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Practice questions > Exampro - infection and reponse > Flashcards

Exampro - infection and reponse Flashcards

1
Q

(b) Suggest one reason why low doses of the drug are used in Phase 1 clinical trials.

A

To reduce risk
To look for side effects

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2
Q

(c) Suggest two reasons why healthy volunteers are used in Phase 1 clinical trials.

A

too great a risk for ill person / patient

patient might be taking another drug

side effects of drug are easier to identify

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3
Q

The results of clinical trials can only be published after peer review by other scientists.

Suggest one reason why the results must be reviewed by other scientists

A

*   to prevent false claims

*   to make sure the results / conclusions are correct / valid

ignore references to accuracy, reliability or precision

*   to avoid bias

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4
Q

(a)  Suggest one reason why the actual number of cases of measles in England and Wales might be higher than is shown in the table above

A

ot everyone would go to the doctor
*   sample will not always be sent for analysis

*   some cases not tested / diagnosed / confirmed

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5
Q

Vaccinating a large proportion of the population reduces the spread of the measles virus.

Explain why.

A

(c)  most people are immune so do not become ill (from infection)

less chance of non-immune / unvaccinated individuals being exposed to pathogen / measles / virus

less spread of disease

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6
Q

Explain the differences between antibody production after the vaccine injection and after exposure to the measles virus.

A
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7
Q

(b) Suggest why the data is given per 100 000 of the population and not as the number of people.

A

(b) to control for the different (group) population sizes

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8
Q

The scientists recommended that the antibiotic should be used at a concentration of 5 mg/dm3

Suggest two reasons why the scientists recommended this concentration.

A

higher concentrations did not show much improvement

less likely to cause toxic / side effects than at higher concentrations

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9
Q

The first stage is pre-clinical tests using live cells, tissues and animals.

Describe the other stages of drug testing.

A

phase 1 clinical testing:

*   tested on healthy volunteers

*   low doses used

reason:

*   to test for side effects / toxicity / safety

phase 2 clinical testing:

*   tested on patients

*   patients given placebo or drug

*   double blind trial

reason:

*   to test for side effects / toxicity / safety

*   to test its efficacy / effectiveness

phase 3 clinical testing:

*   larger numbers of patients used

*   patients given placebo or drug

*   double blind trial

reason:

*   to verify efficacy / effectiveness

*   to determine correct dose

prior to licensing:

*   analysis of results

*   peer review

reason:

*   to check results are valid

*   to avoid bias

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10
Q

Dose

A

Dose

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11
Q

Efficacy

A

Whether teh drug treats the illness

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12
Q

Toxicity

A

Side effects making the person ill

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13
Q

Evaluate the use of unlicensed drugs and vaccines during the EVD outbreak.

Give a conclusion.

A

pros

  • might save some lives
  • vaccine could reduce chance of future outbreaks
  • patient made aware of risk and agreed to use of drug
  • sharing of results could speed up development of effective vaccines / drugs
  • used mainly for health workers who were risking their lives to help

cons

  • could be dangerous

or

vaccine could harm a healthy person

  • goes against legislation / laws governing drug development
  • might set a precedent for other drugs not to be fully tested
  • unfair as not available to the African people
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14
Q

Pathogens make us feel ill.

Give one reason why.

A

(produce) toxins / poisons

  • (cause) damage to cells
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15
Q

Give two other ways that white blood cells protect us against pathogens.

A

produce antitoxins

1

engulf / ingest / digest pathogens / viruses / bacteria / microorganisms

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16
Q

Describe other differences in antibody production after infection compared with after vaccination.

A

(after infection)

accept converse if clearly referring to before vaccination

1

rise begins sooner / less lag time

steeper / faster rise (in number)

1

longer lasting or doesn’t drop so quickly

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17
Q

Vaccination against the measles virus will not protect the child against the rubella virus.

Why?

A

antibodies are specific

18
Q

(c) What is the advantage of vaccinating a large proportion of the population against measles?

A

(c) reduces SPREAD of infection / less likely to get an epidemic

19
Q

(a) (i) Explain fully why antibiotics cannot be used to cure viral diseases.

A

viruses live inside cells

1

viruses inaccessible to antibiotic

20
Q

There has been a large increase in the populations of many antibiotic-resistant strains of bacteria in recent years.

Explain why.

A

non-resistant strains killed (by antibiotics)

  • so less competition
  • overuse of antibiotics / antibiotics prescribed for mild infections
21
Q

(d) In immunisation against polio a second dose of the weakened virus is given (this is known as a booster). Suggest why this booster is necessary.

A

(d) so more antibodies made;

22
Q

Using the diagram to help you, suggest why the body’s defence against disease X would not be effective against disease Y.

A

(a) shape of antibody is not complementary;

accept shapes of antibody and antigen do not match or antibody does not correspond to antigen Y or is not the same shape as antigen Y or antibody different shape

1

so unable to attach or join to antigen Y

23
Q

(i) Suggest the possible cause of the reaction when a person who is already immune is tested, as shown in diagram A.

