purity and effectiveness.

39. What do you understand by the term anabolism and what are anabolic agents? (Paragraphs 22-

24)

The term anabolism encompasses all biochemical processes which involve the synthesis of larger

molecules from smaller molecules. Such processes are endergonic in nature.

Anabolic Androgenic Steroids (AAS), are synthetic testosterone preparations. These substances

fall into two categories;

i. Exogenous steroids which are those substances which cannot be produced naturally in the body

e.g. nadrolone.

ii. Endogenous steroids which are those substances that can be produced naturally in the body e.g.

dehydroepiandrosterone (DHEA) and testosterone.

40. Why do athletes abuse anabolic agents and why are these substances banned? (Paragraphs 21-

24)

Anabolic steroid use is carried out for a variety of reasons;

i. The athletes may wish to increase muscle size and strength and to reduce the time required to

recover after exercise. In addition the athletes may wish to train harder for longer periods of time.

ii. Peer pressure promotes the use of anabolic steroids when athletes fear that training alone may

not be sufficient to ensure success.

iii. Athletes may wish not only to improve performance, but also to improve their appearance and

muscle building by increasing protein synthesis.

iv. Although, testing procedures are now in place to deter steroid abuse, new designer drugs are

constantly becoming available to athletes, and currently these can escape detection.

Anabolic steroids are banned because they enhance performance giving the athlete an unfair

advantage. In addition these drugs carry serious threats to the health of the athlete e.g.

atherosclerosis and psychiatric disturbances

20


41. Female steroid hormones do have anabolic effects but in spite of this contraceptive pills are

permitted to female athletes. What advantages could these pills give to female athletes?

(Paragraph 23)

Oral contraceptives tend to reduce menstrual blood loss which would, in turn, reduce the

occurrence of iron-deficiency anaemia. In addition the use of these pills may make menstruation

easier to cope with and the athlete can control the timing of menstruation so that it does not

coincide with athletic events. Also the contraceptive protection is also recognized as beneficial

to female athletes.

42. How does testosterone act in target cells? (Paragraph 22)

Steroids are chemically dissimilar to lipids, but they behave very much like lipids. Steroid hormones

e.g. testosterone can pass across the phospholipid cell membranes of target cells. Once inside

the cytoplasm, testosterone binds with specific, complementary receptors, forming a

hormone/receptor complex which then migrates into the nuclei of target cells. The

hormone/receptor complex acts as a transcription factor by binding to the DNA and switching

on specific genes linked to protein synthesis. The RNA produced is modified so the type of proteins

produced is changed. Testosterone stimulates the protein synthesis that results in bigger and

stronger muscles. However natural endogenous testosterone is rapidly broken down in the body.

43. Describe the process of atherosclerosis. (Paragraph 21)

High blood pressure damages the endothelium of arteries causing blood platelets to stick to

damaged tissue under the endothelium. The platelets release chemicals which cause cells under

the endothelium to proliferate forming fatty deposits called plaque. Inflammation occurs during

which monocytes enter the area where they then engulf cholesterol. The plaque consists of lipids

and cholesterol delivered to the plaque by LDL's (low density lipoproteins). In addition the LDL's

stimulate the monocytes to become part of the developing plaque.

As cholesterol and lipids accumulate into an atheroma, fibrous tissue and calcium deposits

develop around the plaque and over time the artery walls become hard and less elastic and the

lumena of the arteries become narrower.

The accumulation of platelets around the plaque and the backing- up of blood in the areas

concerned, causes the blood clotting cascade to be initiated and the clots which form will also

block the lumena of the arteries.

The above process forms a positive feedback loop during which an increase in a factor (such as

blood pressure) can trigger a further increase in that factor. Blood flow behind the atheromatous

plaque may stagnate causing an aneurism to develop.

21


44. What are the characteristic features of hormones?

Hormones are extracellular, regulating, chemical substances which are produced by endocrine

glands which secrete their hormones into the blood. The hormones are distributed around the

body but they only produce their effects in cells which have receptors which are complementary

to the conformation of the hormone.

Hormones are a heterogeneous group of chemical substances which includes proteins such as

erythropoietin and insulin, steroids such as testosterone and oestrogen, and adrenaline which is

an amine.

Hormones are small molecules which are effective in very low concentrations since they induce

cascade events. Hormones generally have long-lasting and widespread effects in the body.

45. Paragraph 26 refers to a class of peptide hormones which were added to the IOC doping

categories which already existed. Why were these substances added to the list and give an

indication of the functions of these substances?

The IOC introduced this category of substances since all the included substances are anabolic.

Name of substance Functions

Human chorionic

gonadotrophin (hCG)and

analogues

Secreted in early pregnancy. Stimulates the corpus luteum to

continue secreting oestrogen and progesterone thus

maintaining the endometrium.

Corticotrophins including

the adrenocorticotrophic

hormone (ACTH)

Secreted by the anterior pituitary gland. It increases the

concentration of cholesterol and steroids in the adrenal cortex

and the output of steroid hormones such as cortisol.

The human growth

hormone (hGH), insulin-

like growth factors and

mechano-growth factors

Synthesised by the anterior pituitary. It stimulates growth, cell

division, especially in bones and skeletal muscles, maintains

bone and muscle mass in adults and promotes protein synthesis.

The insulin-like growth factors are produced in the liver following

stimulation by hGH, and they are similar in structure to insulin and

initiate intracellular signaling.

The mechano-growth factors stimulate repair of local muscle

damage caused by resistance exercise, by activating muscle

stem cells.

Erythropoietin and insulins Erythropoietin is a glycoprotein which controls red blood cell

production. It is produced in the kidney and is a signaling

molecule.

Insulin is a protein synthesized by the Islet of Langerhans beta-

cells in the pancreas. Insulin functions to lower blood glucose,

amino-acids and fatty acids when these are in excess.

22


46. Three important terms are used to refer to molecules which bind to hormone binding sites or

receptors. These terms are; agonists, antagonists and inhibitors. What do you understand by these

terms?

Agonists are molecules that bind to complementary hormone binding sites associated with

specific target cells. These molecules induce all the post-receptor events which will contribute to

the desired biological effect. These molecules in effect, mimic the endogenous hormone. Natural

hormones are agonists.

Antagonists are molecules that bind to complementary hormone binding sites associated with

specific target cells and in doing so they block the binding of the agonist, so intracellular responses

to agonists fail to occur.

Inhibitors may suppress hormone action in a variety of ways, for example the action of many

peptide hormones depends on the release and catalytic action of adenyl cyclase. This enzyme

catalyses the conversion of ATP into an intracellular messenger called cyclic AMP which in turn

triggers cellular events in the target cells. Somatostatin blocks the catalytic activity of adenyl

cyclase.

47. New illicit drugs are difficult to test for so there is an arms race between the use of new drugs by

athletes and the detection of these drugs by the athletic regulatory authorities. What is the use of

mass spectrometry in the detection of new, illicit drugs being used by athletes and why is this

detection essential?

WADA has banned a new illicit experimental drug called peroxisome-activated receptor-delta

agonists (GW1516). The reason for the ban is that this drug is perceived to artificially increase

exercise tolerance and capacity. Such performance enhancing drugs are being developed

continuously and it is of paramount importance to doping control authorities to protect the

integrity of elite sports. Consequentially, sports drug testing laboratories need to establish

detection methods allowing the identification of the substance in doping control specimens.

There has been considerable progress in testing for synthetic steroids, such as nandrolone, and in

testing blood for hGH, and now isoform assays have been developed for detecting recombinant

GH abuse.

In the case of GW1516, mass spectrometry gives sensitive, precise data concerning the amount

and type of substances in a sample. The spectra produced determine the isotopic signature of

the specimen.