A

antibodies in blood or in skin or in body;

accept already have the antibodies

1

     react with (injected) antigens or bacteria;
24
Q

(ii) Explain why the injection of tuberculosis bacteria (diagram B) causes immunity but does not cause the disease.

A

bacteria weak so do not cause disease

accept not harmful

do not accept bacteria are dead

cause antibody production;

memory cells remain;

accept a suitable description

so body can quickly produce more antibodies in a real infection;

25
Q

The influenza virus damages the cells lining the respiratory tract causing sore throats.

      Coughing and sneezing spread the virus.

(a) Give the correct term for this method of spreading an infection.

A

(a) droplet infection or aerosol infection

26
Q

(b) In an immunisation programme such as that for MMR (Measles, Mumps and Rubella), suggest why it is essential for a large proportion of the child population to be vaccinated in order to protect the few individuals who are unable to be vaccinated.

A

(b) so there is no large group which could catch the infection/pass on the infection

27
Q

(a) Explain, as fully as you can, how the body’s white blood cells respond to infections.

A

engulf bacteria
produce antibodies
produce antitoxins
effect of antibodies/antitoxins

28
Q

(c) Explain why the BCG vaccine is not effective as a cure for people who already have tuberculosis.

A

adds more bacteria (mild)
does not affect TB bacteria

29
Q

(iii) After being ingested, the microbes are digested in the cells. Briefly explain what happens to the proteins that the microbes contain.

A

(iii) broken down, by enzymes into amino acids

30
Q

(b) Explain how bacteria cause disease once they get into the body.

A

v(b) reproduce rapidly produce toxins

31
Q

Explain, as fully as you can, how immunisation works.

A

mild or deal microbes introduced white cells produce antibodies
which can destroy disease microbes
idea of memory cells
idea that injecting antibodies give immediate production

32
Q

why is a plcebo good

A

as a control group

  • for comparison
  • to see if the drugs worked
  • to take account of psychological effect
33
Q

(i) Giving ibuprofen might be better than giving paracetamol because ________

A

ibuprofen reduces body temperature faster

  • ibuprofen reduces temperature more
  • ibuprofen doesn’t need to be taken as often
  • ibuprofen keeps body temperature lower / normal / 37 °C for longer
34
Q

Giving only ibuprofen might be better than giving a combination of paracetamol

and ibuprofen because __

A
  • body temperature decreases at a similar rate
  • ibuprofen maintained body temperature close to normal / 37 °C

(better to) take fewer drugs

allow less chance of overdose

  • easier to administer
35
Q

MRSA is a strain of bacterium that developed due to a mutation.

MRSA is difficult to treat so has led to high numbers of infections in hospital patients.

Explain why.

A

(MRSA is) resistant to / not killed by antibiotics

(as is a) new / different strain / type of bacterium

(therefore) people are not immune to it

(many) patients more susceptible to infection / weaker immune system

36
Q

Explain what a double blind trial is and why a double blind trial is good practice.

A

placebo and drug tested

allow fake drugs / sugar pills

1

neither patients nor doctors know (who has taken placebo or drug)

this full statement would gain 2 marks

1

(so) avoids bias

or

(therefore) controls for psychological effects

or

(so) can tell if drug works rather than placebo effect

37
Q

This is the method used.

1.   Mix yeast with sugar solution in a flask.

2.   Pour a layer of oil over the surface of the mixture.

3.   Put the flask in a water bath at 2 °C and leave for 20 minutes.

4.   Attach a gas syringe.

5.   Record the volume of gas collected every 5 minutes for 30 minutes.

6.   After 30 minutes move the flask to a water bath at 35 °C.

7.   Continue to record the volume of gas collected every 5 minutes.

(b)  Suggest why a layer of oil was needed on the surface of the mixture.

A

(b)  to keep oxygen out

38
Q

(c)  Suggest why the mixture was left for 20 minutes before the gas syringe was attached.

A

(c)  to allow the mixture / yeast / cells to reach the constant temperature

39
Q

Explain the results from 0 minutes to 45 minutes for the flask that was at 2 °C and was then moved to 35 °C.

Use Table 1 and Table 2.

A

allow (at 2 °C) few / no collisions (between sugar and enzymes)

1

(so) no carbon dioxide / gas produced

or

(so) fermentation did not occur

or

fermentation was very slow

do not accept an incorrect gas

1

enzymes become active at 35 °C so carbon dioxide / gas was produced

40
Q

(e)  Explain the results from 0 minutes to 45 minutes for the flask kept at 35 °C.

A

ideal / suitable temperature for enzymes / yeast to work

1

(so) carbon dioxide / gas produced (rapidly)

do not accept an incorrect gas

1

(after time / ≥ 15 minutes) rate / fermentation slowed

1

(because) sugar / glucose / food began to run out

or

(because) increased concentration of ethanol / alcohol started to kill the cells

41
Q

(a) Give one disease related to being overweight.

A

(Type 2) diabetes

ignore obesity

do not accept Type 1 diabetes allow cardiovascular disease ignore heart attack / failure

*   (coronary / ischaemic) heart disease / CHD

*   high blood pressure

*   cancer

*   depression

Practice questions (9 decks)

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