There is a constant arms race taking place between individuals seeking to circumvent the rules

which apply to doping, and laboratories which are trying to develop techniques which will detect

the use of illicit performance enhancing drugs or methods. Vigorous, effective testing can be

announced or unannounced and the sanctions imposed are severe when competitors are

23


caught out. Although there are many who believe that the bans on drugs should be lifted so that

the playing field becomes level, this attitude ignores the very significant health risks which many

banned substances carry. Surely, the safety of the athlete is of paramount importance.

48. Describe an absolutist and a relativist ethical position on the proposal to set a maximum total red

blood cell count for all athletes rather than measuring erythropoietin levels.

Absolutists take the view that no drugs under any circumstances should be allowed in sport and

so the application of a maximum red blood cell count is not adequate as it allows for the use of

drugs. However relativists consider that the setting of a maximum level for red blood cell counts is

the only fair way to make sure that athletes are not tempted to increase their natural red blood

cell count to the point where they may be damaging their health by using erythropoietin.

49. What do you understand by the term homeostasis?

Homeostasis is the ability of an organism to maintain its internal environment, (blood and tissue

fluid). A constant internal environment provides optimum conditions in which enzyme systems can

operate. In order to achieve internal environmental stability, control mechanisms must exist in the

organisms. The efficiency of the control systems is measured by how little displacement there is

from a reference point and the speed with which the set point is restored.

Homeostatic processes must be free to fluctuate because it is the fluctuations which activate the

control systems.

50. Paragraph 30 refers to the terms hyperglycaemic and hypoglycaemic, what do these terms mean

and how does the human growth hormone promote hyperglycaemia?

Hyperglycaemia occurs when blood glucose levels rise outside the normal limits which are

controlled by normal negative feedback processes.

Hypoglycaemia occurs when blood glucose levels drop below the normal fluctuation range for

blood glucose levels.

The human growth hormone raises blood glucose levels by increasing protein synthesis and

promoting the breakdown of fatty acids in adipose tissue. Stress, exercise and high protein diets

increase the secretion of the growth hormone. Thus, the growth hormone stimulates

gluconeogenesis (the production of glucose from non-carbohydrate sources) in the liver resulting

in a net increase in hepatic glucose output.

24


51. Insulin can cause severe hypoglycaemia if not administered correctly and for this reason insulin

is now only available as a prescription only drug. How does insulin lower blood glucose levels?

Beta-cells in the Islets of Langerhans of the pancreas, monitor blood glucose levels. Blood glucose

levels are controlled using negative feedback processes.

When blood glucose levels are elevated insulin is secreted from the beta-cells of the Islets and is

transported in the blood to target cells in the liver, adipose tissues and skeletal muscles promoting

glycogenesis (the conversion of glucose into glycogen). The glycogen is then stored in these

organs. The reduction in blood glucose involves GLUT 4 transporter systems which shunts the

glucose molecules from the blood and into the target cells by facilitated diffusion.

52. Most biological systems use negative feedback mechanisms. Distinguish between negative and

positive feedback systems.

In negative feedback the information fed back into a system then turns the system off. Positive

feedback occurs when a deviation from a set point results in changes which cause an even

greater deviation from the norm.

53. What is a gene?

A gene is a specific segment of DNA on a particular chromosome, which carries a unique number,

type, and sequence of codons (triplets of the nitrogenous bases adenine, thymine, guanine and

cytosine) which are transcribed into a complementary number, type and sequence of

ribonucleotide codons on MRNA. This mRNA is translated into a specific number, type and

sequence of amino-acids linked by peptide bonds. The gene therefore carries a code for a

particular protein.

54. Distinguish gene therapy from gene doping.

As a result of the Human Genome Project considerable progress has been made concerning

mapping of the human genome and gene therapy is now applied in the management of human

diseases e.g. cystic fibrosis. Gene therapy seeks to replace defective genes in vivo, or it seeks to

promote long-term endogenous synthesis of deficient proteins. Unfortunately, such methods are

increasingly being applied by athletes. Often the use of these substances can increase muscle

mass and strength. When applied in this way gene doping carries significant health risks.

Simultaneously medical laboratories are laboring to develop new techniques which can detect

gene doping.

WADA describes gene doping as the non-therapeutic use of cells and genes or the modulation

of gene expression in order to enhance athletic performance. It is likely, in the near future that

gene doping will be an increasing reality which will cause some members of the public to support

genetic enhancement, since they consider the distinction between gene therapy and genetic

25


enhancement to be obscure. In addition, legislation will be slow to implement and difficult to

enforce. It may also be considered that such enhancements are within the spirit of sport, other

people will simply consider gene doping as a sophisticated form of cheating. Due to the

advances in gene therapy, methods of delivering genes are already being investigated, e.g.

vectors such as harmless viruses and liposomes are already in use. The potential for doping would

then be to introduce normal genes into the body thus enhancing the effects of normal cells.

55. How does protein synthesis take place in cells?

Protein synthesis takes place in two phases. The first phase is transcription in which the specific

number, type and sequence of codons on DNA determines the complementary number, type

and sequence of codons on messenger RNA (mRNA).

Transcription occurs in the nucleus of the cell and mRNA is a transcript of only one gene (cistron).

Only one chain in the DNA double helix is the coding template for transcription. At the beginning

of transcription the enzyme helicase catalyzes breaking of the hydrogen bonds which hold the

double helix together. Another enzyme called mRNA polymerase attaches to the promoter site at

the beginning of the gene starting transcription. During transcription mRNA polymerase moves

along the cistron in the 5 to 3 direction catalyzing the condensation of free ribonucleotides into

a complementary strand of mRNA. Construction of the mRNA depends on complementary base

pairing; adenine on DNA with uracil on mRNA, thymine on DNA with adenine on mRNA, guanine

to cytosine, and cytosine to guanine. On reaching a stop codon on DNA (the terminator) the

mRNA polymerase detaches from the DNA template and the mRNA molecule peels away from

the DNA template.

The second phase of protein synthesis is called translation during which the code on the mRNA is

translated into a specific polypeptide.

The number, type and sequence of codons on mRNA determines the corresponding number, type

and sequence of amino-acids in the primary organization of a protein.

Translation takes place in the cytoplasm of the cell. The mRNA complexes with a ribosome which

positions the mRNA so that the genetic code can be read.

There are 20 types of amino-acids in living systems and 20 types of tRNA to carry them. Each type

of tRNA has a specific anti-codon which is complementary to a specific codon on the mRNA.

Codon/anti-codon recognition between mRNA and the tRNAs ensures that amino-acids take up

the correct primary positions needed to synthesize the specific polypeptide.

During translation the ribosome moves along the mRNA, beginning at a start codon, and the

codons on the mRNA are recognized by complementary anticodons on the tRNA. At each

position occupied by the ribosome two tRNAs each carrying a specific amino-acid are

complexed together. The enzyme peptidyl transferase catalyzes the formation of a peptide bond

26


between the amino-acids. In this way one amino-acid at a time is added to the polypeptide chain.

Translation begins at a start codon and continues until the ribosome reaches a stop codon on the

mRNA. The ribosome may return to repeat the translation process along the same mRNA, making

translation a cascade process.

56. How does erythropoietin express itself in target cells?

Erythropoietin is a peptide hormone secreted by cells in the kidney. It is transported to target cells

in the blood. This hormone is an extracellular messenger which is recognized by complementary

protein receptors in the target cell membranes. Following recognition, the enzyme adenyl cyclase

migrates from the cell membrane into the cytoplasm of the target cells where it catalyses the

conversion of ATP into an intracellular messenger called cyclic AMP (cyclic adenosine

monophosphate). Eventually, a protein kinase cascade is triggered. The cascade involves a

number of enzymes which finally produce a product which enters the nucleus of the cell where it

acts as a transcription factor binding to DNA and switching on the genes involved in protein

synthesis. Post-transcriptional changes to mRNA can produce variations in the enzymes involved

in the cascade which switch on genes needed for the production of more red blood cells.

57. Suggest how it is possible for a single gene to have more than one variant.

Not all the mRNA transcribed from a specific gene is used to synthesize proteins. The parts of the

genes which are used to synthesize proteins are called exons, and the parts which do not code

for proteins are called introns. Transcription takes place along the whole length of the gene, so

the first mRNA produced contains a complementary sequence of both introns and exons. This

mRNA is called pre-mRNA. A number of processes take place before the mRNA complexes with

a ribosome, including enzymatic removal of introns in a process called splicing. Sometimes, some

exons are also removed, so the code on the final mRNA is different to the code on the original

DNA. Such post-transcriptional changes to mRNA from a single gene, gives rise to gene

polymorphism i.e. to variants of the gene.

58. Briefly discuss the process for presenting research results to the scientific community.

Scientists propose hypotheses to explain phenomena, and they then design experiments to

investigate these hypotheses. The steps taken in experimental procedures must be repeatable, so

that peer sharing and peer repetitions can take place. This improves the validity of the processes

involved. In addition, the methodology used must be archived. The work must include statistical

assessments which verify the validity of the work Manuscripts of the work performed are forwarded

to the editors of prestigious journals, such as Nature and Science. Peer review and evaluation of

the submitted material may result in publication of the work which then becomes available to the

scientific community for examination and study. Scientific meetings are then organized for the

work to be debated. Funding for scientific research should always be unbiased.

27


59. What is inflammation?

Inflammation is a protective, stereotyped, kind of innate immunity. The cells and their products

which mediate this response must be localized at the site of the infection. Inflammation is a non-

specific way in which the body responds to infection.

60. Describe the process of inflammation (Paragraph 3)

The inflammatory response is a cascade which is initiated by macrophages, (a type of leukocyte).

These cells have cell surface receptors, capable of recognizing pathogen antigens. When these

cells are activated they release inflammatory mediator molecules, such as histamines, which

induce vasodilation. This response results in increased localized blood flow and the surrounding

area shows redness, pain and local heat. The locally raised temperature reduces the efficiency of

pathogen reproduction. The histamines also increase the permeability of local blood vessels. As a

result, plasma fluid from the blood, white blood cells, especially neutrophils, and plasma proteins

including antibodies, leak out of the vessels. The localized increase in tissue fluid causes swelling

(oedema).

61. What do you understand by the term gene mutation? (Paragraphs 40-42)

The structure of DNA is very stable. This is due to the very specific way in which the nucleotide

bases bond together as complementary base pairs. The stability of the DNA molecule, the

accuracy with which is replicated, and the way the information encoded within it is used, are the

basis of modern genetics. However DNA replication is not perfect. The capacity for change in

hereditable variation is due to mutations.

A gene mutation is a sudden, random change in the genetic material within a gene, producing

new alleles. These mutations may not only be spontaneous, they may also be induced.

There are three main ways in which the base composition of the DNA in a gene may be altered

by a mutations. These are by addition of bases into the base sequence, deletion of bases and

substitution of bases.

Gene mutations can be classified into several categories.

In a same sense mutation a base substitution does not alter the amino-acid sequence of a

polypeptide.

Missense mutations involve base pair substitutions which result in one amino-acid being

exchanged for another amino-acid, in a specific position

Frameshift mutations involve additions or deletions of bases, in a way that causes the gene to be

misread.

28


Nonsense mutations are addition, deletion or substitutions of bases that changes a codon

specifying amino-acid into a stop codon, which terminates the polypeptide chain.

62. Many athletes who have tested positive for a banned substance, claim that they had only used

dietary supplements. Discuss. (Paragraphs 32-34)

Some athletes appear genuinely surprised when they test positive for a banned substance and

deny using banned substances However, they may admit to using dietary supplements to support

their exercise demands.

Doctors and professional exercise physiologists involved in setting the standards to which samples

from athletes are compared, know that they cannot use the standards applied to non-athletes,

but rather they must set their standards as the norm for the group of athletes being studied.

However the reference ranges developed may not cover the entire group being tested, and this

creates an ethical grey area in which a small number of athletes tested may be outside the limits

of the given range.

The use of dietary supplements by athletes is widespread. Inherent in this usage are a number of

problems for athletes resulting from deliberate or accidental contamination of supplements.

Legislation does not impose the rigorous testing used for therapeutic medications in the control of

dietary supplements. Contaminants identified in supplements include testosterone, nadrolone,

pro- hormones and caffeine. In these cases it is likely that products have been deliberately

adulterated.

In competitive sports there is a strict liability which places responsibility on the athletes concerning

ingestion of supplements so athletes testing positive for anabolic steroids originating from

contaminated supplements are still liable to sanctions, although there are probably instances of

inadvertent ingestion of banned products present in innocuous supplements.

63. Why are sports inherently unfair? (Paragraphs 50-52)

WADA aims to protect the athletes right to participate in doping-free sport, thus promoting health,

fairness and equality in competitive sports. This notion is obsolete since it is now appreciated that

advantageous genes give athletes a massive advantage e.g. Eero Mantyranta has a mutation in

the EPOR gene which gives him a naturally very high hematocrit level compared to other athletes.

Another example of the significance of possessing advantageous genes is Usain Bolt who has a

sprint gene (ACTN3) which affects one of the proteins which make up fast twitch fibres in muscles.

This gene is not needed for muscles to work but it does help the muscles to contract faster and

more powerfully. Add this to environmental factors such as training, hard work and motivation

then success can be predicted. In the future some kind of handicapping system based on

inherited advantages or disadvantages may level the fairness playing field but until then some

athletes without such genetic advantages consider that the only way they can surpass genetically

29


primed athletes is to indulge in doping. For example, in order to surpass Mantyrantas superiority,

athletes could enhance performance using exogenous EPO, blood doping, sleep in an oxygen

tent, train at high altitudes or use doctors who are willing to help the athletes beat the system of

abuse detection.

Another factor which contributes considerably to the fairness of sports competitions is the non-

equality of the resources available to athletes. This is where funding becomes a critical factor in

the athletes arsenal.

The rules imposed by WADA and the IOC do not cover the protection needed to ensure the

athletes safety. E.g. the lack of a safety limit on the concentration of red blood cells, which above

certain levels can significantly increase the risks of heart attacks. Dehydration makes this risk even

worse

64. How are negative and positive feedback mechanisms involved in the maintenance of a relatively

constant internal temperature during exercise?

Metabolic reactions produce heat. During aerobic and anaerobic exercise in the muscles the

amount of heat produced increases significantly. High temperatures can denature enzymatic

proteins, causing them to lose their conformations thus impairing the metabolic processes they

are involved in. Maintenance of a fairly constant temperature by physiological processes involves

vasodilation, increased volumes of blood flowing through the surface capillaries and sweating. All

these negative feedback control processes promote heat loss. During exercise it is vital that the

core temperature does not rise above the high critical value when positive feedback mechanisms

respond by increasing metabolic rate causing a further increase in core temperature until lethal

levels are reached.

65. Therapeautic drugs go through rigorous testing and monitoring in comparison to dietary

supplements. Briefly describe the phases through which the therapeautic drugs must pass before

they can be marketed? (Paragraph 50)

The pre-clinical stage involves investigations into the effects of the drug on cells, tissues and organs.

Later investigations may then analyse the effects of the drug on invertebrate animals such as

worms, and then mammalian models are used. Mammalian ce

Edexcel biology JUNE 2015 scientific article questions

Documents

Transcript of Edexcel biology JUNE 2015 scientific article questions